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Sample records for composition distribution life

  1. Assuring Life in Composite Systems

    NASA Technical Reports Server (NTRS)

    Chamis, Christos c.

    2008-01-01

    A computational simulation method is presented to assure life in composite systems by using dynamic buckling of smart composite shells as an example. The combined use of composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right below the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 9% at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load. The uncertainties in the electric field strength and smart material volume fraction have moderate effects and thereby in the assured life of the shell.

  2. SPECIES COMPOSITION, DISTRIBUTION, LIFE FORMS AND FOLK NOMENCLATURE OF FOREST AND COMMON LAND PLANTS OF WESTERN CHITWAN, NEPAL

    PubMed Central

    Dangol, D. R.

    2012-01-01

    This paper enumerates 349 plant species belonging to 77 families of vascular plants collected in the winter seasons of 1996 and 2000 by the flora teams of the Population and Ecology Research Laboratory, Nepal. Of the total species, 249 species belong to dicotyledons, 87 species to monocotyledons and 13 species to pteridophytes. Among the families, dicotyledons contributed the highest number of families (55 in number) followed by monocotyledons and pteridophytes. In the study areas, species composition varies with the type of habitats in the study plots. Some species are unique in distribution. The highest unique species are contributed by common lands (87 spp.), followed by the Chitwan National Park forest (36 spp.) and Tikauli forest (32 spp.). Ageratum houstonianum Mill., Cynodon dactylon (L.) Pers., Imperata cylindrica (L.) Beauv., Rungia parviflora (Retz.) Nees, Saccharum spontaneum L. and Thelypteris auriculata (J. Sm.) K. Iwats are the most common species across all the research blocks. Of the listed plants, many plants have local names either in Nepalese or other tribal languages. Plants are named in different ways on the basis of habit, habitat, smell, taste, and morphological characters of the plants, which are also the basis of nomenclature in plant taxonomy. PMID:22962539

  3. Effect of Individual Component Life Distribution on Engine Life Prediction

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.; Hendricks, Robert C.; Soditus, Sherry M.

    2003-01-01

    The effect of individual engine component life distributions on engine life prediction was determined. A Weibull-based life and reliability analysis of the NASA Energy Efficient Engine was conducted. The engine s life at a 95 and 99.9 percent probability of survival was determined based upon the engine manufacturer s original life calculations and assumed values of each of the component s cumulative life distributions as represented by a Weibull slope. The lives of the high-pressure turbine (HPT) disks and blades were also evaluated individually and as a system in a similar manner. Knowing the statistical cumulative distribution of each engine component with reasonable engineering certainty is a condition precedent to predicting the life and reliability of an entire engine. The life of a system at a given reliability will be less than the lowest-lived component in the system at the same reliability (probability of survival). Where Weibull slopes of all the engine components are equal, the Weibull slope had a minimal effect on engine L(sub 0.1) life prediction. However, at a probability of survival of 95 percent (L(sub 5) life), life decreased with increasing Weibull slope.

  4. The compositional distribution of asteroids

    NASA Astrophysics Data System (ADS)

    DeMeo, F.; Carry, B.; Alexander, C.; Walsh, K.; Chapman, C.

    2014-07-01

    Each compositional class of asteroid is a relic of the temperature and composition conditions in which it formed. The current distribution reveals the history of the Solar System, and each body acts as a marker of any mixing that occurred since formation. The remnant of a primordial temperature gradient, seen as transition from the S class to C class dominating in different regions of the asteroid belt has been a paradigm for three decades [1-4]. Today, we are armed with major advancements from the past decade that have revolutionized the field of asteroids in areas such as discovery, physical characterization, and dynamical models. A new and more detailed compositional map [5,6] created with data from the Sloan Digital Sky Survey [7] allows us to re-examine compositional trends in the main asteroid belt and what the physical and dynamical implications might be. This talk is related to recent work from DeMeo & Carry 2013, 2014 [5,6] and an upcoming chapter of the "Asteroids IV" book in 2015.

  5. Multiscale Fatigue Life Prediction for Composite Panels

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Yarrington, Phillip W.; Arnold, Steven M.

    2012-01-01

    Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer s coupling with NASA s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated. In this way, the effect of stress redistribution due to damage-induced stiffness change is captured, but the fatigue simulations remain computationally efficient. The model is compared to experimental fatigue life data for two composite facesheet/foam core sandwich panels, demonstrating very good agreement.

  6. A distributed program composition system

    NASA Technical Reports Server (NTRS)

    Brown, Robert L.

    1989-01-01

    A graphical technique for creating distributed computer programs is investigated and a prototype implementation is described which serves as a testbed for the concepts. The type of programs under examination is restricted to those comprising relatively heavyweight parts that intercommunicate by passing messages of typed objects. Such programs are often presented visually as a directed graph with computer program parts as the nodes and communication channels as the edges. This class of programs, called parts-based programs, is not well supported by existing computer systems; much manual work is required to describe the program to the system, establish the communication paths, accommodate the heterogeneity of data types, and to locate the parts of the program on the various systems involved. The work described solves most of these problems by providing an interface for describing parts-based programs in this class in a way that closely models the way programmers think about them: using sketches of diagraphs. Program parts, the computational modes of the larger program system are categorized in libraries and are accessed with browsers. The process of programming has the programmer draw the program graph interactively. Heterogeneity is automatically accommodated by the insertion of type translators where necessary between the parts. Many decisions are necessary in the creation of a comprehensive tool for interactive creation of programs in this class. Possibilities are explored and the issues behind such decisions are presented. An approach to program composition is described, not a carefully implemented programming environment. However, a prototype implementation is described that can demonstrate the ideas presented.

  7. Composites of porous metal and solid lubricants increase bearing life

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1967-01-01

    Self-lubricating composites of porous nickel and nickel-chromium alloy impregnated with a barium fluoride-calcium fluoride eutectic, and a thin film of solid lubricant increase wear life of load bearing surfaces.

  8. Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin; Minguet, Pierre J.

    2001-01-01

    A methodology is presented for determining the fatigue life of composite structures based on fatigue characterization data and geometric nonlinear finite element (FE) analyses. To demonstrate the approach, predicted results were compared to fatigue tests performed on specimens which represented a tapered composite flange bonded onto a composite skin. In a first step, tension tests were performed to evaluate the debonding mechanisms between the flange and the skin. In a second step, a 2D FE model was developed to analyze the tests. To predict matrix cracking onset, the relationship between the tension load and the maximum principal stresses transverse to the fiber direction was determined through FE analysis. Transverse tension fatigue life data were used to -enerate an onset fatigue life P-N curve for matrix cracking. The resulting prediction was in good agreement with data from the fatigue tests. In a third step, a fracture mechanics approach based on FE analysis was used to determine the relationship between the tension load and the critical energy release rate. Mixed mode energy release rate fatigue life data were used to create a fatigue life onset G-N curve for delamination. The resulting prediction was in good agreement with data from the fatigue tests. Further, the prediction curve for cumulative life to failure was generated from the previous onset fatigue life curves. The results showed that the methodology offers a significant potential to Predict cumulative fatigue life of composite structures.

  9. Considerations concerning fatigue life of metal matrix composites

    SciTech Connect

    Radhakrishnan, V.M.; Bartolotta, P.A.

    1993-05-01

    Since metal matrix composites (MMC) are composed from two very distinct materials each having their own physical and mechanical properties, it is feasible that the fatigue resistance depends on the strength of the weaker constituent. Based on this assumption, isothermal fatigue lives of several MMC's were analyzed utilizing a fatigue life diagram approach. For each MMC, the fatigue life diagram was quantified using the mechanical properties of its constituents. The fatigue life regions controlled by fiber fracture and matrix were also quantitatively defined.

  10. Considerations concerning fatigue life of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Radhakrishnan, V. M.; Bartolotta, Paul A.

    1993-01-01

    Since metal matrix composites (MMC) are composed from two very distinct materials each having their own physical and mechanical properties, it is feasible that the fatigue resistance depends on the strength of the weaker constituent. Based on this assumption, isothermal fatigue lives of several MMC's were analyzed utilizing a fatigue life diagram approach. For each MMC, the fatigue life diagram was quantified using the mechanical properties of its constituents. The fatigue life regions controlled by fiber fracture and matrix were also quantitatively defined.

  11. Tension fatigue analysis and life prediction for composite laminates

    NASA Technical Reports Server (NTRS)

    O'Brien, T. K.; Rigamonti, M.; Zanotti, C.

    1989-01-01

    A methodology is presented for the tension fatigue analysis and life prediction of composite laminates subjected to tension fatigue loading. The methodology incorporates both the generic fracture mechanics characterization of delamination and the assessment of the infuence of damage on laminate fatigue life. Tension fatigue tests were conducted on quasi-isotropic and orthotropic glass epoxy, graphite epoxy, and glass/graphite epoxy hybrid laminates, demonstrating good agreement between measured and predicted lives.

  12. Generation of Finite Life Distributional Goodman Diagrams for Reliability Prediction

    NASA Technical Reports Server (NTRS)

    Kececioglu, D.; Guerrieri, W. N.

    1971-01-01

    The methodology of developing finite life distributional Goodman diagrams and surfaces is described for presenting allowable combinations of alternating stress and mean stress to the design engineer. The combined stress condition is that of an alternating bending stress and a constant shear stress. The finite life Goodman diagrams and surfaces are created from strength distributions developed at various ratios of alternating to mean stress at particular cycle life values. The conclusions indicate that the Von Mises-Hencky ellipse, for cycle life values above 1000 cycles, is an adequate model of the finite life Goodman diagram. In addition, suggestions are made which reduce the number of experimental data points required in a fatigue data acquisition program.

  13. Life prediction of short fiber composites

    NASA Astrophysics Data System (ADS)

    Zago, Alessandro

    A procedure is described for estimating the fatigue lives (i.e. the number of cycles to failure) of parts made of short fiber reinforced thermoplastic matrix composites. First, S-N curves were generated at stress ratios of R = 0 and R = -1 for short glass fiber reinforced Copolyamide coupons with 0° (30% or 50% fiber content by weight), 45° (50% fiber content) and 90° (30% or 50% fiber content) fiber orientations. Second, these S-N curves were compared to data reported in the literature for a wide range of short glass and short carbon fiber reinforced thermoplastics materials. On the basis of these comparison, all available data were "collapsed" on two S-N curves, one for R = 0 and one for R = -l. The fatigue lives of short fiber reinforced thermoplastics were modeled by a Generalized Miner's Rule. Tests were conducted measuring the fatigue lives of 150 by 10 by 2 mm short glass fiber reinforced Copolyamide coupons under different types of cyclic loads. The fatigue lives measured in these tests were compared to those provided by the Generalized Miner's Rule, and good agreements were found between the test and model results. The fatigue lives of two different parts (made of short glass fiber reinforced Copolyamide) were then investigated. The first one was a 150 by 10 by 4 mm coupon with a 2 mm hole at the center. The second one was an automotive gear shift link. The fiber orientations and the stresses inside these parts were calculated, respectively, by the commercial softwares C-Mold and by ABAQUS. The fatigue lives under different cyclic loads were measured; they were also calculated by the Generalized Miner's Rule together with the results of C-Mold and ABAQUS and the S-N data generated in this study. Comparisons between the measured and estimated (by the model) fatigue lives are in reasonable agreement, indicating that the procedure employed is a useful tool for estimating the fatigue lives of parts made of short fiber reinforced thermoplastics.

  14. Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin

    2000-01-01

    A methodology is presented for determining the fatigue life of bonded composite skin/stringer structures based on delamination fatigue characterization data and geometric nonlinear finite element analyses. Results were compared to fatigue tests on stringer flange/skin specimens to verify the approach.

  15. Durability/life of fiber composites in hygrothermomechanical environments

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  16. Maximum likelihood estimation for life distributions with competing failure modes

    NASA Technical Reports Server (NTRS)

    Sidik, S. M.

    1979-01-01

    Systems which are placed on test at time zero, function for a period and die at some random time were studied. Failure may be due to one of several causes or modes. The parameters of the life distribution may depend upon the levels of various stress variables the item is subject to. Maximum likelihood estimation methods are discussed. Specific methods are reported for the smallest extreme-value distributions of life. Monte-Carlo results indicate the methods to be promising. Under appropriate conditions, the location parameters are nearly unbiased, the scale parameter is slight biased, and the asymptotic covariances are rapidly approached.

  17. Ceramic Matrix Composites (CMC) Life Prediction Development - 2003

    NASA Technical Reports Server (NTRS)

    Levine, Stanley R.; Calomino, Anthony M.; Verrilli, Michael J.; Thomas, David J.; Halbig, Michael C.; Opila, Elizabeth J.; Ellis, John R.

    2003-01-01

    Accurate life prediction is critical to successful use of ceramic matrix composites (CMCs). The tools to accomplish this are immature and not oriented toward the behavior of carbon fiber reinforced silicon carbide (C/SiC), the primary system of interest for many reusable and single mission launch vehicle propulsion and airframe applications. This paper describes an approach and progress made to satisfy the need to develop an integrated life prediction system that addresses mechanical durability and environmental degradation of C/SiC.

  18. A life prediction model for laminated composite structural components

    NASA Technical Reports Server (NTRS)

    Allen, David H.

    1990-01-01

    A life prediction methodology for laminated continuous fiber composites subjected to fatigue loading conditions was developed. A summary is presented of research completed. A phenomenological damage evolution law was formulated for matrix cracking which is independent of stacking sequence. Mechanistic and physical support was developed for the phenomenological evolution law proposed above. The damage evolution law proposed above was implemented to a finite element computer program. And preliminary predictions were obtained for a structural component undergoing fatigue loading induced damage.

  19. Dramatic increase in fatigue life in hierarchical graphene composites.

    PubMed

    Yavari, F; Rafiee, M A; Rafiee, J; Yu, Z-Z; Koratkar, N

    2010-10-01

    We report the synthesis and fatigue characterization of fiberglass/epoxy composites with various weight fractions of graphene platelets infiltrated into the epoxy resin as well as directly spray-coated on to the glass microfibers. Remarkably only ∼0.2% (with respect to the epoxy resin weight and ∼0.02% with respect to the entire laminate weight) of graphene additives enhanced the fatigue life of the composite in the flexural bending mode by up to 1200-fold. By contrast, under uniaxial tensile fatigue conditions, the graphene fillers resulted in ∼3-5-fold increase in fatigue life. The fatigue life increase (in the flexural bending mode) with graphene additives was ∼1-2 orders of magnitude superior to those obtained using carbon nanotubes. In situ ultrasound analysis of the nanocomposite during the cyclic fatigue test suggests that the graphene network toughens the fiberglass/epoxy-matrix interface and prevents the delamination/buckling of the glass microfibers under compressive stress. Such fatigue-resistant hierarchical materials show potential to improve the safety, reliability, and cost effectiveness of fiber-reinforced composites that are increasingly the material of choice in the aerospace, automotive, marine, sports, biomedical, and wind energy industries. PMID:20863061

  20. Bayesian estimation of life parameters in the Weibull distribution.

    NASA Technical Reports Server (NTRS)

    Canavos, G. C.; Tsokos, C. P.

    1973-01-01

    Development of a Bayesian analysis of the scale and shape parameters in the Weibull distribution and the corresponding reliability function with respect to the usual life-testing procedures. For the scale parameter theta, Bayesian estimates of theta and reliability are obtained for the uniform, exponential, and inverted gamma prior probability densities. Bhattacharya's results (1967) for the one-parameter exponential life-testing distribution are reduced to a special case of these results. A fully Bayesian analysis of both the scale and shape parameters is developed by assuming independent prior distributions; since in the latter case, analytical tractability is not possible, Bayesian estimates are obtained through a conjunction of Monte Carlo simulation and numerical-integration techniques. In both cases, a computer simulation is carried out, and a comparison is made between the Bayesian and the corresponding minimum-variance unbiased, or maximum likelihood, estimates. As expected, the Bayesian estimates are superior.

  1. Progressive Failure And Life Prediction of Ceramic and Textile Composites

    NASA Technical Reports Server (NTRS)

    Xue, David Y.; Shi, Yucheng; Katikala, Madhu; Johnston, William M., Jr.; Card, Michael F.

    1998-01-01

    An engineering approach to predict the fatigue life and progressive failure of multilayered composite and textile laminates is presented. Analytical models which account for matrix cracking, statistical fiber failures and nonlinear stress-strain behavior have been developed for both composites and textiles. The analysis method is based on a combined micromechanics, fracture mechanics and failure statistics analysis. Experimentally derived empirical coefficients are used to account for the interface of fiber and matrix, fiber strength, and fiber-matrix stiffness reductions. Similar approaches were applied to textiles using Repeating Unit Cells. In composite fatigue analysis, Walker's equation is applied for matrix fatigue cracking and Heywood's formulation is used for fiber strength fatigue degradation. The analysis has been compared with experiment with good agreement. Comparisons were made with Graphite-Epoxy, C/SiC and Nicalon/CAS composite materials. For textile materials, comparisons were made with triaxial braided and plain weave materials under biaxial or uniaxial tension. Fatigue predictions were compared with test data obtained from plain weave C/SiC materials tested at AS&M. Computer codes were developed to perform the analysis. Composite Progressive Failure Analysis for Laminates is contained in the code CPFail. Micromechanics Analysis for Textile Composites is contained in the code MicroTex. Both codes were adapted to run as subroutines for the finite element code ABAQUS and CPFail-ABAQUS and MicroTex-ABAQUS. Graphic user interface (GUI) was developed to connect CPFail and MicroTex with ABAQUS.

  2. Development of a Composite Delamination Fatigue Life Prediction Methodology

    NASA Technical Reports Server (NTRS)

    OBrien, Thomas K.

    2009-01-01

    Delamination is one of the most significant and unique failure modes in composite structures. Because of a lack of understanding of the consequences of delamination and the inability to predict delamination onset and growth, many composite parts are unnecessarily rejected upon inspection, both immediately after manufacture and while in service. NASA Langley is leading the efforts in the U.S. to develop a fatigue life prediction methodology for composite delamination using fracture mechanics. Research being performed to this end will be reviewed. Emphasis will be placed on the development of test standards for delamination characterization, incorporation of approaches for modeling delamination in commercial finite element codes, and efforts to mature the technology for use in design handbooks and certification documents.

  3. Life Cycle Assessment of Carbon Fiber-Reinforced Polymer Composites

    SciTech Connect

    Das, Sujit

    2011-01-01

    Carbon fiber-reinforced polymer matrix composites is gaining momentum with the pressure to lightweight vehicles, however energy-intensity and cost remain some of the major barriers before this material could be used in large-scale automotive applications. A representative automotive part, i.e., a 30.8 kg steel floor pan having a 17% weight reduction potential with stringent cash performance requirements has been considered for the life cycle energy and emissions analysis based on the latest developments occurring in the precursor type (conventional textile-based PAN vs. renewable-based lignin), part manufacturing (conventional SMC vs. P4) and fiber recycling technologies. Carbon fiber production is estimated to be about 14 times more energy-intensive than conventional steel production, however life cycle primary energy use is estimated to be quite similar to the conventional part, i.e., 18,500 MJ/part, especially when considering the uncertainty in LCI data that exists from using numerous sources in the literature. Lignin P4 technology offers the most life cycle energy and CO2 emissions benefits compared to a conventional stamped steel technology. With a 20% reduction in energy use in the lignin conversion to carbon fiber and free availability of lignin as a by-product of ethanol and wood production, a 30% reduction in life cycle energy use could be obtained. A similar level of life cycle energy savings could also be obtained with a higher part weight reduction potential of 43%.

  4. A self-healing polymer composite for extended fatigue life

    SciTech Connect

    Brown, E. N.; Jones, A. S.; White, S. R.; Sottos, Nancy R.

    2004-01-01

    A novel approach is explored for improving the fatigue life of thermosetting polymers through the addition of self-healing functionality. Thermosetting polymers are used in a wide variety of applications, but are susceptible to the initiation and propagation of small cracks deep within the structure where detection is difficult and repair is virtually impossible. The material under investigation is an epoxy matrix composite, which utilizes embedded microcapsules to store a healing agent and an embedded catalyst. A propagating crack exposes particles of catalyst and ruptures the microcapsules, which release healing agent into the crack plane. Polymerization of the healing agent is triggered by contact with the catalyst. Fatigue crack retardation and arrest from self-healing functionality result from crack-tip shielding mechanisms, such as hydrodynamic pressure and artificial-crack closure. In situ healing is observed to significantly extended fatigue life or permanently arrested fatigue crack growth over a wide range of loading conditions.

  5. Life history, diversity and distribution: A study of Japanese pteridophytes

    USGS Publications Warehouse

    Guo, Q.; Kato, Masako; Ricklefs, R.E.

    2003-01-01

    Many studies address the relationships between diversity or distribution and attributes of the physical environment. However, how these relationships are connected to variation in life history is poorly understood. This is particularly true in the case of pteridophytes. Japanese ferns and their allies comprise one of the best-known pteridophyte floras in the world. We analyzed ca 600 species of Japanese pteridophytes for which there is detailed information on distribution, reproduction, and chromosome number. Species richness was greatest in groups with a single reproductive mode (sexual, followed by apogamous), but distribution was greatest in species groups with multiple reproductive modes: sexual plus either sterile (irregular in meiosis) or apogamous. Geographical ranges varied greatly among species with small chromosome numbers but were uniformly small among species having high chromosome numbers. Seasonally green (mostly summer green) species had significantly larger distribution ranges than evergreen species. Endemic species had higher proportions of apogamy and sterility than non-endemic species. Seasonally green species had significantly larger distributional ranges, and a smaller proportion of species with apogamous reproduction, than evergreen species. There was no clear relationship between distribution and spore size, either among endemic species, non-endemic species, or all species combined. There was no relationship between spore size and chromosome number when all species were combined. However, positive relationships were detected within three of the nine largest genera, suggesting potential phylogenetic effects. We concluded that habitat availability, rather than dispersability, may be the limiting factor for the distribution of pteridophytes in Japan.

  6. Isothermal life prediction of composite lamina using a damage mechanics approach

    NASA Technical Reports Server (NTRS)

    Abuelfoutouh, Nader M.; Verrilli, Michael J.; Halford, Gary R.

    1989-01-01

    A method for predicting isothermal plastic fatigue life of a composite lamina is presented in which both fibers and matrix are isotropic materials. In general, the fatigue resistances of the matrix, fibers, and interfacial material must be known in order to predict composite fatigue life. Composite fatigue life is predicted using only the matrix fatigue resistance due to inelasticity micromechanisms. The effect of the fiber orientation on loading direction is accounted for while predicting composite life. The application is currently limited to isothermal cases where the internal thermal stresses that might arise from thermal strain mismatch between fibers and matrix are negligible. The theory is formulated to predict the fatigue life of a composite lamina under either load or strain control. It is applied currently to predict the life of tungsten-copper composite lamina at 260 C under tension-tension load control. The calculated life of the lamina is in good agreement with available composite low cycle fatigue data.

  7. Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifing Philosophy

    NASA Technical Reports Server (NTRS)

    Thesken, John C.; Murthy, Pappu L. N.; Phoenix, Leigh

    2007-01-01

    The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle's Kevlar-49 fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed non-conservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic-plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23% lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

  8. Proposed framework for thermomechanical life modeling of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Lerch, Bradley A.; Saltsman, James F.

    1993-01-01

    The framework of a mechanics of materials model is proposed for thermomechanical fatigue (TMF) life prediction of unidirectional, continuous-fiber metal matrix composites (MMC's). Axially loaded MMC test samples are analyzed as structural components whose fatigue lives are governed by local stress-strain conditions resulting from combined interactions of the matrix, interfacial layer, and fiber constituents. The metallic matrix is identified as the vehicle for tracking fatigue crack initiation and propagation. The proposed framework has three major elements. First, TMF flow and failure characteristics of in situ matrix material are approximated from tests of unreinforced matrix material, and matrix TMF life prediction equations are numerically calibrated. The macrocrack initiation fatigue life of the matrix material is divided into microcrack initiation and microcrack propagation phases. Second, the influencing factors created by the presence of fibers and interfaces are analyzed, characterized, and documented in equation form. Some of the influences act on the microcrack initiation portion of the matrix fatigue life, others on the microcrack propagation life, while some affect both. Influencing factors include coefficient of thermal expansion mismatch strains, residual (mean) stresses, multiaxial stress states, off-axis fibers, internal stress concentrations, multiple initiation sites, nonuniform fiber spacing, fiber debonding, interfacial layers and cracking, fractured fibers, fiber deflections of crack fronts, fiber bridging of matrix cracks, and internal oxidation along internal interfaces. Equations exist for some, but not all, of the currently identified influencing factors. The third element is the inclusion of overriding influences such as maximum tensile strain limits of brittle fibers that could cause local fractures and ensuing catastrophic failure of surrounding matrix material. Some experimental data exist for assessing the plausibility of the proposed framework.

  9. Distribution of Articles in Written Composition among Malaysian ESL Learners

    ERIC Educational Resources Information Center

    Rahim, Mia Emily Abdul; Rahim, Emma Marini Abdul; Ning, Chia Han

    2013-01-01

    The study aimed to investigate the distribution patterns of the English grammar articles (a, an, and the) as well as the distributions of their colligation patterns in written compositions of English among Malaysian ESL learners. This paper reports the results of a corpus-based study on articles used by these learners. The method used in this…

  10. Landscape structure and diseases profile: associating land use type composition with disease distribution.

    PubMed

    Votsi, Nefta-Eleftheria P; Mazaris, Antonios D; Kallimanis, Athanasios S; Drakou, Evangelia G; Pantis, John D

    2014-04-01

    Human health and well-being presuppose environmental quality. Several studies have documented the indicative role of land use types in environmental quality. However, the exact role of land use composition on disease distribution has remained scientifically vague. We assessed the congruence of diseases' distribution with land use composition, focusing on high environmental quality areas, defined as tranquil areas with view to indicating places offering well-being. Landscape composition is linked to the presence of diseases across 51 prefectures of Greece. Agricultural and natural land use types proved to be the main drivers of disease distribution. Tranquility demonstrated a strong negative correlation with population density, thus could be considered as a quantitative spatial index of life-quality. We concluded that the landscape context affects the dominance of diseases' patterns. Special emphasis should be put on the role of tranquil areas in human health and the relative environmental health policies. PMID:23802561

  11. Life Modeling and Design Analysis for Ceramic Matrix Composite Materials

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The primary research efforts focused on characterizing and modeling static failure, environmental durability, and creep-rupture behavior of two classes of ceramic matrix composites (CMC), silicon carbide fibers in a silicon carbide matrix (SiC/SiC) and carbon fibers in a silicon carbide matrix (C/SiC). An engineering life prediction model (Probabilistic Residual Strength model) has been developed specifically for CMCs. The model uses residual strength as the damage metric for evaluating remaining life and is posed probabilistically in order to account for the stochastic nature of the material s response. In support of the modeling effort, extensive testing of C/SiC in partial pressures of oxygen has been performed. This includes creep testing, tensile testing, half life and residual tensile strength testing. C/SiC is proposed for airframe and propulsion applications in advanced reusable launch vehicles. Figures 1 and 2 illustrate the models predictive capabilities as well as the manner in which experimental tests are being selected in such a manner as to ensure sufficient data is available to aid in model validation.

  12. Ceramic Matrix Composites (CMC) Life Prediction Method Development

    NASA Technical Reports Server (NTRS)

    Levine, Stanley R.; Calomino, Anthony M.; Ellis, John R.; Halbig, Michael C.; Mital, Subodh K.; Murthy, Pappu L.; Opila, Elizabeth J.; Thomas, David J.; Thomas-Ogbuji, Linus U.; Verrilli, Michael J.

    2000-01-01

    Advanced launch systems (e.g., Reusable Launch Vehicle and other Shuttle Class concepts, Rocket-Based Combine Cycle, etc.), and interplanetary vehicles will very likely incorporate fiber reinforced ceramic matrix composites (CMC) in critical propulsion components. The use of CMC is highly desirable to save weight, to improve reuse capability, and to increase performance. CMC candidate applications are mission and cycle dependent and may include turbopump rotors, housings, combustors, nozzle injectors, exit cones or ramps, and throats. For reusable and single mission uses, accurate prediction of life is critical to mission success. The tools to accomplish life prediction are very immature and not oriented toward the behavior of carbon fiber reinforced silicon carbide (C/SiC), the primary system of interest for a variety of space propulsion applications. This paper describes an approach to satisfy the need to develop an integrated life prediction system for CMC that addresses mechanical durability due to cyclic and steady thermomechanical loads, and takes into account the impact of environmental degradation.

  13. Elucidating the Composition and Distribution of Trace Metals in Corals

    NASA Astrophysics Data System (ADS)

    Farfan, G.; Webb, S. M.; Apprill, A.; Hansel, C. M.

    2014-12-01

    Coral reefs host a plethora of marine life and thereby provide a wealth of aesthetic and economic benefits to coastal countries. Anthropogenic influences, including local coastal water contamination, however threaten the health of these delicate ecosystems. Metal incorporation into carbonate minerals, the backbone of coral reefs, is known to have a large yet variable impact on carbonate structure and solubility. Yet, trace metal influences on the structure, porosity, composition, and solubility of coral skeletons is largely unknown. Here, we coupled synchrotron-based micro-X-ray fluorescence (u-XRF) mapping and X-ray absorption near edge structure (XANES) spectroscopy with micro-X-ray diffraction (XRD) to explore the distribution and speciation of trace metals associated with corals and their impact on the carbonate structure of corals obtained from reefs varying in anthropogenic influence - Florida Keys, FL USA and the Federated States of Micronesia. Iron and copper were the most abundant metals in the biological tissue, while in some areas zinc was observed in the tissue, overlapping with the skeleton. Trace metals were not detectable in the aragonite skeletons; in fact, the distributions of Ca and Fe were anti-correlated. XANES spectra show that the iron is primarily Fe(III), likely as the poorly crystalline iron oxide ferrihydrite structure or trapped within ferretin proteins. The same trace metals were observed in corals of different species and from different environments. This in situ investigation corroborates previous studies that corals tend to incorporate iron into the biological components but not into the aragonite skeleton. Given the dominant partitioning of metals within the biological tissue rather than the coral skeleton, the specific carbon molecules responsible for metal attenuation and their fate under changing geochemical conditions and following coral death require exploration.

  14. An empirical Bayes approach for the Poisson life distribution.

    NASA Technical Reports Server (NTRS)

    Canavos, G. C.

    1973-01-01

    A smooth empirical Bayes estimator is derived for the intensity parameter (hazard rate) in the Poisson distribution as used in life testing. The reliability function is also estimated either by using the empirical Bayes estimate of the parameter, or by obtaining the expectation of the reliability function. The behavior of the empirical Bayes procedure is studied through Monte Carlo simulation in which estimates of mean-squared errors of the empirical Bayes estimators are compared with those of conventional estimators such as minimum variance unbiased or maximum likelihood. Results indicate a significant reduction in mean-squared error of the empirical Bayes estimators over the conventional variety.

  15. The composition of the gut microbiota throughout life, with an emphasis on early life

    PubMed Central

    Rodríguez, Juan Miguel; Murphy, Kiera; Stanton, Catherine; Ross, R. Paul; Kober, Olivia I.; Juge, Nathalie; Avershina, Ekaterina; Rudi, Knut; Narbad, Arjan; Jenmalm, Maria C.; Marchesi, Julian R.; Collado, Maria Carmen

    2015-01-01

    The intestinal microbiota has become a relevant aspect of human health. Microbial colonization runs in parallel with immune system maturation and plays a role in intestinal physiology and regulation. Increasing evidence on early microbial contact suggest that human intestinal microbiota is seeded before birth. Maternal microbiota forms the first microbial inoculum, and from birth, the microbial diversity increases and converges toward an adult-like microbiota by the end of the first 3–5 years of life. Perinatal factors such as mode of delivery, diet, genetics, and intestinal mucin glycosylation all contribute to influence microbial colonization. Once established, the composition of the gut microbiota is relatively stable throughout adult life, but can be altered as a result of bacterial infections, antibiotic treatment, lifestyle, surgical, and a long-term change in diet. Shifts in this complex microbial system have been reported to increase the risk of disease. Therefore, an adequate establishment of microbiota and its maintenance throughout life would reduce the risk of disease in early and late life. This review discusses recent studies on the early colonization and factors influencing this process which impact on health. PMID:25651996

  16. NPU-based image compositing in a distributed visualization system.

    PubMed

    Pugmire, David; Monroe, Laura; Connor Davenport, Carolyn; DuBois, Andrew; DuBois, David; Poole, Stephen

    2007-01-01

    This paper describes the first use of a Network Processing Unit (NPU) to perform hardware-based image composition in a distributed rendering system. The image composition step is a notorious bottleneck in a clustered rendering system. Furthermore, image compositing algorithms do not necessarily scale as data size and number of nodes increase. Previous researchers have addressed the composition problem via software and/or custom-built hardware. We used the heterogeneous multicore computation architecture of the Intel IXP28XX NPU, a fully programmable commercial off-the-shelf (COTS) technology, to perform the image composition step. With this design, we have attained a nearly four-times performance increase over traditional software-based compositing methods, achieving sustained compositing rates of 22-28 fps on a 1,024 x 1,024 image. This system is fully scalable with a negligible penalty in frame rate, is entirely COTS, and is flexible with regard to operating system, rendering software, graphics cards, and node architecture. The NPU-based compositor has the additional advantage of being a modular compositing component that is eminently suitable for integration into existing distributed software visualization packages. PMID:17495338

  17. An overview of computational simulation methods for composite structures failure and life analysis

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1993-01-01

    Three parallel computational simulation methods are being developed at the LeRC Structural Mechanics Branch (SMB) for composite structures failure and life analysis: progressive fracture CODSTRAN; hierarchical methods for high-temperature composites; and probabilistic evaluation. Results to date demonstrate that these methods are effective in simulating composite structures failure/life/reliability.

  18. Fast adaptive composite grid methods on distributed parallel architectures

    NASA Technical Reports Server (NTRS)

    Lemke, Max; Quinlan, Daniel

    1992-01-01

    The fast adaptive composite (FAC) grid method is compared with the adaptive composite method (AFAC) under variety of conditions including vectorization and parallelization. Results are given for distributed memory multiprocessor architectures (SUPRENUM, Intel iPSC/2 and iPSC/860). It is shown that the good performance of AFAC and its superiority over FAC in a parallel environment is a property of the algorithm and not dependent on peculiarities of any machine.

  19. Barium distributions in teeth reveal early-life dietary transitions in primates.

    PubMed

    Austin, Christine; Smith, Tanya M; Bradman, Asa; Hinde, Katie; Joannes-Boyau, Renaud; Bishop, David; Hare, Dominic J; Doble, Philip; Eskenazi, Brenda; Arora, Manish

    2013-06-13

    Early-life dietary transitions reflect fundamental aspects of primate evolution and are important determinants of health in contemporary human populations. Weaning is critical to developmental and reproductive rates; early weaning can have detrimental health effects but enables shorter inter-birth intervals, which influences population growth. Uncovering early-life dietary history in fossils is hampered by the absence of prospectively validated biomarkers that are not modified during fossilization. Here we show that large dietary shifts in early life manifest as compositional variations in dental tissues. Teeth from human children and captive macaques, with prospectively recorded diet histories, demonstrate that barium (Ba) distributions accurately reflect dietary transitions from the introduction of mother's milk through the weaning process. We also document dietary transitions in a Middle Palaeolithic juvenile Neanderthal, which shows a pattern of exclusive breastfeeding for seven months, followed by seven months of supplementation. After this point, Ba levels in enamel returned to baseline prenatal levels, indicating an abrupt cessation of breastfeeding at 1.2 years of age. Integration of Ba spatial distributions and histological mapping of tooth formation enables novel studies of the evolution of human life history, dietary ontogeny in wild primates, and human health investigations through accurate reconstructions of breastfeeding history. PMID:23698370

  20. Life history traits to predict biogeographic species distributions in bivalves.

    PubMed

    Montalto, V; Rinaldi, A; Sarà, G

    2015-10-01

    Organismal fecundity (F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species (Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provided to test model performance in predicting the bivalve distribution throughout the 22 sites in the Central Mediterranean Sea under local conditions of food density and body temperature. Model skill and stationarity were tested through the estimate of commission (i.e., proportion of species' absences predicted present) and omission (i.e., proportion of presences predicted absent) errors of predictions by comparing mechanistic predicted vs. observed F and BS values throughout the study area extrapolated by lab experiments and literature search. The resulting relationship was reliable for both species, and body size and fecundity were highly correlated in M. galloprovincialis compared to B. pharaonis; FT-DEB showed correct predictions of presence in more than 75 % of sites, and the regression between BS predicted vs. observed was highly significant in both species. Whilst recognising the importance of biotic interactions in shaping the distribution of species, our FT-DEB approach provided reliable quantitative estimates of where our species had sufficient F to support local populations or suggesting reproductive failure. Mechanistically, estimating F and BS as key traits of species life history can also be addressed within a broader, scale-dependent context that surpasses the limitations related to correlative species distribution models. PMID:26373559

  1. Life history traits to predict biogeographic species distributions in bivalves

    NASA Astrophysics Data System (ADS)

    Montalto, V.; Rinaldi, A.; Sarà, G.

    2015-10-01

    Organismal fecundity ( F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species ( Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provided to test model performance in predicting the bivalve distribution throughout the 22 sites in the Central Mediterranean Sea under local conditions of food density and body temperature. Model skill and stationarity were tested through the estimate of commission (i.e., proportion of species' absences predicted present) and omission (i.e., proportion of presences predicted absent) errors of predictions by comparing mechanistic predicted vs. observed F and BS values throughout the study area extrapolated by lab experiments and literature search. The resulting relationship was reliable for both species, and body size and fecundity were highly correlated in M. galloprovincialis compared to B. pharaonis; FT-DEB showed correct predictions of presence in more than 75 % of sites, and the regression between BS predicted vs. observed was highly significant in both species. Whilst recognising the importance of biotic interactions in shaping the distribution of species, our FT-DEB approach provided reliable quantitative estimates of where our species had sufficient F to support local populations or suggesting reproductive failure. Mechanistically, estimating F and BS as key traits of species life history can also be addressed within a broader, scale-dependent context that surpasses the limitations related to correlative species distribution models.

  2. Composition distributions of particles in a gelling mixture

    NASA Astrophysics Data System (ADS)

    Lushnikov, A. A.

    2014-03-01

    Gelation in a two component disperse system wherein binary coagulation governs the temporal changes of particle composition spectra is studied for the crossproduct coagulation kernel proportional to m1n2+m2n1, with m ,n being the numbers of monomers of the first and the second component in the coalescing pair of particles. This model reveals the sol-gel transition, i.e., after a finite interval of time the conservation of the total particle mass concentration violates because of the formation of giant particles (the gel). This paper reports on the exact solution of this model for arbitrary initial particle composition spectra. Exact expressions for the particle composition spectrum, the gel mass, and the second moments of the composition distribution are derived. Two scenarios of gelation, where the gel is either active or passive, are considered.

  3. The distribution of all French communes: A composite parametric approach

    NASA Astrophysics Data System (ADS)

    Calderín-Ojeda, Enrique

    2016-05-01

    The distribution of the size of all French settlements (communes) from 1962 to 2012 is examined by means of a three-parameter composite Lognormal-Pareto distribution. This model is based on a Lognormal density up to an unknown threshold value and a Pareto density thereafter. Recent findings have shown that the untruncated settlement size data is in excellent agreement with the Lognormal distribution in the lower and central parts of the empirical distribution, but it follows a power law in the upper tail. For that reason, this probabilistic family, that nests both models, seems appropriate to describe urban agglomeration in France. The outcomes of this paper reveal that for the early periods (1962-1975) the upper quartile of the commune size data adheres closely to a power law distribution, whereas for later periods (2006-2012) most of the city size dynamics is explained by a Lognormal model.

  4. Fatigue Life Analysis of Tapered Hybrid Composite Flexbeams

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; Schaff, Jeffery R.; Dobyns, Alan L.

    2002-01-01

    Nonlinear-tapered flexbeam laminates from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. The two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) obtained from the above codes using the virtual crack closure technique (VCCT) at a resin crack location in the flexbeams are presented for both hybrid material types. These results compare well with each other and suggest that the initial delamination growth from the resin crack toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves and compared with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared reasonably well with the test results.

  5. Fatigue Life Methodology for Tapered Hybrid Composite Flexbeams

    NASA Technical Reports Server (NTRS)

    urri, Gretchen B.; Schaff, Jeffery R.

    2006-01-01

    Nonlinear-tapered flexbeam specimens from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. Two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) associated with simulated delamination growth in the flexbeams are presented from both codes. These results compare well with each other and suggest that the initial delamination growth from the tip of the ply-drop toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves for comparison with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared well with the test results.

  6. Tension fatigue analysis and life prediction for composite laminates

    NASA Technical Reports Server (NTRS)

    Obrien, T. K.; Rigamonti, M.; Zanotti, C.

    1988-01-01

    A tension fatigue life prediction methodology for composite laminates is presented. Tension fatigue tests were conducted on quasi-isotropic and orthotropic glass epoxy, graphite epoxy, and glass/graphite epoxy hybrid laminates. Edge delamination onset data were used to generate plots of strain energy release rate as a function of cycles to delamination onset. These plots were then used along with strain energy release rate analyses of delaminations initiating at matrix cracks to predict local delamination onset. Stiffness loss was measured experimentally to account for the accumulation of matrix cracks and for delamination growth. Fatigue failure was predicted by comparing the increase in global strain resulting from stiffness loss to the decrease in laminate failure strain resulting from delaminations forming at matrix cracks through the laminate thickness. Good agreement between measured and predicted lives indicated that the through-thickness damage accumulation model can accurately describe fatigue failure for laminates where the delamination onset behavior in fatigue is well characterized, and stiffness loss can be monitored in real time to account for damage growth.

  7. Life prediction for white OLED based on LSM under lognormal distribution

    NASA Astrophysics Data System (ADS)

    Zhang, Jianping; Liu, Fang; Liu, Yu; Wu, Helen; Zhu, Wenqing; Wu, Wenli; Wu, Liang

    2012-09-01

    In order to acquire the reliability information of White Organic Light Emitting Display (OLED), three groups of OLED constant stress accelerated life tests (CSALTs) were carried out to obtain failure data of samples. Lognormal distribution function was applied to describe OLED life distribution, and the accelerated life equation was determined by Least square method (LSM). The Kolmogorov-Smirnov test was performed to verify whether the white OLED life meets lognormal distribution or not. Author-developed software was employed to predict the average life and the median life. The numerical results indicate that the white OLED life submits to lognormal distribution, and that the accelerated life equation meets inverse power law completely. The estimated life information of the white OLED provides manufacturers and customers with important guidelines.

  8. 41 CFR 101-27.209 - Utilization and distribution of shelf-life items.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... distribution of shelf-life items. 101-27.209 Section 101-27.209 Public Contracts and Property Management... PROCUREMENT 27-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined that specified quantities of both Type I and Type...

  9. 41 CFR 101-27.209 - Utilization and distribution of shelf-life items.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... distribution of shelf-life items. 101-27.209 Section 101-27.209 Public Contracts and Property Management... PROCUREMENT 27-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined that specified quantities of both Type I and Type...

  10. 41 CFR 101-27.209 - Utilization and distribution of shelf-life items.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... distribution of shelf-life items. 101-27.209 Section 101-27.209 Public Contracts and Property Management... PROCUREMENT 27-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined that specified quantities of both Type I and Type...

  11. 41 CFR 101-27.209 - Utilization and distribution of shelf-life items.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... distribution of shelf-life items. 101-27.209 Section 101-27.209 Public Contracts and Property Management... PROCUREMENT 27-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined that specified quantities of both Type I and Type...

  12. 41 CFR 101-27.209 - Utilization and distribution of shelf-life items.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... distribution of shelf-life items. 101-27.209 Section 101-27.209 Public Contracts and Property Management... PROCUREMENT 27-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined that specified quantities of both Type I and Type...

  13. Spatial distribution of volatile compounds in graphite composites

    NASA Technical Reports Server (NTRS)

    Grayson, M. A.; Wolf, C. J.; Kourtides, D. A.

    1980-01-01

    The distribution of water and other volatile compounds such as acetone and phenol was measured as a function of depth in four graphite resin matrix composites. Precision abrasion mass spectrometry was used to qualitatively and quantitatively characterize the indigenous volatile compounds in the as received condition and after drying in an environmentally controlled oven. The total amount of water in the composites varied from 0.12 wt% to 1.1 wt% and the times required to dry the samples ranged from less than 96 h to much greater than 555 h.

  14. Distributed photoacoustic system for cure monitoring of composites

    NASA Astrophysics Data System (ADS)

    Fomitchov, Pavel A.; Kim, Yeong K.; Kromine, Alexei K.; Krishnaswamy, Sridhar; Achenbach, Jan D.; Daniel, Isaac M.

    2001-07-01

    In this paper we describe a laser ultrasonic system for real-time monitoring of the degree of cure of a graphite-epoxy composite part during manufacturing. The system is integrated with a Resin-Transfer Molding (RTM) machine, and contains (i) a fiberized laser ultrasonic source, and (ii) an embedded ultrasonic sensor based on an intrinsic fiber optic Sagnac interferometer. Bulk ultrasonic waves generated by the laser source are transmitted into the composite structure and are subsequently detected by the embedded ultrasonic sensor. The degree of cure can be obtained from measurements of ultrasonic velocity and attenuation in the composite part. The use of an optical switch in the fiber optic delivery system of the laser ultrasonic source allows ultrasonic generation at several locations of the composite part. In this paper we discuss the design of the laser ultrasonic source and the sensor optimized for cure monitoring applications, and their integration with the RTM mold. The results of ultrasonic measurements during manufacturing of a composite specimen are presented. Our results show that laser ultrasonics offer distinct advantages for manufacturing of modern composite structures including the ability to operate in a high temperature and high pressure environment and provide distributed sensing that can cover critical areas of a component.

  15. Fatigue Life Methodology for Tapered Composite Flexbeam Laminates

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; O''Brien, T. Kevin; Rousseau, Carl Q.

    1997-01-01

    The viability of a method for determining the fatigue life of composite rotor hub flexbeam laminates using delamination fatigue characterization data and a geometric non-linear finite element (FE) analysis was studied. Combined tension and bending loading was applied to nonlinear tapered flexbeam laminates with internal ply drops. These laminates, consisting of coupon specimens cut from a full-size S2/E7T1 glass-epoxy flexbeam were tested in a hydraulic load frame under combined axial-tension and transverse cyclic bending loads. The magnitude of the axial load remained constant and the direction of the load rotated with the specimen as the cyclic bending load was applied. The first delamination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group. Subsequently, unstable delamination occurred by complete delamination along the length of the specimen. Continued cycling resulted in multiple delaminations. A 2D finite element model of the flexbeam was developed and a geometrically non-linear analysis was performed. The global responses of the model and test specimens agreed very well in terms of the transverse flexbeam tip-displacement and flapping angle. The FE model was used to calculate strain energy release rates (G) for delaminations initiating at the tip of the outer ply-drop area and growing toward the thick or thin regions of the flexbeam, as was observed in the specimens. The delamination growth toward the thick region was primarily mode 2, whereas delamination growth toward the thin region was almost completely mode 1. Material characterization data from cyclic double-cantilevered beam tests was used with the peak calculated G values to generate a curve predicting fatigue failure by unstable delamination as a function of the number of loading cycles. The calculated fatigue lives compared well with the test data.

  16. Fatigue Life Methodology for Tapered Composite Flexbeam Laminates

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; OBrien, T. Kevin; Rousseau, Carl Q.

    1997-01-01

    The viability of a method for determining the fatigue life of composite rotor hub flexbeam laminates using delamination fatigue characterization data and a geometric non-linear finite element (FE) analysis was studied. Combined tension and bending loading was applied to non-linear tapered flexbeam laminates with internal ply drops. These laminates, consisting of coupon specimens cut from a full-size S2/E7T1 glass-epoxy flexbeam were tested in a hydraulic load frame under combined axial-tension and transverse cyclic bending. The magnitude of the axial load remained constant and the direction of the load rotated with the specimen as the cyclic bending load was applied. The first delamination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group. Subsequently, unstable delamination occurred by complete delamination along the length of the specimen. Continued cycling resulted in multiple delaminations. A 2D finite element model of the flexbeam was developed and a geometrically non-linear analysis was performed. The global responses of the model and test specimens agreed very well in terms of the transverse displacement. The FE model was used to calculate strain energy release rates (G) for delaminations initiating at the tip of the outer ply-drop area and growing toward the thick or thin regions of the flexbeam, as was observed in the specimens. The delamination growth toward the thick region was primarily mode 2, whereas delamination growth toward the thin region was almost completely mode 1. Material characterization data from cyclic double-cantilevered beam tests was used with the peak calculated G values to generate a curve predicting fatigue failure by unstable delamination as a function of the number of loading cycles. The calculated fatigue lives compared well with the test data.

  17. Quantum key distribution on composite photons, polarization qutrits

    NASA Astrophysics Data System (ADS)

    Kulik, S. P.; Molotkov, S. N.; Radchenko, I. V.

    2012-11-01

    Polarization states of a photon are the most natural degrees of freedom for encoding classical information bits. The two-dimensional space of states associated with polarization degrees of freedom of the photon is insufficient for many problems of information transfer with quantum states. We propose to use the polarization degrees of freedom of composite states of photons (polarization qutrits) for secret cryptographic key distribution.

  18. Stress Rupture Life Reliability Measures for Composite Overwrapped Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Thesken, John C.; Phoenix, S. Leigh; Grimes-Ledesma, Lorie

    2007-01-01

    Composite Overwrapped Pressure Vessels (COPVs) are often used for storing pressurant gases onboard spacecraft. Kevlar (DuPont), glass, carbon and other more recent fibers have all been used as overwraps. Due to the fact that overwraps are subjected to sustained loads for an extended period during a mission, stress rupture failure is a major concern. It is therefore important to ascertain the reliability of these vessels by analysis, since the testing of each flight design cannot be completed on a practical time scale. The present paper examines specifically a Weibull statistics based stress rupture model and considers the various uncertainties associated with the model parameters. The paper also examines several reliability estimate measures that would be of use for the purpose of recertification and for qualifying flight worthiness of these vessels. Specifically, deterministic values for a point estimate, mean estimate and 90/95 percent confidence estimates of the reliability are all examined for a typical flight quality vessel under constant stress. The mean and the 90/95 percent confidence estimates are computed using Monte-Carlo simulation techniques by assuming distribution statistics of model parameters based also on simulation and on the available data, especially the sample sizes represented in the data. The data for the stress rupture model are obtained from the Lawrence Livermore National Laboratories (LLNL) stress rupture testing program, carried out for the past 35 years. Deterministic as well as probabilistic sensitivities are examined.

  19. Distribution of early life history stages of fishes in selected pools of the upper Mississippi River

    USGS Publications Warehouse

    Holland, L.E.

    1986-01-01

    Effective management of the fishery resources of the Upper Mississippi River and successful mitigation of the loss of critical habitat depend in part on an understanding of the reproductive and early life history requirements of the affected fishes. However, little is known about the use of nursery areas by fishes in the river. Of the nearly 130 species identified in the adult ichthyofauna, only a few are represented proportionally in the available data on early life stages because study designs have not included consideration of the early stages, collection gears have not adequately sampled the young, and eggs and larvae of some species are difficult to sample by conventional approaches. For the species collected, information is available on seasonal variations in total densities, composition, and catch among different habitat types. However, the data are most accurate for species with buoyant early life stages, such as freshwater drum (Aplodinotus grunniens) and gizzard shad (Dorosoma cepedianum). Eggs and larvae of freshwater drum dominate collections made in the main channel, whereas other larval fishes are usually most abundant in backwater habitats. The species found there usually deposit eggs on the substrate or on vegetation. Habitat preferences (as indicated by relative abundance) often shift as development proceeds and physical and behavioral changes occur in the larvae. Only limited information is available on the distribution of larvae within habitats, but it is clear that variations within habitats are significant.

  20. The Schiff angular bremsstrahlung distribution from composite media

    NASA Astrophysics Data System (ADS)

    Taylor, M. L.; Dalton, B.; Franich, R. D.

    2012-12-01

    The Schiff differential for the angular distribution of bremsstrahlung is widely employed, but calculations involving composite materials (i.e. compounds and mixtures) are often undertaken in a somewhat ad hoc fashion. In this work, we suggest an alternative approach to power-law estimates of the effective atomic number utilising Seltzer and Berger's combined approach in order to generate single-valued effective atomic numbers applicable over a large energy range (in the worst case deviation from constancy of about 2% between 10 keV and 1 GeV). Differences with power-law estimates of Z for composites are potentially significant, particularly for low-Z media such as biological or surrogate materials as relevant within the context of medical physics. As an example, soft tissue differs by >70% and cortical bone differs by >85%, while for high-Z composites such as a tungsten-rhenium alloy the difference is of the order of 1%. Use of the normalised Schiff formula for shape only does not exhibit strong Z dependence. Consequently, in such contexts the differences are negligible - the power-law approach overestimates the magnitude by 1.05% in the case of water and underestimates it by <0.1% for the high-Z alloys. The differences in the distribution are most pronounced for small angles and where the bremsstrahlung quanta are low energy.

  1. Nondestructive Characterization Techniques Used for Ceramic Matrix Composite Life Determination

    NASA Technical Reports Server (NTRS)

    Effinger, Michael; Koenig, John; Ellingson, Bill; Spohnholtz, Todd

    2000-01-01

    Recent results indicate that the specific damping capacity and resonant frequency measurements taken periodically during a component's lifetime is able to quantify the mechanical fatigue of CMCS. This gives hope for the potential of determining the actual and residual life of CMC materials using a combination of nondestructive techniques. If successful, then this new paradigm for life prediction of CMCs could revolutionize the approach for designing and servicing CMC components, thereby significantly reducing costs for design, development, health monitoring, and maintenance of CMC components and systems. The Nondestructive Characterization (NDC) life prediction approach would complement life prediction using micromechanics and continuum finite element models. This paper reports on the initial concept of NDC life prediction, a review of the C/SiC blisk damping data, and how changes in the specific damping capacity & ultrasonic elastic modulus data have established the concept as a possibility.

  2. A Component-based Programming Model for Composite, Distributed Applications

    NASA Technical Reports Server (NTRS)

    Eidson, Thomas M.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    The nature of scientific programming is evolving to larger, composite applications that are composed of smaller element applications. These composite applications are more frequently being targeted for distributed, heterogeneous networks of computers. They are most likely programmed by a group of developers. Software component technology and computational frameworks are being proposed and developed to meet the programming requirements of these new applications. Historically, programming systems have had a hard time being accepted by the scientific programming community. In this paper, a programming model is outlined that attempts to organize the software component concepts and fundamental programming entities into programming abstractions that will be better understood by the application developers. The programming model is designed to support computational frameworks that manage many of the tedious programming details, but also that allow sufficient programmer control to design an accurate, high-performance application.

  3. Wear and Life Characteristics of Microwave-Sintered Copper-Graphite Composite

    NASA Astrophysics Data System (ADS)

    Rajkumar, K.; Aravindan, S.; Kulkarni, M. S.

    2012-11-01

    Copper-graphite composite is an important tribological material used in electrical sliding contact applications like electrical brushes in motors and generators. The electrical sliding contact experiences multiple stresses such as mechanical pressure and temperature. Traditional life tests under normal operating condition would be a time-consuming process due to the longer expected life of the composite. Accelerated wear testing was carried out to evaluate the life characteristics of the composite. This work focuses on evaluation of tribological performance of microwave-sintered copper-graphite composite using accelerated wear testing methodology using high temperature pin-on-disc tribometer. Microstructural studies of worn out surfaces were carried out using SEM with EDAX. Reliability and analysis on life characteristics were performed on the time-to-failure data using temperature-nonthermal-accelerated life-stress model. The obtained times-to-failure data from the accelerated wear testing was extrapolated to normal usage condition. Temperature and pressure are significantly affecting the wear performance. Self-lubricating action of graphite and improvement in wear resistance is helpful in extending the life of copper graphite composite. The life of the composite obtained through testing at mean and 99% reliability are 18,725 and 16,950 h, respectively.

  4. Influence of Material Distribution on Impact Resistance of Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Abatan, Ayu; Hu, Hurang

    1998-01-01

    Impact events occur in a wide variety of circumstances. A typical example is a bullet impacting a target made of composite material. These impact events produce time-varying loads on a structure that can result in damage. As a first step to understanding the damage resistance issue in composite laminates, an accurate prediction of the transient response during an impact event is necessary. The analysis of dynamic loadings on laminated composite plates has undergone considerable development recently. Rayleigh-Ritz energy method was used to determine the impact response of laminated plates. The impact response of composite plates using shear deformation plate theory was analyzed. In recent work a closed-form solution was obtained for a rectangular plate with four edges simply supported subjected to a center impact load using classical plate theory. The problem was further investigated and the analysis results compared of both classical plate theory and shear deformation theory, and found that classical plate theory predicts very accurate results for the range of small deformations considered. In this study, the influence of cross sectional material distribution on the comparative impact responses of hybrid metal laminates subjected to low and medium velocity impacts is investigated. A simple linear model to evaluate the magnitude of the impact load is proposed first, and it establishes a relation between the impact velocity and the impact force. Then a closed-form solution for impact problem is presented. The results were compared with the finite element analysis results. For an 11 layer-hybrid laminate, the impact response as a function of material distribution in cross-section is presented. With equal areal weight, the effect of the number of laminate layers on the impact resistance is also investigated. Finally, the significance of the presented results is discussed.

  5. Stressed Oxidation Life Prediction for C/SiC Composites

    NASA Technical Reports Server (NTRS)

    Levine, Stanley R.

    2004-01-01

    The residual strength and life of C/SiC is dominated by carbon interface and fiber oxidation if seal coat and matrix cracks are open to allow oxygen ingress. Crack opening is determined by the combination of thermal, mechanical and thermal expansion mismatch induced stresses. When cracks are open, life can be predicted by simple oxidation based models with reaction controlled kinetics at low temperature, and by gas phase diffusion controlled kinetics at high temperatures. Key life governing variables in these models include temperature, stress, initial strength, oxygen partial pressure, and total pressure. These models are described in this paper.

  6. Three-Axis Distributed Fiber Optic Strain Measurement in 3D Woven Composite Structures

    NASA Technical Reports Server (NTRS)

    Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

    2013-01-01

    Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading. Keywords: fiber optic, distributed strain sensing, Rayleigh scatter, optical frequency domain reflectometry

  7. Composition and analysis of a model waste for a CELSS (Controlled Ecological Life Support System)

    NASA Technical Reports Server (NTRS)

    Wydeven, T. J.

    1983-01-01

    A model waste based on a modest vegetarian diet is given, including composition and elemental analysis. Its use is recommended for evaluation of candidate waste treatment processes for a Controlled Ecological Life Support System (CELSS).

  8. Aging behavior and life prediction of graphite composites

    NASA Technical Reports Server (NTRS)

    Ramohalli, Kumar; Raasch, David

    1989-01-01

    This paper presents experimental data from two independent tests, designed to determine the long-term reliability of composite materials. The technique of accelerated aging at elevated temperatures is employed. In the first set, graphite fiber, epoxy composites in five ply layups are manufactured and tested in the standard short-beam shear mode. In the second set, Nomex honeycomb, graphite fiber/epoxy composite face and rear sheet sandwich coupons are tested. After satisfying simple consistency checks, data interpretation is attempted within the framework of an Arrhenius degradation model. The elevated temperature is assumed to influence the degradation according to this temperature-dependent rate law. From these tests on five-ply composites and honeycomb sandwiches, it is concluded that aging is not a serious problem.

  9. Aerosol size distribution, composition, and CO2 backscatter

    NASA Technical Reports Server (NTRS)

    Clarke, Antony D.; Porter, John N.

    1991-01-01

    The aerosol size distribution, composition, and CO2 backscatter at 10.6 microns (beta-CO2) were measured continuosly at the Mauna Loa Observatory (Hawaii) during January-March and November-December, 1988 periods to compare the characteristics of periods associated with appreciable Asian dust transport to that site (January-March) with those of periods characterized by low-dust condition. The aerosol size distribution in the range 0.15 micron to 7.6 microns was measured at temperatures of 40, 150, and 340 C to differentiate between volatile and nonvolatile aerosols. Large ranges of variability was found in measurements of aerosol size distribution during both periods, but the average distributions were similar for both the high-dust and the low-dust periods. However, values for beta-CO2 were more elevated (by about six times) during periods associated with active Asian dust transport to the observatory site than during the low-dust periods.

  10. Carbon nanofiber polymer composites: evaluation of life cycle energy use.

    PubMed

    Khanna, Vikas; Bakshi, Bhavik R

    2009-03-15

    Holistic evaluation of emerging nanotechnologies using systems analysis is pivotal for guiding their safe and sustainable development. While toxicity studies of engineered nanomaterials are essential, understanding of the potential large scale impacts of nanotechnology is also critical for developing sustainable nanoproducts. This work evaluates the life cycle energetic impact associated with the production and use of carbon nanofiber (CNF) reinforced polymer nanocomposites (PNC). Specifically, both simple CNF and carbon nanofiber-glass fiber (CNF-GF) hybrid PNCs are evaluated and compared with steel for equal stiffness design. Life cycle inventory is developed based on published literature and best available engineering information. A cradle-to-gate comparison suggests that for equal stiffness design, CNF reinforced PNCs are 1.6-12 times more energy intensive than steel. It is anticipated that the product use phase may strongly influence whether any net savings in life cycle energy consumption can be realized. A case study involving the use of CNF and CNF-GF reinforced PNCs in the body panels of automobiles highlights that the use of PNCs with lower CNF loading ratios has the potential for net life cycle energy savings relative to steel owing to improved fuel economy benefits. Other factors such as cost, toxicity impact of CNF, and end-of-life issues specific to CNFs need to be considered to evaluate the final economic and environmental performance of CNF reinforced PNC materials. PMID:19368217

  11. Waste tire derived carbon-polymer composite paper as pseudocapacitive electrode with long cycle life

    SciTech Connect

    Boota, M.; Paranthaman, Mariappan Parans; Naskar, Amit K.; Gogotsi, Yury; Li, Yunchao; Akato, Kokouvi

    2015-09-25

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m2/g–1) is synthesized using waste tires as the precursor and used as supercapacitor electrode. The narrow pore size distribution (PSD) and high surface area led to a good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI/TC). The composite film was highly flexible, conductive and exhibited a capacitance of 480 F/g–1 at 1 mV/s–1 with excellent capacitance retention up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life were ascribed to the short diffusional paths, uniform PANI coating and tight confinement of the PANI in the inner pores of the tire-derived carbon via - interactions, which minimized the degradation of the PANI upon cycling. Here, we anticipate that the same strategy can be applied to deposit other pseudocapacitive materials with low-cost TC to achieve even higher electrochemical performance and longer cycle life, a key challenge for redox active polymers.

  12. Waste Tire Derived Carbon-Polymer Composite Paper as Pseudocapacitive Electrode with Long Cycle Life.

    PubMed

    Boota, M; Paranthaman, M Parans; Naskar, Amit K; Li, Yunchao; Akato, Kokouvi; Gogotsi, Y

    2015-11-01

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m(2)  g(-1)) is synthesized using waste tires as the precursor and used as a supercapacitor electrode material. The narrow pore-size distribution and high surface area led to good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI). The composite paper was highly flexible, conductive, and exhibited a capacitance of 480 F g(-1) at 1 mV s(-1) with excellent capacitance retention of up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life were ascribed to the short diffusional paths, uniform PANI coating, and tight confinement of the PANI in the inner pores of the tire-derived carbon through π-π interactions, which minimized the degradation of the PANI upon cycling. We anticipate that the same strategy can be applied to deposit other pseudocapacitive materials to achieve even higher electrochemical performance and longer cycle life-a key challenge for redox active polymers. PMID:26404735

  13. Waste tire derived carbon-polymer composite paper as pseudocapacitive electrode with long cycle life

    DOE PAGESBeta

    Boota, M.; Paranthaman, Mariappan Parans; Naskar, Amit K.; Gogotsi, Yury; Li, Yunchao; Akato, Kokouvi

    2015-09-25

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m2/g–1) is synthesized using waste tires as the precursor and used as supercapacitor electrode. The narrow pore size distribution (PSD) and high surface area led to a good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI/TC). The composite film was highly flexible, conductive and exhibited a capacitance of 480 F/g–1 at 1 mV/s–1 with excellent capacitance retention up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life weremore » ascribed to the short diffusional paths, uniform PANI coating and tight confinement of the PANI in the inner pores of the tire-derived carbon via - interactions, which minimized the degradation of the PANI upon cycling. Here, we anticipate that the same strategy can be applied to deposit other pseudocapacitive materials with low-cost TC to achieve even higher electrochemical performance and longer cycle life, a key challenge for redox active polymers.« less

  14. Body composition in infancy: impact on health later in life

    Technology Transfer Automated Retrieval System (TEKTRAN)

    From retrospective studies, there is substantial evidence that birthweight and the rate of weight gain during early infancy are associated with increased risk for adverse health outcomes later in life. Birthweight is the marker of the integrative effects of the prenatal environment, while the rate o...

  15. Chemical Composition of Fine Particulate Matter and Life Expectancy

    PubMed Central

    Dominici, Francesca; Wang, Yun; Correia, Andrew W.; Ezzati, Majid; Pope, C. Arden; Dockery, Douglas W.

    2016-01-01

    Background In a previous study, we provided evidence that a decline in fine particulate matter (PM2.5) air pollution during the period between 2000 and 2007 was associated with increased life expectancy in 545 counties in the United States. In this article, we investigated which chemical constituents of PM2.5 were the main drivers of the observed association. Methods We estimated associations between temporal changes in seven major components of PM2.5 (ammonium, sulfate, nitrate, elemental carbon matter, organic carbon matter, sodium, and silicon) and temporal changes in life expectancy in 95 counties between 2002 and 2007. We included US counties that had adequate chemical components of PM2.5 mass data across all seasons. We fitted single pollutant and multiple pollutant linear models, controlling for available socioeconomic, demographic, and smoking variables and stratifying by urban and nonurban counties. Results In multiple pollutant models, we found that: (1) a reduction in sulfate was associated with an increase in life expectancy; and (2) reductions in ammonium and sodium ion were associated with increases in life expectancy in nonurban counties only. Conclusions Our findings suggest that recent reductions in long-term exposure to sulfate, ammonium, and sodium ion between 2002 and 2007 are associated with improved public health. PMID:25906366

  16. The life, death, and composition of exoterrestrial planets around intermediate mass stars

    NASA Astrophysics Data System (ADS)

    Melis, Carl Anthony

    This thesis attempts to comprehensively address the life, death, and composition of terrestrial-like planets orbiting around intermediate-mass stars. All-sky optical and infrared catalogs were cross-correlated to identify new main sequence stellar systems with evidence for terrestrial planet zone formation and evolution events. One such system is identified and its mid- infrared spectral energy distribution is characterized. In the course of cross- correlating the all-sky catalogs a new class of dusty, accreting, first-ascent giant star was discovered. Rough characterization of this new class of giants in the optical and infrared is provided with an emphasis on two giant-disk systems. The final throes of planetary systems around intermediate mass stars were investigated through the study of three gas-disk hosting white dwarfs. A dusty component to one white dwarf is identified, and the physical parameters regarding all three disks are determined. A model for the gas disk heating mechanism is suggested. By examining the pollution of the white dwarf photosphere by infalling disk material the first-ever bulk composition of an extra-solar rocky body is determined.

  17. Trends in the Diversity, Distribution and Life History Strategy of Arctic Hydrozoa (Cnidaria)

    PubMed Central

    Ronowicz, Marta; Kukliński, Piotr; Mapstone, Gillian M.

    2015-01-01

    This is the first attempt to compile a comprehensive and updated species list for Hydrozoa in the Arctic, encompassing both hydroid and medusa stages and including Siphonophorae. We address the hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic by Hydrozoa after the Last Glacial Maximum. Presence-absence data of Hydrozoa in the Arctic were prepared on the basis of historical and present-day literature. The Arctic was divided into ecoregions. Species were grouped into distributional categories according to their worldwide occurrences. Each species was classified according to life history strategy. The similarity of species composition among regions was calculated with the Bray-Curtis index. Average and variation in taxonomic distinctness were used to measure diversity at the taxonomic level. A total of 268 species were recorded. Arctic-boreal species were the most common and dominated each studied region. Nineteen percent of species were restricted to the Arctic. There was a predominance of benthic species over holo- and meroplanktonic species. Arctic, Arctic-Boreal and Boreal species were mostly benthic, while widely distributed species more frequently possessed a pelagic stage. Our results support hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic. The predominance of benthic Hydrozoa suggests that the Arctic could have been colonised after the Last Glacial Maximum by hydroids rafting on floating substrata or recolonising from glacial refugia. PMID:25793294

  18. Three-axis distributed fiber optic strain measurement in 3D woven composite structures

    NASA Astrophysics Data System (ADS)

    Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

    2013-03-01

    Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading.

  19. Ionic Conduction in Lithium Ion Battery Composite Electrode Governs Cross-sectional Reaction Distribution.

    PubMed

    Orikasa, Yuki; Gogyo, Yuma; Yamashige, Hisao; Katayama, Misaki; Chen, Kezheng; Mori, Takuya; Yamamoto, Kentaro; Masese, Titus; Inada, Yasuhiro; Ohta, Toshiaki; Siroma, Zyun; Kato, Shiro; Kinoshita, Hajime; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2016-01-01

    Composite electrodes containing active materials, carbon and binder are widely used in lithium-ion batteries. Since the electrode reaction occurs preferentially in regions with lower resistance, reaction distribution can be happened within composite electrodes. We investigate the relationship between the reaction distribution with depth direction and electronic/ionic conductivity in composite electrodes with changing electrode porosities. Two dimensional X-ray absorption spectroscopy shows that the reaction distribution is happened in lower porosity electrodes. Our developed 6-probe method can measure electronic/ionic conductivity in composite electrodes. The ionic conductivity is decreased for lower porosity electrodes, which governs the reaction distribution of composite electrodes and their performances. PMID:27193448

  20. Asteroid taxonomy and the distribution of the compositional types

    NASA Technical Reports Server (NTRS)

    Zellner, B.

    1979-01-01

    Physical observations of minor planets documented in the TRIAD computer file are used to classify 752 objects into the broad compositional types C, S, M, E, R, and U (unclassifiable) according to the prescriptions adopted by Bowell et al. (1978). Diameters are computed from the photometric magnitude using radiometric and/or polarimetric data where available, or else from albedos characteristic of the indicated type. An analysis of the observational selection effects leads to tabulation of the actual number of asteroids, as a function of type and diameter, in each of 15 orbital element zones. For the whole main belt the population is 75% of type C, 15% of type S, and 10% of other types, with no belt-wide dependence of the mixing ratios on diameter. In some zones the logarithmic diameter-frequency relations are decidedly nonlinear. The relative frequency of S-type objects decreases smoothly outward through the main belt, with exponential scale length 0.5 AU. The rarer types show a more chaotic, but generally flatter, distribution over distance. Characteristic type distributions, contrasting with the background population, are found for the Eos, Koronis, Nysa and Themis families.

  1. Strain and composition distribution study under high pressure at nanoscale

    NASA Astrophysics Data System (ADS)

    Yang, W.

    2012-12-01

    Over last decades, both synchrotron radiation techniques and high pressure research have made great progress. Advanced synchrotron capabilities with high spatial resolution, high flux, high energy resolution and high coherence provides us many new avenues to conduct advanced high pressure researches. In this talk, we will mainly focus on the new developments of the nanoscale imaging techniques on the internal strain distribution and chemical composition mapping in three dimensions. Coherence of the synchrotron beam for high pressure community has been largely ignored due to the complicated sample environment for data interpolation. We have developed a practical "Mutual Coherence Function" to overcome the influence from the sample condition and extrapolated the full coherent diffraction imaging results from a single crystal nanoparticle. The 3d internal strain evolution as a function of applied pressure shows clearly the nanoscale plastic flow cross the nanograin and provides us fundamental deformation mechanism of individual nanocrystal under pressure. The advanced synchrotron optics also provides us tens of nanometer scale 3d tomography resolution, which in return provides detail structural characterization of materials at extreme conditions. By choosing incident x-ray energy near absorption edge, the individual element distribution can be mapped at nanometer scale, which provides us the capability of watching chemical reaction, dissociation, and even valence change under high pressure. Several new experimental results will be presented and outlook will be discussed.

  2. Durability and Life of Ceramic Matrix Composites in Combustion Environment

    NASA Technical Reports Server (NTRS)

    Tewari, Surendra

    1997-01-01

    It is now generally recognized that the next frontier in the commercial air travel will be achieved by an optimum combination of the concepts being used for the air and space transports. It will depend upon the new engines specifically designed to meet the demanding strength, temperature, environment and economy requirements. The successful development of an advanced propulsion system for a 21st Century High Speed Civil Transport will require key advances in the combustor system. Minimizing nitrous oxide (NO(x)) emission is critical, since the deleterious interaction within the ozone layer would occur at the proposed vehicle cruise level of about 75,000 feet. In order to achieve the low NOx levels an efficient combustor operating at controlled equivalence ratios and high combustion temperatures are required. This requires a combustor, whose one portion will be operating in an oxidizing environment while the other portion will operate in a reducing environment. This rather unusual requirement has introduced considerable challenge to the materials scientists and engineers, the development of material systems capable of long-life at high temperatures (up to 3000 F) in an oxidizing and/or reducing environment.

  3. Fuel Distribution Estimate via Spin Period to Precession Period Ratio for the Advanced Composition Explorer

    NASA Technical Reports Server (NTRS)

    DeHart, Russell; Smith, Eric; Lakin, John

    2015-01-01

    The spin period to precession period ratio of a non-axisymmetric spin-stabilized spacecraft, the Advanced Composition Explorer (ACE), was used to estimate the remaining mass and distribution of fuel within its propulsion system. This analysis was undertaken once telemetry suggested that two of the four fuel tanks had no propellant remaining, contrary to pre-launch expectations of the propulsion system performance. Numerical integration of possible fuel distributions was used to calculate moments of inertia for the spinning spacecraft. A Fast Fourier Transform (FFT) of output from a dynamics simulation was employed to relate calculated moments of inertia to spin and precession periods. The resulting modeled ratios were compared to the actual spin period to precession period ratio derived from the effect of post-maneuver nutation angle on sun sensor measurements. A Monte Carlo search was performed to tune free parameters using the observed spin period to precession period ratio over the life of the mission. This novel analysis of spin and precession periods indicates that at the time of launch, propellant was distributed unevenly between the two pairs of fuel tanks, with one pair having approximately 20% more propellant than the other pair. Furthermore, it indicates the pair of the tanks with less fuel expelled all of its propellant by 2014 and that approximately 46 kg of propellant remains in the other two tanks, an amount that closely matches the operational fuel accounting estimate. Keywords: Fuel Distribution, Moments of Inertia, Precession, Spin, Nutation

  4. Energy, ecology and the distribution of microbial life

    PubMed Central

    Macalady, Jennifer L.; Hamilton, Trinity L.; Grettenberger, Christen L.; Jones, Daniel S.; Tsao, Leah E.; Burgos, William D.

    2013-01-01

    Mechanisms that govern the coexistence of multiple biological species have been studied intensively by ecologists since the turn of the nineteenth century. Microbial ecologists in the meantime have faced many fundamental challenges, such as the lack of an ecologically coherent species definition, lack of adequate methods for evaluating population sizes and community composition in nature, and enormous taxonomic and functional diversity. The accessibility of powerful, culture-independent molecular microbiology methods offers an opportunity to close the gap between microbial science and the main stream of ecological theory, with the promise of new insights and tools needed to meet the grand challenges humans face as planetary engineers and galactic explorers. We focus specifically on resources related to energy metabolism because of their direct links to elemental cycling in the Earth's history, engineering applications and astrobiology. To what extent does the availability of energy resources structure microbial communities in nature? Our recent work on sulfur- and iron-oxidizing autotrophs suggests that apparently subtle variations in the concentration ratios of external electron donors and acceptors select for different microbial populations. We show that quantitative knowledge of microbial energy niches (population-specific patterns of energy resource use) can be used to predict variations in the abundance of specific taxa in microbial communities. Furthermore, we propose that resource ratio theory applied to micro-organisms will provide a useful framework for identifying how environmental communities are organized in space and time. PMID:23754819

  5. The chemical composition and distribution of interstellar grains

    NASA Technical Reports Server (NTRS)

    Greenberg, J. M.; Hong, S.-S.

    1974-01-01

    The chemical composition of interstellar grains is derived here on the basis of (1) the cosmic abundance of the elements; (2) the wavelength dependence of extinction and polarization; (3) the average total extinction; (4) the ratio of polarization to extinction; (5) the predominantly dielectric character of grains in the visible spectral region; and (6) infrared spectral characteristics of grains. Inferences of the core-mantle model with respect to spatial distribution are consistent with the proposition that growth of the mantles occurs in the galactic shock region predicted by the density-wave theory. Estimates of the total visual extinction toward the galactic center and the consequent estimates of the total amount of far infrared radiation are shown to depend critically on the grain model. Variations of the ratio of far ultraviolet to visual extinction are correlated with the conditions for growth of mantles on the bare small particles which are generally prevented from accreting mantles primarily because of their extreme temperature fluctuations produced by the ultraviolet photons in the radiation field.

  6. Altered potassium channel distribution and composition in myelinated axons suppresses hyperexcitability following injury

    PubMed Central

    Calvo, Margarita; Richards, Natalie; Schmid, Annina B; Barroso, Alejandro; Zhu, Lan; Ivulic, Dinka; Zhu, Ning; Anwandter, Philipp; Bhat, Manzoor A; Court, Felipe A; McMahon, Stephen B; Bennett, David LH

    2016-01-01

    Neuropathic pain following peripheral nerve injury is associated with hyperexcitability in damaged myelinated sensory axons, which begins to normalise over time. We investigated the composition and distribution of shaker-type-potassium channels (Kv1 channels) within the nodal complex of myelinated axons following injury. At the neuroma that forms after damage, expression of Kv1.1 and 1.2 (normally localised to the juxtaparanode) was markedly decreased. In contrast Kv1.4 and 1.6, which were hardly detectable in the naïve state, showed increased expression within juxtaparanodes and paranodes following injury, both in rats and humans. Within the dorsal root (a site remote from injury) we noted a redistribution of Kv1-channels towards the paranode. Blockade of Kv1 channels with α-DTX after injury reinstated hyperexcitability of A-fibre axons and enhanced mechanosensitivity. Changes in the molecular composition and distribution of axonal Kv1 channels, therefore represents a protective mechanism to suppress the hyperexcitability of myelinated sensory axons that follows nerve injury. DOI: http://dx.doi.org/10.7554/eLife.12661.001 PMID:27033551

  7. Testing and Life Prediction for Composite Rotor Hub Flexbeams

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.

    2004-01-01

    A summary of several studies of delamination in tapered composite laminates with internal ply-drops is presented. Initial studies used 2D FE models to calculate interlaminar stresses at the ply-ending locations in linear tapered laminates under tension loading. Strain energy release rates for delamination in these laminates indicated that delamination would likely start at the juncture of the tapered and thin regions and grow unstably in both directions. Tests of glass/epoxy and graphite/epoxy linear tapered laminates under axial tension delaminated as predicted. Nonlinear tapered specimens were cut from a full-size helicopter rotor hub and were tested under combined constant axial tension and cyclic transverse bending loading to simulate the loading experienced by a rotorhub flexbeam in flight. For all the tested specimens, delamination began at the tip of the outermost dropped ply group and grew first toward the tapered region. A 2D FE model was created that duplicated the test flexbeam layup, geometry, and loading. Surface strains calculated by the model agreed very closely with the measured surface strains in the specimens. The delamination patterns observed in the tests were simulated in the model by releasing pairs of MPCs along those interfaces. Strain energy release rates associated with the delamination growth were calculated for several configurations and using two different FE analysis codes. Calculations from the codes agreed very closely. The strain energy release rate results were used with material characterization data to predict fatigue delamination onset lives for nonlinear tapered flexbeams with two different ply-dropping schemes. The predicted curves agreed well with the test data for each case studied.

  8. Concept for Determining the Life of Ceramic Matrix Composites Using Nondestructive Characterization Techniques

    NASA Technical Reports Server (NTRS)

    Effinger, Michael; Ellingson, Bill; Spohnholtz, Todd; Koenig, John

    2000-01-01

    Damping measurements have been taken on ceramic matrix composite (CMC) turbopump blisks in the as fabricated, post proof testing, and post turbopump testing conditions. These results indicate that damping is able to quantify fatigue of the CMC blisk. This gives hope for the potential of determining the actual and residual life of CMC materials using a combination of nondestructive techniques. If successful, then this new paradigm for life prediction of CMCs could revolutionize the approach for designing and servicing CMC components, thereby significantly reducing costs for design, development, health monitoring, and maintenance of CMC components and systems. The Nondestructive Characterization (NDC) life prediction approach would complement life prediction using micromechanics and continuum finite element models. This paper reports on the initial concept of NDC life prediction and how changes in damping and ultrasonic elastic modulus data have established the concept as a possibility.

  9. Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller Bearings

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2012-01-01

    The effect of internal clearance on radially loaded deepgroove ball and cylindrical roller bearing load distribution and fatigue life was determined for four clearance groups defined in the bearing standards. The analysis was extended to negative clearance (interference) conditions to produce a curve of life factor versus internal clearance. Rolling-element loads can be optimized and bearing life maximized for a small negative operating clearance. Life declines gradually with positive clearance and rapidly with increasing negative clearance. Relationships were found between bearing life and internal clearance as a function of ball or roller diameter, adjusted for load. Results are presented as life factors for radially loaded bearings independent of bearing size or applied load. In addition, a modified Stribeck Equation is presented that relates the maximum rolling-element load to internal bearing clearance.

  10. Physical Activity, Body Composition, and Perceived Quality of Life of Adults with Visual Impairments

    ERIC Educational Resources Information Center

    Holbrook, Elizabeth A.; Caputo, Jennifer L.; Perry, Tara L.; Fuller, Dana K.; Morgan, Don W.

    2009-01-01

    Relatively little is known about the health and fitness of adults with visual impairments. This article documents the physical activity levels and body-composition profiles of young and middle-aged adults with visual impairments and addresses the concomitant effects of these factors on perceived quality of life. (Contains 2 tables.)

  11. Prediction of creep-rupture life of unidirectional titanium matrix composites subjected to transverse loading

    SciTech Connect

    John, R.; Khobaib, M.; Smith, P.R.

    1996-10-01

    Titanium matrix composites (TMCs) incorporating unidirectional fiber reinforcement are considered as enabling materials technology for advanced engines which require high specific strength and elevated temperature capability. The resistance of unidirectional TMCs to deformation under longitudinally applied sustained loading at elevated temperatures has been well documented. Many investigators have shown that the primary weakness of the unidirectional TMC is its susceptibility to failure under very low transverse loads, especially under sustained loading. Hence, a reliable model is required to predict the creep-rupture life of TMCs subjected to different transverse stress levels over a wide range of temperatures. In this article, the authors propose a model to predict the creep-rupture life of unidirectional TMC subjected to transverse loading based on the creep-rupture life of unidirectional TMC subjected to transverse loading based on the creep-rupture behavior of the corresponding fiberless matrix. The model assumes that during transverse loading, the effective load-carrying matrix ligament along a row of fibers controls the creep-rupture strength and the fibers do not contribute to the creep resistance of the composite. The proposed model was verified using data obtained from different TMC fabricated using three matrix compositions, which exhibited distinctly different types of creep behavior. The results show that the creep-rupture life of the transverse TMC decreases linearly with increasing ratio of the fiber diameter to the ply thickness. The creep-rupture life is also predicted to be independent of fiber spacing along the length of the specimen.

  12. Strength and fatigue life evaluation of composite laminate with embedded sensors

    NASA Astrophysics Data System (ADS)

    Rathod, Vivek T.; Hiremath, S. R.; Roy Mahapatra, D.

    2014-04-01

    Prognosis regarding durability of composite structures using various Structural Health Monitoring (SHM) techniques is an important and challenging topic of research. Ultrasonic SHM systems with embedded transducers have potential application here due to their instant monitoring capability, compact packaging potential toward unobtrusiveness and noninvasiveness as compared to non-contact ultrasonic and eddy current techniques which require disassembly of the structure. However, embedded sensors pose a risk to the structure by acting as a flaw thereby reducing life. The present paper focuses on the determination of strength and fatigue life of the composite laminate with embedded film sensors like CNT nanocomposite, PVDF thin films and piezoceramic films. First, the techniques of embedding these sensors in composite laminates is described followed by the determination of static strength and fatigue life at coupon level testing in Universal Testing Machine (UTM). Failure mechanisms of the composite laminate with embedded sensors are studied for static and dynamic loading cases. The coupons are monitored for loading and failure using the embedded sensors. A comparison of the performance of these three types of embedded sensors is made to study their suitability in various applications. These three types of embedded sensors cover a wide variety of applications, and prove to be viable in embedded sensor based SHM of composite structures.

  13. Creep rupture life prediction of short fiber-reinforced metal matrix composites

    SciTech Connect

    Nam, H.W.; Han, K.S.

    1998-07-01

    The creep rupture life of an Al/Al{sub 2}O{sub 3} composite and its creep behavior were studied. The metal matrix composite was produced by using a squeeze casting technique. High-temperature tensile tests and creep experiments were conducted on a 15 vol pct alumina fiber-reinforced AC2B Al alloy metal matrix composite (MMC). The high-temperature tensile strength of Al/Al{sub 2}O{sub 3} composite is 14 pct higher than that of an AC2B Al alloy. The steady-state creep rate and the creep life were measured. The stress exponent in Norton`s equation and the activation energy were computed. The stress exponents of the AC2B and Al/Al{sub 2}O{sub 3} composites were found to be 4 and 12.3, respectively. The activation energy of the AC2B and Al/Al{sub 2}O{sub 3} composites were found to be 242.74 and 465.35 kJ/mol, respectively. A new equation for predicting creep life was established, which was based on the conservation of the creep strain energy. The theoretical predictions were compared with those of the experiment results, and a good agreement was obtained. It was found that the creep life is inversely proportional to the (n + 1)th power of the applied stress and strain failure energy of creep is conserved. The creep fracture surface, examined by scanning electron microscopy (SEM), showed that the MMC specimen failed in a brittle manner.

  14. Integrated spectral energy distributions of binary star composite stellar populations

    NASA Astrophysics Data System (ADS)

    Li, Zhongmu; Zhang, Liyun; Liu, Jinzhong

    2012-08-01

    This paper presents the theoretically integrated spectral energy distributions (SEDs) of binary star composite stellar populations (bsCSPs) in early-type galaxies and how the bsCSP model can be used for the spectral studies of galaxies. All bsCSPs are built based on three adjustable inputs (metallicity, ages of old and young components). The effects of binary interactions and stellar population mixture are taken into account. The results show some ultraviolet (UV) upturn SEDs naturally for bsCSPs. The SEDs of bsCSPs are affected obviously by all of the three stellar population parameters, and the effects of three parameters are degenerate. This suggests that the effects of metallicity, and the ages of the old (major in stellar mass) and young (minor) components of stellar populations should be taken into account in the SED studies of early-type galaxies. The sensitivities of SEDs at different wavelengths to the inputs of a stellar population model are also investigated. It is shown that UV SEDs are sensitive to all of the three stellar population parameters, rather than to only stellar age. Special wavelength ranges according to some SED features that are relatively sensitive to the stellar metallicity, young-component age and old-component age of bsCSPs are found by this work. For example, the shapes of SEDs with the wavelength ranges of 5110-5250, 5250-5310, 5310-5350, 5830-5970 and 20 950-23 550 Å are relatively sensitive to the stellar metallicity of bsCSPs. The shapes of SEDs within 965-985, 1005-1055 and 1205-1245 Å are sensitive to the old-component age, while SED features within the wavelength ranges of 2185-2245, 2455-2505, 2505-2555, 2775-2825 and 2825-2875 Å are sensitive to the young-component age. The results suggest that some line indices within these special wavelength ranges are possibly better for stellar population studies compared to the others, and greater weights may be given to these special SED parts in the determination of the stellar population parameters of early-type galaxies from fitting SEDs via bsCSPs.

  15. 25 CFR 179.101 - How does the Secretary distribute principal and income to the holder of a life estate?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Distribute any contract bonus one-half each to the life tenant and the remainderman; (3) In the case of... the holder of a life estate? 179.101 Section 179.101 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under...

  16. 25 CFR 179.101 - How does the Secretary distribute principal and income to the holder of a life estate?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Distribute any contract bonus one-half each to the life tenant and the remainderman; (3) In the case of... the holder of a life estate? 179.101 Section 179.101 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under...

  17. Probabilistic Residual Strength Model Developed for Life Prediction of Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Thomas, David J.; Verrilli, Michael J.; Calomino, Anthony M.

    2004-01-01

    For the next generation of reusable launch vehicles, NASA is investigating introducing ceramic matrix composites (CMCs) in place of current superalloys for structural propulsion applications (e.g., nozzles, vanes, combustors, and heat exchangers). The higher use temperatures of CMCs will reduce vehicle weight by eliminating and/or reducing cooling system requirements. The increased strength-to-weight ratio of CMCs relative to superalloys further enhances their weight savings potential. However, in order to provide safe designs for components made of these new materials, a comprehensive life prediction methodology for CMC structures needs to be developed. A robust methodology for lifing composite structures has yet to be adopted by the engineering community. Current industry design practice continues to utilize deterministic empirically based models borrowed from metals design for predicting material life capabilities. The deterministic nature of these models inadequately addresses the stochastic character of brittle composites, and their empirical reliance makes predictions beyond the experimental test conditions a risky extrapolation. A team of engineers at the NASA Glenn Research Center has been developing a new life prediction engineering model. The Probabilistic Residual Strength (PRS) model uses the residual strength of the composite as its damage metric. Expected life and material strength are both considered probabilistically to account for the observed stochastic material response. Extensive experimental testing has been carried out on C/SiC (a candidate aerospace CMC material system) in a controlled 1000 ppm O2/argon environment at elevated temperatures of 800 and 1200 C. The test matrix was established to allow observation of the material behavior, characterization of the model, and validation of the model's predictive capabilities. Sample results of the validation study are illustrated in the graphs.

  18. Effect of carbide distribution on rolling-element fatigue life of AMS 5749

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Bamberger, E. N.

    1983-01-01

    Endurance tests with ball bearings made of corrosion resistant bearing steel which resulted in fatigue lives much lower than were predicted are discussed. Metallurgical analysis revealed an undesirable carbide distribution in the races. It was shown in accelerated fatigue tests in the RC rig that large, banded carbides can reduce rolling element fatigue life by a factor of approximately four. The early spalling failures on the bearing raceways are attributed to the large carbide size and banded distribution.

  19. Electrical Resistance of Ceramic Matrix Composites for Damage Detection and Life-Prediction

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Morscher, Gregory N.; Xia, Zhenhai

    2008-01-01

    The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection or inspection of a component during "down time". The correlation of damage with appropriate failure mechanism can then be applied to accurate life prediction for high-temperature ceramic matrix composites.

  20. [Distribution and species composition of hyporheic macroinvertebrates in a mountain stream].

    PubMed

    Zhang, Yue-wei; Yuan, Xing-zhong; Liu, Hong; Ren, Hai-qing; Deng, Wei; Wang, Xiao-feng

    2015-09-01

    Hyporheic macroinvertebrates are an important component of stream ecosystem. The composition and distribution of the hyporheic macroinvertebrates were investigated using artificial substrates in the upper reaches of Heishuitan River in August, December 2013 and April 2014. The results indicated that a total of 27 microinvertbrate species were identified in all three seasons. In summer, 22 species were identified, accounting for 81.8% of aquatic insects. 16 species were identified both in winter and spring, accounting for 75.0% and 62.5% of aquatic insects, respectively. The density of macroinvertebrate assemblage was significantly lower in summer than in winter and spring, and was the highest in spring. The biomass of macroinvertebrate assemblage was significantly higher in winter than in summer and spring, and was the lowest in summer. Species richness, Shannon index and Pielou index all had no significant difference among the three seasons. The density and richness of macroinvertebrates decreased with bed depth, and the maximum invertebrate density was found within the top 20 cm of the stream bed. Collector-filterer and collector-gatherer were the dominant functional feeding group in all three seasons. The community structure and temporal-spatial distribution of macroinvertebrates were determined by interactions and life history strategy of macroinvertebrates, and physical-chemical factors of hyporheic zone. PMID:26785569

  1. The galactic habitable zone and the age distribution of complex life in the Milky Way.

    PubMed

    Lineweaver, Charles H; Fenner, Yeshe; Gibson, Brad K

    2004-01-01

    We modeled the evolution of the Milky Way Galaxy to trace the distribution in space and time of four prerequisites for complex life: the presence of a host star, enough heavy elements to form terrestrial planets, sufficient time for biological evolution, and an environment free of life-extinguishing supernovae. We identified the Galactic habitable zone (GHZ) as an annular region between 7 and 9 kiloparsecs from the Galactic center that widens with time and is composed of stars that formed between 8 and 4 billion years ago. This GHZ yields an age distribution for the complex life that may inhabit our Galaxy. We found that 75% of the stars in the GHZ are older than the Sun. PMID:14704421

  2. Identification of Heredity Kernels and Their Influence on the Life Time of Glass/Polyester Composites

    NASA Astrophysics Data System (ADS)

    Olodo, E. T.; Adjovi, E. C.; Adanhounme, V.

    2014-11-01

    One of the major problems encountered in prediction of hereditary viscoelastic behavior of polymeric composites is the determination of heredity kernels. This issue comes down to identification of the model characterizing the viscoelastic properties of these materials. The purpose of this work is to propose a model for prediction of viscoelastic nonlinear behavior of laminate composite with polyester matrix, through the study and analysis of heredity kernels and their influence on the life time of this material. Identification of this model required experimental determination at room temperature, of viscoelastic parameters of heredity kernels by macroscopic approach. These data provide predictive tools for establishment of the life time and long term stress limit under static complex loading for this type of material.

  3. Fatigue life prediction of an intermetallic matrix composite at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Bartolotta, Paul A.

    1991-01-01

    A strain-based fatigue life prediction method is proposed for an intermetallic matrix composite (IMC) under tensile cyclic loadings at elevated temperatures. Styled after the Universal Slopes method, the model utilizes the composite's tensile properties to estimate fatigue life. Factors such as fiber volume ratio, number of plys and temperature dependence are implicitly incorporated into the model through these properties. The model constants are determined by using unidirectional fatigue data at temperatures of 425 and 815 C. Fatigue lives from two independent sources are used to verify the model at temperatures of 650 and 760 C. Cross-ply lives at 760 C are also predicted. It is demonstrated that the correlation between experimental and predicted lives is within a factor of two.

  4. Primary igneous rocks on Mars: Composition and distribution

    NASA Technical Reports Server (NTRS)

    Singer, Robert B.; Mcsween, Harry Y., Jr.

    1991-01-01

    The present knowledge of the crustal composition of Mars is synthesized and implications discussed for in-situ resource utilization. Sources of information include remote sensing observations, Viking XRF chemical measurements, and characteristics of the SNC meteorites (which most researchers now believe originated on Mars). There are a number of lines of evidence that abundant ferrous-iron rich igneous crustal rocks (and derivative soils) are available at or very near the current Martian surface at many locations on the planet. Most of these exposures show spectroscopic evidence for abundant pyroxene, consistent with basaltic compositions. The SNC meteorites, which have basaltic compositions, were also studied extensively. Interpretations of Mars crustal chemistry and mineralogy (petrology) based on these various sources are reviewed, and their consistencies and differences are discussed.

  5. Residual Strain Distribution in Bent Composite Boiler Tubes

    SciTech Connect

    Hubbard, Camden R; Gorti, Sarma B; Tang, Fei

    2006-01-01

    Kraft recovery boilers are typically constructed of carbon steel boiler tubes clad with a corrosion resistant layer, and these composite tubes are bent and welded together to form air port panels which enable the combustion air to enter the boiler. In this paper, the through-thickness residual strain in the carbon steel layer of non-heat-treated and heat-treated composite bent tubes were measured by neutron diffraction techniques and modeled by finite element modeling. The results can be used to optimize material selection and manufacturing processes to prevent stress corrosion and corrosion fatigue cracking in the boiler tubes.

  6. Erosion Coatings Developed to Increase the Life and Durability of Composites

    NASA Technical Reports Server (NTRS)

    Sutter, James K.; Naik, Subhash K.; Bowman, Cheryl L.; Siefker, Robert; Miyoshi, Kazuhisa; Perusek, Gail P.

    2004-01-01

    Both the NASA Glenn Research Center and the Allison Advanced Development Company (AADC) have worked to develop and demonstrate erosion-resistant coatings that would increase the life and durability of composite materials used in commercial aircraft engines. These composite materials reduce component weight by 20 to 30 percent and result in less fuel burn and emissions and more fuel savings. Previously, however, their use was limited because of poor erosion resistance, which causes concerns about safety and leads to high maintenance costs. The coatings were tested by the University of Cincinnati, and the composites were manufactured by Texas Composites and coated by Engelhard and NASA Glenn. Rolls-Royce Corporation uses composite materials, which are stronger and less dense than steel or titanium, to make bypass vanes for their AE3007 engines. These engines are widely used in regional jet aircraft (Embraer) and unmanned air vehicles such as the Northrop Grumman Global Hawk. Coatings developed by NASA/Rolls-Royce can reduce erosion from abrasive materials and from impurities in the air that pass over these vanes, allowing Rolls-Royce to take advantage of the benefits of composite materials over titanium without the added costs of increased maintenance and/or engine failure. The Higher Operating Temperature Propulsion Components (HOTPC) Project developed cost-effective, durable coatings as part of NASA's goal to increase aviation system capacity growth. These erosion coatings will reduce the number of special inspections or instances of discontinued service due to erosion, allowing aircraft capacity to be maintained without inconveniencing the traveling public. A specific example of extending component life showed that these coatings increased the life of graphite fiber and polymer composite bypass vanes up to 8 times over that of the uncoated vanes. This increased durability allows components to operate to full design life without the fear of wear or failure. Recently, Rolls-Royce completed over 2000 hr of engine testing with the coated fan exit bypass vanes. There was no loss of coating after nearly 5000 typical engine cycles. Midway through the engine tests, the coated vanes were removed from the engine during a scheduled maintenance and inspection period. The vanes were shipped back to Glenn, where they underwent further stress testing in the Structural Dynamics Lab, mimicking more extreme conditions than those typical of the AE3007 engine cycle. These vanes were then replaced in the AE3007 and subjected to another 1000 hr of engine tests. Once again, there was no loss of coating and only a minimal appearance of cracking.

  7. Design of intelligent composites with life-cycle health management capabilities

    NASA Astrophysics Data System (ADS)

    Rosania, Colleen L.; Larrosa, Cecilia C.; Chang, Fu-Kuo

    2015-03-01

    Use of carbon fiber reinforced polymers (CFRPs) presents challenges because of their complex manufacturing processes and different damage mechanics in relation to legacy metal materials. New monitoring methods for manufacturing, quality verification, damage estimation, and prognosis are needed to use CFRPs safely and efficiently. This work evaluates the development of intelligent composite materials using integrated piezoelectric sensors to monitor the material during cure and throughout service life. These sensors are used to propagate ultrasonic waves through the structure for health monitoring. During manufacturing, data is collected at different stages during the cure cycle, detecting the changing material properties during cure and verifying quality and degree of cure. The same sensors can then be used with previously developed techniques to perform damage detection, such as impact detection and matrix crack density estimation. Real-time damage estimation can be combined with prognostic models to predict future propagation of damage in the material. In this work experimental results will be presented from composite coupons with embedded piezoelectric sensors. Cure monitoring and damage detection results derived from analysis of the ultrasonic sensor signal will be shown. Sensitive signal parameters to the different stimuli in both the time and frequency domains will be explored for this analysis. From these results, use of the same sensor networks from manufacturing throughout the life of the composite material will demonstrate the full life-cycle monitoring capability of these intelligent materials.

  8. Influence of Weight Gain Rate on Early Life Nutritional Status and Body Composition of Children

    PubMed Central

    Magalhães, Taís Cristina Araújo; Ribeiro, Andréia Queiroz; Priore, Silvia Eloiza; Franceschini, Sylvia do Carmo Castro; Sant'Ana, Luciana Ferreira da Rocha

    2014-01-01

    Objective. To evaluate the influence of the weight gain rate at 4–6 months on nutritional status and body composition in children between 4 and 7 years of age. Methods. Retrospective cohort study, sample of 257 children. Data collection was performed in two stages, with the first relating to retrospective data of weight gain from birth to the first 4–6 months of life in the patient records. Measurements of weight, height, waist circumference, and body composition in children between ages 4 and 7 years were obtained. Nutritional status was assessed by the BMI/age. Control variables, such as pregnancy, breastfeeding, lifestyle, and sociodemographics, were studied. Descriptive analysis and multiple linear regression were performed. Results. In the nutritional status assessment, the prevalence of overweight observed was 24.9%. After adjusting for control variables, it was found that the increase of the WGR at 4–6 months of age explained the occurrence of higher BMI/age, percentage of total body fat, body fat percentage in the android region, and waist circumference in children between 4 and 7 years of age. Conclusion. The increase of the WGR in the first months of life can lead to the occurrence of higher values of parameters of nutritional status and body composition in later life. PMID:25538953

  9. Elemental composition and size distribution of particulates in Cleveland, Ohio

    NASA Technical Reports Server (NTRS)

    King, R. B.; Fordyce, J. S.; Neustadter, H. E.; Leibecki, H. F.

    1975-01-01

    Measurements were made of the elemental particle size distribution at five contrasting urban environments with different source-type distributions in Cleveland, Ohio. Air quality conditions ranged from normal to air pollution alert levels. A parallel network of high-volume cascade impactors (5-state) were used for simultaneous sampling on glass fiber surfaces for mass determinations and on Whatman-41 surfaces for elemental analysis by neutron activation for 25 elements. The elemental data are assessed in terms of distribution functions and interrelationships and are compared between locations as a function of resultant wind direction in an attempt to relate the findings to sources.

  10. Microstructural Influence on Deformation and Fatigue Life of Composites Using the Generalized Method of Cells

    NASA Technical Reports Server (NTRS)

    Arnold, S. M.; Murthy, P.; Bednarcyk, B. A.; Pineda, E. J.

    2015-01-01

    A fully coupled deformation and damage approach to modeling the response of composite materials and composite laminates is presented. It is based on the semi-­-analytical generalized method of cells (GMC) micromechanics model as well as its higher fidelity counterpart, HFGMC, both of which provide closed-form constitutive equations for composite materials as well as the micro scale stress and strain fields in the composite phases. The provided constitutive equations allow GMC and HFGMC to function within a higher scale structural analysis (e.g., finite element analysis or lamination theory) to represent a composite material point, while the availability of the micro fields allow the incorporation of lower scale sub­-models to represent local phenomena in the fiber and matrix. Further, GMC's formulation performs averaging when applying certain governing equations such that some degree of microscale field accuracy is surrendered in favor of extreme computational efficiency, rendering the method quite attractive as the centerpiece in a integrated computational material engineering (ICME) structural analysis; whereas HFGMC retains this microscale field accuracy, but at the price of significantly slower computational speed. Herein, the sensitivity of deformation and the fatigue life of graphite/epoxy PMC composites, with both ordered and disordered microstructures, has been investigated using this coupled deformation and damage micromechanics based approach. The local effects of fiber breakage and fatigue damage are included as sub-models that operate on the microscale for the individual composite phases. For analysis of laminates, classical lamination theory is employed as the global or structural scale model, while GMC/HFGMC is embedded to operate on the microscale to simulate the behavior of the composite material within each laminate layer. A key outcome of this study is the statistical influence of microstructure and micromechanics idealization (GMC or HFGMC) on the overall accuracy of unidirectional and laminated composite deformation and fatigue response.

  11. Bayesian Analysis of Step-Stress Accelerated Life Test with Exponential Distribution

    SciTech Connect

    Lee, J.; Pan, R.

    2012-04-01

    In this article, we propose a general Bayesian inference approach to the step-stress accelerated life test with type II censoring. We assume that the failure times at each stress level are exponentially distributed and the test units are tested in an increasing order of stress levels. We formulate the prior distribution of the parameters of life-stress function and integrate the engineering knowledge of product failure rate and acceleration factor into the prior. The posterior distribution and the point estimates for the parameters of interest are provided. Through the Markov chain Monte Carlo technique, we demonstrate a nonconjugate prior case using an industrial example. It is shown that with the Bayesian approach, the statistical precision of parameter estimation is improved and, consequently, the required number of failures could be reduced.

  12. Distributed multifunctional sensor network for composite structural state sensing

    NASA Astrophysics Data System (ADS)

    Qing, Xinlin P.; Wang, Yishou; Gao, Limin; Kumar, Amrita

    2012-04-01

    Advanced fiber reinforced composite materials are becoming the main structural materials of next generation of aircraft because of their high strength and stiffness to weight ratios, and strong designability. In order to take full advantages of composite materials, there is a need to develop an embeddable multifunctional sensing system to allow a structure to "feel" and "think" its structural state. In this paper, the concept of multifunctional sensor network integrated with a structure, similar to the human nervous system, has been developed. Different types of network sensors are permanently integrated within a composite structure to sense structural strain, temperature, moisture, aerodynamic pressure; monitor external impact on the structure; and detect structural damages. Utilizing this revolutionary concept, future composite structures can be designed and manufactured to provide multiple modes of information, so that the structures have the capabilities for intelligent sensing, environmental adaptation and multi-functionality. The challenges for building such a structural state sensing system and some solutions to address the challenges are also discussed in the paper.

  13. The Galactic Habitable Zone and the Age Distribution of Complex Life in the Milky Way

    NASA Astrophysics Data System (ADS)

    Lineweaver, Charles

    2007-05-01

    Prerequisites for complex life are not uniformly distributed in our Galaxy. These prerequisites include: Enough heavy elements to form terrestrial planets, sufficient time for biological evolution and an environment free of life-extinguishing supernovae. We have modelled the evolution of the Milky Way to trace the distribution in space and time of these prerequisites. We identify the Galactic Habitable Zone (GHZ) as an annular region between 7 and 9 kiloparsecs from the galactic centre that widens with time and is composed of stars that formed between 8 and 4 billion years ago. This zone of habitability is small in the sense that it encompasses less than 10% of the stars ever formed in the Milky Way. We obtain an age distribution for the stars in the GHZ and thus an age distribution for the complex life that may inhabit our Galaxy. We find that 3/4 of the stars in the GHZ are older than the Earth and that their mean age is 1 Gyr older than the Earth. I will discuss ways in which the luminosity and spectrum of electromagnetic radiation can affect the molecular evolution that we believe led to biogenesis.

  14. Validation of Framework Code Approach to a Life Prediction System for Fiber Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Gravett, Phillip

    1997-01-01

    The grant was conducted by the MMC Life Prediction Cooperative, an industry/government collaborative team, Ohio Aerospace Institute (OAI) acted as the prime contractor on behalf of the Cooperative for this grant effort. See Figure I for the organization and responsibilities of team members. The technical effort was conducted during the period August 7, 1995 to June 30, 1996 in cooperation with Erwin Zaretsky, the LERC Program Monitor. Phil Gravett of Pratt & Whitney was the principal technical investigator. Table I documents all meeting-related coordination memos during this period. The effort under this grant was closely coordinated with an existing USAF sponsored program focused on putting into practice a life prediction system for turbine engine components made of metal matrix composites (MMC). The overall architecture of the NMC life prediction system was defined in the USAF sponsored program (prior to this grant). The efforts of this grant were focussed on implementing and tailoring of the life prediction system, the framework code within it and the damage modules within it to meet the specific requirements of the Cooperative. T'he tailoring of the life prediction system provides the basis for pervasive and continued use of this capability by the industry/government cooperative. The outputs of this grant are: 1. Definition of the framework code to analysis modules interfaces, 2. Definition of the interface between the materials database and the finite element model, and 3. Definition of the integration of the framework code into an FEM design tool.

  15. Corrosion in a distribution system: Steady water and its composition.

    PubMed

    Nawrocki, Jacek; Raczyk-Stanisławiak, Urszula; Swietlik, Joanna; Olejnik, Anna; Sroka, Mirosława J

    2010-03-01

    Corrosion processes in drinking water distribution systems have been investigated for years. This paper proves the existence of a layer of steady water surrounding and partly filling corrosion scale in corroded water pipes. It is expected that steady water may substantially influence the corrosion. The idea of steady water explains why longer retention times would lead to more turbid waters containing more suspended Fe oxides (hydroxides). During stagnation period stagnant water mixes partially with steady water and the compensation of ions' concentration as well as particle diffusion is observed. Steady water is rich in ions and has reductive properties causing quick disappearance of nitrates and unwanted ammonia formation. Ammonia in turn may be responsible for fast oxygen and chlorine decay in the distribution system due to nitrification. Nitrates may also undergo denitrification in steady water, i.e. they would support bacterial existence in the distribution system. Such an environment makes favourable conditions for sulphate reducing bacteria and in fact in all of the steady water samples we have detected sulphides. Moreover, our results have shown that considerable amounts of assimilable organic carbon (AOC) can be formed in the corroded distribution system. PMID:20053415

  16. Surface composition and barium evaporation rate of ``pedigreed'' impregnated tungsten dispenser cathodes during accelerated life testing

    NASA Astrophysics Data System (ADS)

    Tomich, D. H.; Mescher, J. A.; Grant, J. T.

    1987-03-01

    A study has been made of the surface composition and barium evaporation rate of "pedigreed" impregnated tungsten dispenser cathodes. The effect of air exposure on coated cathodes was examined and was found to have no significant effect on barium evaporation rate although in some cases longer reactivation times were required. No changes in surface topography were apparent following air exposure and reactivation. Life testing was done at 100°C above the typical operating temperature for the cathode, where the typical operating temperature was taken to be 950°C for coated cathodes and 1050°C for uncoated cathodes. The cathodes were examined at different stages of life testing, up to 1200 h. Significant decreases in barium evaporation rates were found after as few as 500 h of life testing. After 1000 h the evaporation rate had decreased more than an order of magnitude. Changes in surface composition were also found. The effects of tungsten particle size, used in manufacture of the billet, on barium evaporation rate were also studied but no correlation was found.

  17. Bridging porous Si-C composites with conducting agents for improving battery cycle life

    NASA Astrophysics Data System (ADS)

    Li, Zhenzhen; Wang, Wei; Li, Zhihu; Qin, Zhihong; Wang, Jun; Liu, Zhaoping

    2015-07-01

    Porous silicon-carbon (Si-C) composites have been considered to be one of the most effective architectures to improve the cycle life of Si based anode because of its native ability to accommodate the large volume change during discharge/charge process. It is found that lots of reported porous Si-C electrodes employed large amount of binder materials to enhance the structural stability which significantly decreased gravimetric capacity of the whole electrode with limited active materials. In this work, without loss of active materials, various conducting agents were used to build electrical bridges between porous Si-C composites, which significantly improved the structural stability and hence the cycle life. Due to the increase of connection possibilities, cycle life of zero-dimensional MCMB bridged electrode reaches 80 cycles with a capacity retention of 80%, and it can be further promoted to 200 cycles for the VGCF bridged electrode and 220 cycles for the rGO bridged electrode. This work paves an effective route to construct stable Si electrode with porous structures as building blocks without the decrease of active materials.

  18. Distribution, ecology, life history, genetic variation, and risk of extinction of nonhuman primates from Costa Rica.

    PubMed

    Zaldívar, Maria E; Rocha, Oscar; Glander, Kenneth E; Aguilar, Gabriel; Huertas, Ana S; Sánchez, Ronald; Wong, Grace

    2004-09-01

    We examined the association between geographic distribution, ecological traits, life history, genetic diversity, and risk of extinction in nonhuman primate species from Costa Rica. All of the current nonhuman primate species from Costa Rica are included in the study; spider monkeys (Ateles geoffroyi), howling monkeys (Alouatta palliata), capuchins (Cebus capucinus), and squirrel monkeys (Saimiri oerstedii). Geographic distribution was characterized accessing existing databases. Data on ecology and life history traits were obtained through a literature review. Genetic diversity was characterized using isozyme electrophoresis. Risk of extinction was assessed from the literature. We found that species differed in all these traits. Using these data, we conducted a Pearson correlation between risk of extinction and ecological and life history traits, and genetic variation, for widely distributed species. We found a negative association between risk of extinction and population birth and growth rates; indicating that slower reproducing species had a greater risk of extinction. We found a positive association between genetic variation and risk of extinction; i.e., species showing higher genetic variation had a greater risk of extinction. The relevance of these traits for conservation efforts is discussed. PMID:17361561

  19. Quantifying distributed damage in composites via the thermoelastic effect

    SciTech Connect

    Mahoney, B.J.

    1992-01-01

    A new approach toward quantifying transverse matrix cracking in composite laminates using the thermoelastic effect is developed. The thermoelastic effect refers to the small temperature changes that are generated in components under dynamic loading. Two models are derived, and the theoretical predictions are experimentally verified for three types of laminates. Both models include damage-induced changes in the lamina stress state and lamina coefficients of thermal expansion conduction effects, and epoxy thickness. The first model relates changes in the laminate TSA signal to changes in longitudinal laminate stiffness and Poisson's ratio. This model is based on gross simplifying assumptions and can be used on any composite laminate layup undergoing transverse matrix cracking. The second model relates TSA signal changes to longitudinal laminate stiffness, Poisson's ratio, and microcrack density for (0[sub p]90[sub q])[sub s] and (90[sub q]/0[sub p])[sub s] cross-ply laminates. Both models yield virtually identical results for the cross-ply laminates considered. A sensitivity analysis is performed on both models to quantify the effects of reasonable property variations on the normalized stiffness vs. normalized TSA signal results for the three laminates under consideration. The results for the cross-ply laminates are very insensitive, while the (+/- 45)[sub 5s] are particularly sensitive to epoxy thickness and longitudinal lamina coefficient of thermal expansion. Experiments are conducted on (0[sub 3]/90[sub 3])[sub s] and (90[sub 3]/0[sub 3])[sub s] Gl/Ep laminates and (+/- 45)[sub 5s] Gr/Ep laminates to confirm the theoretical developments of the thesis. There is a very good correlation between the theoretical predictions and experimental results for the Gl/Ep laminates.

  20. Using gamma distribution to determine half-life of rotenone, applied in freshwater.

    PubMed

    Rohan, Maheswaran; Fairweather, Alastair; Grainger, Natasha

    2015-09-15

    Following the use of rotenone to eradicate invasive pest fish, a dynamic first-order kinetic model is usually used to determine the half-life and rate at which rotenone dissipated from the treated waterbody. In this study, we investigate the use of a stochastic gamma model for determining the half-life and rate at which rotenone dissipates from waterbodies. The first-order kinetic and gamma models produced similar values for the half-life (4.45 days and 5.33 days respectively) and days to complete dissipation (51.2 days and 52.48 days respectively). However, the gamma model fitted the data better and was more flexible than the first-order kinetic model, allowing us to use covariates and to predict a possible range for the half-life of rotenone. These benefits are particularly important when examining the influence that different environmental factors have on rotenone dissipation and when trying to predict the rate at which rotenone will dissipate during future operations. We therefore recommend that in future the gamma distribution model is used when calculating the half-life of rotenone in preference to the dynamic first-order kinetics model. PMID:25965037

  1. Behavioural early-life exposures and body composition at age 15 years

    PubMed Central

    Leary, S D; Lawlor, D A; Davey Smith, G; Brion, M J; Ness, A R

    2015-01-01

    Background/Objectives: Previous studies have demonstrated associations between some early-life exposures and later obesity, but most have used body mass index in childhood or adulthood as the outcome. The objective of this study was to investigate whether early-life exposures were associated with directly measured fat and lean mass in adolescence. Subjects/Methods: This study used data on 4750 mother–offspring pairs, collected as a part of the Avon Longitudinal Study of Parents and Children, Bristol, UK between 1991 and 1992; associations between behavioural exposures occurring from conception up to 5 years of age (maternal and paternal smoking during pregnancy, breastfeeding, age at introduction to solids, dietary patterns and physical inactivity during early childhood) and offspring body composition measured by dual-energy X-ray absorptiometry at ~15 years were assessed. Results: After full adjustment for potential confounders, maternal smoking during pregnancy, having a junk food diet and spending more time watching television in early childhood were all associated with higher fat mass at age 15, whereas maternal smoking, having a healthy diet and playing computer games more frequently in early childhood were all associated with a higher lean mass at age 15. Associations with paternal smoking were generally weaker for both fat and lean mass, but as there was no strong statistical evidence for maternal vs paternal differences, confounding by social factors rather than a direct effect of maternal smoking cannot be ruled out. Early feeding was not associated with fat or lean mass at age 15. Conclusions: This study does not provide compelling evidence for associations between most early-life factors and body composition in adolescence. However, possible associations with dietary patterns and physical inactivity in early childhood require further investigation in other cohorts that have direct measurements of adolescent body composition. PMID:25664839

  2. Kinetics of Formation of Molecular Weight Distribution of Epoxy Composite

    NASA Astrophysics Data System (ADS)

    Komar, Lyudmila A.; Kondyurin, Alexey; Svistkov, Alexander L.

    Curing of epoxy matrix prepreg in free space environment is a complex problem. A simulation of the chemical reaction, evaporation and radiation effects in the matrix is a way to understand and predict the curing process. We have developed a mathematical apparatus of the epoxy resin kinetics in term of molecular weight distribution (MWD), which includes the polymerization mechanism of bifunctional epoxy and sixfunctional triethylenetetraamine (TETA) molecules. The mathematical model for a number of molecules with the mass m at time t is based on the following equation $ beta(t,m)=m_{am} / m sum(6}_{i=0) alpha(am) _i (t,m)+ m_{ep} / m sum(2}_{i=0) alpha(ep) _i (t,m), where m_{am} and m_{ep} are the masses of one amine block and one epoxy block, respectively; alpha^{am}_i (t,m) is the MWD near the TETA blocks with the chemical bonds i at time t for the mass values m>0; alpha_i^{ep}(t,m) is the MWD parameters of the epoxy blocks with chemical bonds i at time t for the mass values m>0. For the distribution densities alpha^{am}_i (t,m) and alpha_i^{ep}(t,m), we propose the differential system of equations, which has been solved by applying boundary conditions which are based on the results of chromatography and infrared spectroscopy measurements of the epoxy matrix having different concentration of the hardener. For the initial MWD we accept a Gaussian distribution with parameters alpha^{am}_0 (t,m_1) =146 amu, alpha_0^{ep}(t,m_1) =340 amu and alpha_1^{ep}(t,m_1) =624 amu. Dispersion of the molecular weight for the initial distribution equals to 25 amu. A portion of TETA molecules in the fraction was 25%, and the portion of epoxy molecules with i=0 and i=1 was 67.5% and 7.5%$, respectively. Solutions were obtained at mass step equals to 5 amu and at time step equals to 0.25 min over the interval from 0 to 500 min. The model gives a full kinetic of MWD during the curing reaction. The study is supported by the RFBR (grants N 12-08-00970-a and N 14-08-96011-r-ural-a).

  3. Composition of Bacterial Communities Associated with Aurelia aurita Changes with Compartment, Life Stage, and Population

    PubMed Central

    Weiland-Bräuer, Nancy; Neulinger, Sven C.; Pinnow, Nicole; Künzel, Sven; Baines, John F.

    2015-01-01

    The scyphozoan Aurelia aurita is recognized as a key player in marine ecosystems and a driver of ecosystem change. It is thus intensely studied to address ecological questions, although its associations with microorganisms remain so far undescribed. In the present study, the microbiota associated with A. aurita was visualized with fluorescence in situ hybridization (FISH) analysis, and community structure was analyzed with respect to different life stages, compartments, and populations of A. aurita by 16S rRNA gene amplicon sequencing. We demonstrate that the composition of the A. aurita microbiota is generally highly distinct from the composition of communities present in ambient water. Comparison of microbial communities from different developmental stages reveals evidence for life stage-specific community patterns. Significant restructuring of the microbiota during strobilation from benthic polyp to planktonic life stages is present, arguing for a restructuring during the course of metamorphosis. Furthermore, the microbiota present in different compartments of the adult medusa (exumbrella mucus and gastric cavity) display significant differences, indicating body part-specific colonization. A novel Mycoplasma strain was identified in both compartment-specific microbiota and is most likely present inside the epithelium as indicated by FISH analysis of polyps, indicating potential endosymbiosis. Finally, comparison of polyps of different populations kept under the same controlled laboratory conditions in the same ambient water showed population-specific community patterns, most likely due the genetic background of the host. In conclusion, the presented data indicate that the associated microbiota of A. aurita may play important functional roles, e.g., during the life cycle. PMID:26116680

  4. Composition of Bacterial Communities Associated with Aurelia aurita Changes with Compartment, Life Stage, and Population.

    PubMed

    Weiland-Bräuer, Nancy; Neulinger, Sven C; Pinnow, Nicole; Künzel, Sven; Baines, John F; Schmitz, Ruth A

    2015-09-01

    The scyphozoan Aurelia aurita is recognized as a key player in marine ecosystems and a driver of ecosystem change. It is thus intensely studied to address ecological questions, although its associations with microorganisms remain so far undescribed. In the present study, the microbiota associated with A. aurita was visualized with fluorescence in situ hybridization (FISH) analysis, and community structure was analyzed with respect to different life stages, compartments, and populations of A. aurita by 16S rRNA gene amplicon sequencing. We demonstrate that the composition of the A. aurita microbiota is generally highly distinct from the composition of communities present in ambient water. Comparison of microbial communities from different developmental stages reveals evidence for life stage-specific community patterns. Significant restructuring of the microbiota during strobilation from benthic polyp to planktonic life stages is present, arguing for a restructuring during the course of metamorphosis. Furthermore, the microbiota present in different compartments of the adult medusa (exumbrella mucus and gastric cavity) display significant differences, indicating body part-specific colonization. A novel Mycoplasma strain was identified in both compartment-specific microbiota and is most likely present inside the epithelium as indicated by FISH analysis of polyps, indicating potential endosymbiosis. Finally, comparison of polyps of different populations kept under the same controlled laboratory conditions in the same ambient water showed population-specific community patterns, most likely due the genetic background of the host. In conclusion, the presented data indicate that the associated microbiota of A. aurita may play important functional roles, e.g., during the life cycle. PMID:26116680

  5. Sequence composition of disordered regions fine-tunes protein half-life

    PubMed Central

    Fishbain, Susan; Inobe, Tomonao; Israeli, Eitan; Chavali, Sreenivas; Yu, Houqing; Kago, Grace; Babu, M. Madan; Matouschek, Andreas

    2015-01-01

    The proteasome controls the concentrations of most proteins in eukaryotic cells. It recognizes its protein substrates through ubiquitin tags and initiates degradation at disordered regions within the substrate. Here we find that the proteasome has pronounced preferences for the amino acid sequence composition of the regions at which it initiates degradation. Specifically, proteins where the initiation regions have biased amino acid compositions show longer half-lives in yeast. The relationship is also observed on a genomic scale in mouse cells. These preferences affect the degradation rates of proteins in vitro, can explain the unexpected stability of natural proteins in yeast, and may affect the accumulation of toxic proteins in disease. We propose that the proteasome’s sequence preferences provide a second component to the degradation code and may fine-tune protein half-life in cells. PMID:25643324

  6. Composite Weibull-Inverse Transformed Gamma distribution and its actuarial application

    NASA Astrophysics Data System (ADS)

    Maghsoudi, Mastoureh; Bakar, Shaiful Anuar Abu; Hamzah, Nor Aishah

    2014-07-01

    This paper introduces a new composite model, namely, composite Weibull-Inverse Transformed Gamma distribution which assumes Weibull distribution for the head up to a specified threshold and inverse transformed gamma distribution beyond it. The closed form of probability density function (pdf) as well as the estimation of parameters by maximum likelihood method is presented. The model is compared with several benchmark distributions and their performances are measured. A well-known data set, Danish fire loss data, is used for this purpose and it's Value at Risk (VaR) using the new model is computed. In comparison to several standard models, the composite Weibull- Inverse Transformed Gamma model proved to be a competitor candidate.

  7. Modeling and life prediction methodology for Titanium Matrix Composites subjected to mission profiles

    SciTech Connect

    Mirdamadi, M.; Johnson, W.S.

    1994-08-01

    Titanium matrix composites (TMC) are being evaluated as structural materials for elevated temperature applications in future generation hypersonic vehicles. In such applications, TMC components are subjected to complex thermomechanical loading profiles at various elevated temperatures. Therefore, thermomechanical fatigue (TMF) testing, using a simulated mission profile, is essential for evaluation and development of life prediction methodologies. The objective of the research presented in this paper was to evaluate the TMF response of the (0/90)2s SCS-6/Timetal-21S subjected to a generic hypersonic flight profile and its portions with a temperature ranging from -130 C to 816 C. It was found that the composite modulus, prior to rapid degradation, had consistent values for all the profiles tested. A micromechanics based analysis was used to predict the stress-strain response of the laminate and of the constituents in each ply during thermomechanical loading conditions by using only constituent properties as input. The fiber was modeled as elastic with transverse orthotropic and temperature dependent properties. The matrix was modeled using a thermoviscoplastic constitutive relation. In the analysis, the composite modulus degradation was assumed to result from matrix cracking and was modeled by reducing the matrix modulus. Fatigue lives of the composite subjected to the complex generic hypersonic flight profile were well correlated using the predicted stress in 0 degree fibers.

  8. Modeling and life prediction methodology for Titanium Matrix Composites subjected to mission profiles

    NASA Technical Reports Server (NTRS)

    Mirdamadi, M.; Johnson, W. S.

    1994-01-01

    Titanium matrix composites (TMC) are being evaluated as structural materials for elevated temperature applications in future generation hypersonic vehicles. In such applications, TMC components are subjected to complex thermomechanical loading profiles at various elevated temperatures. Therefore, thermomechanical fatigue (TMF) testing, using a simulated mission profile, is essential for evaluation and development of life prediction methodologies. The objective of the research presented in this paper was to evaluate the TMF response of the (0/90)2s SCS-6/Timetal-21S subjected to a generic hypersonic flight profile and its portions with a temperature ranging from -130 C to 816 C. It was found that the composite modulus, prior to rapid degradation, had consistent values for all the profiles tested. A micromechanics based analysis was used to predict the stress-strain response of the laminate and of the constituents in each ply during thermomechanical loading conditions by using only constituent properties as input. The fiber was modeled as elastic with transverse orthotropic and temperature dependent properties. The matrix was modeled using a thermoviscoplastic constitutive relation. In the analysis, the composite modulus degradation was assumed to result from matrix cracking and was modeled by reducing the matrix modulus. Fatigue lives of the composite subjected to the complex generic hypersonic flight profile were well correlated using the predicted stress in 0 degree fibers.

  9. Long-term mechanical life testing of polymeric post insulators for distribution and a comparison to porcelain

    SciTech Connect

    Cherney, E.A. )

    1988-07-01

    The paper presents the results and analyses of long-term cantilever strength tests on polymeric line post insulators. The time-to-failure data for static cantilever loads are represented by the Weibull distribution. The life distribution, obtained from the maximum likelihood estimates of the accelerated failure times, fits an exponential model. An extrapolation of the life distribution to normal loads provides an estimate of the strength rating and mechanical equivalence to porcelain line post insulators.

  10. Corona Characteristics of Distribution Line in Contact with Conductive Material and Life Estimation of Conductor Insulation

    NASA Astrophysics Data System (ADS)

    Yamashita, Takahiko; Fujishima, Tomoyuki; Kuba, Hiroyuki

    In relation to the accidents due to bird nests in contact with overhead distribution lines, the authors investigated on life estimation of conductor insulation. The accident is often caused by crow or magpie. There is a region in which magpie is being specified to the protected bird in Japan. In that region, the nest in the breeding season can not be removed easily. Recently, metal wires are used for the nest material. When this conductive material is in contact with the distribution line and the arm, corona discharge will occur. The conductor insulation of the distribution line receives deterioration and there is a possibility of causing the accident. In this study, acceleration test was done to examine time from nest building to causing the accident in the distribution line. The acceleration factor based on the charge amount of corona and the influence of the applied voltage on corona characteristics were discussed. Moreover, the life of the conductor insulation was discussed from the V-t characteristics and the acceleration factor.

  11. Distribution patterns of different carbon nanostructures in silicon nitride composites.

    PubMed

    Tapasztó, Orsolya; Markó, Márton; Balázsi, Csaba

    2012-11-01

    The dispersion properties of single- and multi-walled carbon nanotubes as well as mechanically exfoliated few layer graphene flakes within the silicon nitride ceramic matrix have been investigated. Small angle neutron scattering experiments have been employed to gain information on the dispersion of the nano-scale carbon fillers throughout the entire volume of the samples. The neutron scattering data combined with scanning electron microscopy revealed strikingly different distribution patterns for different types of carbon nanostructures. The scattering intensities for single wall carbon nanotubes (SWCNTs) reveal a decay exponent characteristic to surface fractals, which indicate that the predominant part of nanotubes can be found in loose networks wrapping the grains of the polycrystalline matrix. By contrast, multi wall carbon nanotubes (MWCNTs) were found to be present mainly in the form of bulk aggregate structures, while few-layer graphene (FLG) flakes have been individually dispersed within the host matrix, under the very same preparation and processing conditions. PMID:23421284

  12. Distinctive life traits and distribution along environmental gradients of dominant and subordinate Mediterranean ant species.

    PubMed

    Arnan, Xavier; Cerdá, Xim; Retana, Javier

    2012-10-01

    For most animal and plant species, life traits strongly affect their species-specific role, function or position within ecological communities. Previous studies on ant communities have mostly focused on the role of dominant species and the outcome of interspecific interactions. However, life traits of ant species have seldom been considered within a community framework. This study (1) analyses life traits related to ecological and behavioural characteristics of dominant and subordinate ant species from 13 sites distributed throughout the Iberian Peninsula, (2) determines how similar the ant species are within each of the two levels of the dominance hierarchy, and (3) establishes the distribution patterns of these different groups of species along environmental gradients. Our results showed that the differences between dominants and subordinates fall into two main categories: resource exploitation and thermal tolerance. Dominant species have more populated colonies and defend food resources more fiercely than subordinates, but they display low tolerance to high temperatures. We have identified different assemblages of species included within each of these two levels in the dominance hierarchy. The distribution of these assemblages varied along the environmental gradient, shifting from dominant Dolichoderinae and cryptic species in moist areas, to dominant Myrmicinae and hot climate specialists mainly in open and hot sites. We have been able to identify a set of life traits of the most common Iberian ant species that has enabled us to characterise groups of dominant and subordinate species. Although certain common features within the groups of both dominants and subordinates always emerge, other different features allow for differentiating subgroups within each of these groups. These different traits allow the different subgroups coping with particular conditions across environmental gradients. PMID:22476711

  13. Identifying the failure mechanism in accelerated life tests by two-parameter lognormal distributions

    NASA Astrophysics Data System (ADS)

    Chunsheng, Guo; Yanfeng, Zhang; Ning, Wan; Hui, Zhu; Shiwei, Feng

    2014-08-01

    The failure mechanism stimulated by accelerated stress in the degradation may be different from that under normal conditions, which would lead to invalid accelerated life tests. To solve the problem, we study the relation between the Arrhenius equation and the lognormal distribution in the degradation process. Two relationships of the lognormal distribution parameters must be satisfied in the conclusion of the unaltered failure mechanism, the first is that the logarithmic standard deviations must be equivalent at different temperature levels, and the second is that the ratio of the differences between logarithmic means must be equal to the ratio of the differences between reciprocals of temperature. The logarithm of distribution lines must simultaneously have the same slope and regular interval lines. We studied the degradation of thick-film resistors in MCM by accelerated stress at four temperature levels (390, 400, 410 and 420 K), and the result agreed well with our method.

  14. Perchlorate in The Great Lakes: Distribution, Isotopic Composition and Origin

    NASA Astrophysics Data System (ADS)

    Poghosyan, A.; Sturchio, N. C.; Jackson, W. A.; Guan, Y.; Eiler, J. M.; Hatzinger, P. B.

    2013-12-01

    Concentrations, stable chlorine and oxygen isotopic compositions, and 36Cl abundances of perchlorate were investigated in the five Laurentian Great Lakes. Samples were collected during monitoring cruises in 2007 and 2008 of the U.S. EPA's RV Lake Guardian and in 2010 at the water supply intake of Marquette, MI on the southern shore of Lake Superior. Concentrations of perchlorate were measured by IC/MS/MS at 24 locations, including one or two depth profiles in each lake. Mean concentrations (μg/L) are: Superior, 0.06 × 0.01; Michigan, 0.10 × 0.01; Huron, 0.11 × 0.01; Erie, 0.08 × 0.01, and Ontario, 0.09 × 0.01. Concentration vs. depth is nearly constant in each lake, indicating well-mixed conditions. Perchlorate was extracted from near-surface water by passing 15,000 to 80,000 L of water through 1-L cartridges containing Purolite A530E bifunctional anion-exchange resin. In the laboratory, perchlorate was eluted from the resin, purified, and precipitated as a >99% pure crystalline phase. Milligram amounts were recovered from each lake. Chlorine and oxygen isotopic analyses were performed at Caltech using the Cameca 7f-GEO SIMS instrument, following validation of the SIMS method with analyses of USGS-37 and USGS-38 isotopic reference materials. Results indicate a relatively narrow range in δ37Cl values (+2.9 to +3.9 ‰) and a wider range in δ18O values (-4.0 to +4.1 ‰), with a general geographic trend of increasing δ18O from west to east. Oxygen-17 was measured at UIC using dual-inlet IRMS of O2 produced by decomposition of KClO4. Great Lakes perchlorate has mass-independent oxygen isotopic variations with positive Δ17O values (+1.6 ‰ to +2.7 ‰) divided into two distinct groups: Lake Superior (+2.7 ‰) and the other four lakes (~ +1.7 ‰). The isotopic data indicate that perchlorate is dominantly of natural origin, having stable isotopic compositions resembling those of perchlorate from pre-industrial groundwaters in the western USA. The 36Cl/Cl ratios decrease from Lake Superior (66,500×10-15) to Lake Ontario (7,400×10-15). The high 36Cl/Cl ratios in the lakes having longer water residence times may be explained by retention of perchlorate formed during the time of the 36Cl bomb pulse (1952-1964). Mass balance of perchlorate indicates that substantial biodegradation or uptake of perchlorate may occur in Lake Erie. 36Cl/Cl results confirm that perchlorate in the Great Lakes has dominantly natural origin. These data provide better constraints on possible perchlorate source(s), mixing proportions, and isotopic exchange or fractionation processes within the lakes, as well as better estimates of the regional atmospheric deposition flux of perchlorate and the 36Cl abundance of bomb-pulse perchlorate.

  15. Characterization of Cyanobacterial Hydrocarbon Composition and Distribution of Biosynthetic Pathways

    PubMed Central

    Coates, R. Cameron; Podell, Sheila; Korobeynikov, Anton; Lapidus, Alla; Pevzner, Pavel; Sherman, David H.; Allen, Eric E.; Gerwick, Lena; Gerwick, William H.

    2014-01-01

    Cyanobacteria possess the unique capacity to naturally produce hydrocarbons from fatty acids. Hydrocarbon compositions of thirty-two strains of cyanobacteria were characterized to reveal novel structural features and insights into hydrocarbon biosynthesis in cyanobacteria. This investigation revealed new double bond (2- and 3-heptadecene) and methyl group positions (3-, 4- and 5-methylheptadecane) for a variety of strains. Additionally, results from this study and literature reports indicate that hydrocarbon production is a universal phenomenon in cyanobacteria. All cyanobacteria possess the capacity to produce hydrocarbons from fatty acids yet not all accomplish this through the same metabolic pathway. One pathway comprises a two-step conversion of fatty acids first to fatty aldehydes and then alkanes that involves a fatty acyl ACP reductase (FAAR) and aldehyde deformylating oxygenase (ADO). The second involves a polyketide synthase (PKS) pathway that first elongates the acyl chain followed by decarboxylation to produce a terminal alkene (olefin synthase, OLS). Sixty-one strains possessing the FAAR/ADO pathway and twelve strains possessing the OLS pathway were newly identified through bioinformatic analyses. Strains possessing the OLS pathway formed a cohesive phylogenetic clade with the exception of three Moorea strains and Leptolyngbya sp. PCC 6406 which may have acquired the OLS pathway via horizontal gene transfer. Hydrocarbon pathways were identified in one-hundred-forty-two strains of cyanobacteria over a broad phylogenetic range and there were no instances where both the FAAR/ADO and the OLS pathways were found together in the same genome, suggesting an unknown selective pressure maintains one or the other pathway, but not both. PMID:24475038

  16. Constituent-Based Life Models Being Developed for SiC/SiC Composites

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.; Yun, Hee Mann

    2000-01-01

    For the successful utilization of ceramic matrix composites (CMC) as hot-section components in advanced aeropropulsion engines, the CMC constituents will need to be tailored and optimized to meet all the critical property demands of each component. Under the High-Speed Research (HSR) and Advanced High-Temperature Engine Materials Technology (HITEMP) Programs, the NASA Glenn Research Center at Lewis Field initiated research to develop mechanistic models for key CMC thermostructural properties. These models would describe the effects of different constituent factors (composition, geometry, and volume fraction) and of potential application conditions (stress, time, temperature, and environment) on these properties. Particular focus was placed on both analytical and numerical modeling of state-of-the-art SiC/SiC composites where the primary load-bearing constituents are stoichiometric SiC fibers in a complex multiphase SiC matrix produced by chemical vapor infiltration and melt infiltration. Recent studies have resulted in computer-based numerical models for the elastic modulus, thermal expansion, and thermal conductivity properties of the SiC/SiC system. Additional studies have generated analytical and empirical models for the time dependence of composite rupture strength at temperatures above 2200 F (1200 C), where CMC's have an important thermostructural advantage over current nickel-based superalloys. These life models utilize thermal activation theory and fiber stress-rupture results measured at Glenn to generate Larson-Miller (L M) plots of fiber rupture strength versus q, a single time- and temperature-dependent parameter. Assuming a worse case in which the SiC matrix is cracked, rupture is then controlled by the time-dependent fracture characteristics of the fiber bundles bridging the matrix cracks. With this as the controlling mechanism, one can then use simple composite theory and the fiber L M plots to predict CMC rupture strength versus the q parameter. The dashed line shows the predicted rupture strength of a SiC/SiC composite that is reinforced by a state-of-the-art stoichiometric SiC fiber. For the q parameter, time is in hours and temperature in degrees kelvin. To generate these predictions, a two-dimensional 0 /90 composite with approximately 16 percent fiber in the applied stress direction and an air test environment were assumed. As such, it is possible to compare the model predictions against limited stress-rupture data for this CMC as shown by the data points. The good agreement confirms the rupture model at least for the selected CMC and test conditions. Thus for this particular SiC/SiC composite, one can estimate a 1000-hr rupture strength of approximately 12 ksi at 2400 F (T = 1588 K and q = 39 700 K). At lower CMC application stresses, the SiC matrix is typically uncracked, so both the fiber and matrix constituents share the composite load. In this case, CMC rupture is controlled by the constituent with the longest rupture time based on the creep rate of the composite. Measured Monkman-Grant plots of rupture time versus creep rate for the two SiC constituents have been used to develop CMC life models for this important application condition. NASA and DOD are currently using this information to establish application and material goals for more advanced CMC's that can be used at even higher temperatures.

  17. Distribution of Fullerene Nanoparticles between Water and Solid Supported Lipid Membranes: Thermodynamics and Effects of Membrane Composition on Distribution.

    PubMed

    Ha, Yeonjeong; Katz, Lynn E; Liljestrand, Howard M

    2015-12-15

    The distribution coefficient (Klipw) of fullerene between solid supported lipid membranes (SSLMs) and water was examined using different lipid membrane compositions. Klipw of fullerene was significantly higher with a cationic lipid membrane compared to that with a zwitterionic or anionic lipid membrane, potentially due to the strong interactions between negative fullerene dispersions and positive lipid head groups. The higher Klipw for fullerene distribution to ternary lipid mixture membranes was attributed to an increase in the interfacial surface area of the lipid membrane resulting from phase separation. These results imply that lipid composition can be a critical factor that affects bioconcentration of fullerene. Distribution of fullerene into zwitterionic unsaturated lipid membranes was dominated by the entropy contribution (ΔS) and the process was endothermic (ΔH > 0). This result contrasts the partitioning thermodynamics of highly and moderately hydrophobic chemicals indicating that the lipid-water distribution mechanism of fullerene may be different from that of molecular level chemicals. Potential mechanisms for the distribution of fullerene that may explain these differences include adsorption on the lipid membrane surfaces and partitioning into the center of lipid membranes (i.e., absorption). PMID:26569041

  18. Spatial distribution of total, ammonia-oxidizing, and denitrifying bacteria in biological wastewater treatment reactors for bioregenerative life support

    NASA Technical Reports Server (NTRS)

    Sakano, Yuko; Pickering, Karen D.; Strom, Peter F.; Kerkhof, Lee J.; Janes, H. W. (Principal Investigator)

    2002-01-01

    Bioregenerative life support systems may be necessary for long-term space missions due to the high cost of lifting supplies and equipment into orbit. In this study, we investigated two biological wastewater treatment reactors designed to recover potable water for a spacefaring crew being tested at Johnson Space Center. The experiment (Lunar-Mars Life Support Test Project-Phase III) consisted of four crew members confined in a test chamber for 91 days. In order to recycle all water during the experiment, an immobilized cell bioreactor (ICB) was employed for organic carbon removal and a trickling filter bioreactor (TFB) was utilized for ammonia removal, followed by physical-chemical treatment. In this study, the spatial distribution of various microorganisms within each bioreactor was analyzed by using biofilm samples taken from four locations in the ICB and three locations in the TFB. Three target genes were used for characterization of bacteria: the 16S rRNA gene for the total bacterial community, the ammonia monooxygenase (amoA) gene for ammonia-oxidizing bacteria, and the nitrous oxide reductase (nosZ) gene for denitrifying bacteria. A combination of terminal restriction fragment length polymorphism (T-RFLP), sequence, and phylogenetic analyses indicated that the microbial community composition in the ICB and the TFB consisted mainly of Proteobacteria, low-G+C gram-positive bacteria, and a Cytophaga-Flexibacter-Bacteroides group. Fifty-seven novel 16S rRNA genes, 8 novel amoA genes, and 12 new nosZ genes were identified in this study. Temporal shifts in the species composition of total bacteria in both the ICB and the TFB and ammonia-oxidizing and denitrifying bacteria in the TFB were also detected when the biofilms were compared with the inocula after 91 days. This result suggests that specific microbial populations were either brought in by the crew or enriched in the reactors during the course of operation.

  19. Gorillas are a host for Dientamoeba fragilis: an update on the life cycle and host distribution.

    PubMed

    Stark, Damien; Phillips, Owen; Peckett, Donna; Munro, Ursula; Marriott, Deborah; Harkness, John; Ellis, John

    2008-01-25

    Dientamoeba fragilis is a gastrointestinal protozoan that has a worldwide distribution and is emergeing as a common cause of diarrhea. As D. fragilis has a propensity to cause chronic illness with symptoms similar to irritable bowel syndrome (IBS) it is not surprising that some patients with D. fragilis are misdiagnosed as having IBS. In contrast to most other pathogenic protozoa very little is known about its life cycle, epidemiology and mode of transmission. What role animal reservoirs play in the transmission of this parasite is unknown. Consequently we undertook a prospective study to determine the host distribution of D. fragilis. Over a 2-year-period, 608 faecal samples from a wide range of animal and bird species, including pigs and other food species, were screened using permanent stained smears for the presence of D. fragilis. Trophozoites of D. fragilis were only detected in Western lowland gorillas (3/10) (Gorilla g. gorilla) and confirmed by PCR targeting the SSU rRNA gene. The limited host range detected suggests human infection may not involve transmission from other animal species. In addition, we provide an update on the limited knowledge about the life cycle of this parasite and its host distribution. PMID:18022187

  20. Determinants of Change in Stroke-Specific Quality of Life After Distributed Constraint-Induced Therapy

    PubMed Central

    Huang, Yan-Hua; Wu, Ching-Yi; Hsieh, Yu-Wei; Snow, Wilaiwan M.; Wang, Tien-Ni

    2013-01-01

    OBJECTIVE. We identified the predictive factors of change in quality of life (QOL) after a distributed form of constraint-induced therapy (dCIT) among stroke survivors. METHOD. Seventy-four participants were treated with dCIT. We identified eight potential determinants of change: age, gender, side of lesion, time since stroke, cognitive status, motor impairment of the upper extremity, activities of daily living (ADLs), and instrumental ADLs (IADLs). The Stroke-Specific Quality of Life Scale (SS–QOL) was used to assess QOL. RESULTS. Right-sided lesion and onset >17 mo earlier determined greater improvement in the SS–QOL Energy domain. Onset >10 mo earlier, poorer IADL performance, and age >68 yr predicted improvement in the Family Role, Mobility, and Mood domains, respectively. CONCLUSION. Side of lesion, time since stroke, IADL performance, and age were the most important determinants of QOL in patients receiving stroke motor rehabilitation. PMID:23245783

  1. Optimizing Powder Distribution in Production of Surface Nano-Composite via Friction Stir Processing

    NASA Astrophysics Data System (ADS)

    Heydarian, Arash; Dehghani, Kamran; Slamkish, Taymor

    2014-06-01

    Notwithstanding the extensive interest in using friction stir processing (FSP) for producing metal matrix composite (MMC), more uniform powder distribution along the composite zone is still needed. In most studies, one groove is machined out of the specimen, filled with powder, and then processed by identical passes. In this investigation, an innovative technique was used that involved machining out of three gradient grooves with increasing depth from the advancing side to the retreating side instead of using a conventional sample with just a groove. Macro, optical, and scanning electron microscopy (SEM) images and microhardness test were used to evaluate the powder distribution. The images indicated that the most uniform distribution of SiC particles in the whole composite zone was related to a three-gradient grooves sample. Microohardness measurement of a three-gradient grooves sample, carried out along the cross section and perpendicular to the traverse direction of FSP, experiences less fluctuation in hardness compared with other techniques.

  2. Development of Elderly Quality of Life Index – Eqoli: Item Reduction and Distribution into Dimensions

    PubMed Central

    Paschoal, Sérgio Márcio Pacheco; Filho, Wilson Jacob; Litvoc, Júlio

    2008-01-01

    OBJECTIVE To describe item reduction and its distribution into dimensions in the construction process of a quality of life evaluation instrument for the elderly. METHODS The sampling method was chosen by convenience through quotas, with selection of elderly subjects from four programs to achieve heterogeneity in the “health status”, “functional capacity”, “gender”, and “age” variables. The Clinical Impact Method was used, consisting of the spontaneous and elicited selection by the respondents of relevant items to the construct Quality of Life in Old Age from a previously elaborated item pool. The respondents rated each item’s importance using a 5-point Likert scale. The product of the proportion of elderly selecting the item as relevant (frequency) and the mean importance score they attributed to it (importance) represented the overall impact of that item in their quality of life (impact). The items were ordered according to their impact scores and the top 46 scoring items were grouped in dimensions by three experts. A review of the negative items was performed. RESULTS One hundred and ninety three people (122 women and 71 men) were interviewed. Experts distributed the 46 items into eight dimensions. Closely related items were grouped and dimensions not reaching the minimum expected number of items received additional items resulting in eight dimensions and 43 items. DISCUSSION The sample was heterogeneous and similar to what was expected. The dimensions and items demonstrated the multidimensionality of the construct. The Clinical Impact Method was appropriate to construct the instrument, which was named Elderly Quality of Life Index - EQoLI. An accuracy process will be examined in the future. PMID:18438571

  3. Nonparametric Fine Tuning of Mixtures: Application to Non-Life Insurance Claims Distribution Estimation

    NASA Astrophysics Data System (ADS)

    Sardet, Laure; Patilea, Valentin

    When pricing a specific insurance premium, actuary needs to evaluate the claims cost distribution for the warranty. Traditional actuarial methods use parametric specifications to model claims distribution, like lognormal, Weibull and Pareto laws. Mixtures of such distributions allow to improve the flexibility of the parametric approach and seem to be quite well-adapted to capture the skewness, the long tails as well as the unobserved heterogeneity among the claims. In this paper, instead of looking for a finely tuned mixture with many components, we choose a parsimonious mixture modeling, typically a two or three-component mixture. Next, we use the mixture cumulative distribution function (CDF) to transform data into the unit interval where we apply a beta-kernel smoothing procedure. A bandwidth rule adapted to our methodology is proposed. Finally, the beta-kernel density estimate is back-transformed to recover an estimate of the original claims density. The beta-kernel smoothing provides an automatic fine-tuning of the parsimonious mixture and thus avoids inference in more complex mixture models with many parameters. We investigate the empirical performance of the new method in the estimation of the quantiles with simulated nonnegative data and the quantiles of the individual claims distribution in a non-life insurance application.

  4. Waste prevention in liquid detergent distribution: a comparison based on life cycle assessment.

    PubMed

    Nessi, Simone; Rigamonti, Lucia; Grosso, Mario

    2014-11-15

    The distribution of liquid detergents through self-dispensing systems has been adopted in some Italian retail stores over the last few years. By enabling the consumer to refill several times the same container, it is proposed as a less waste-generating and more environmentally friendly alternative to the traditional distribution with single-use plastic containers. For this reason, its implementation is encouraged by the national waste prevention programme recently adopted in Italy. In order to assess such claims, a life cycle assessment was carried out to evaluate whether detergent distribution through self-dispensing systems actually allows to achieve the expected reduction in waste generation and environmental impacts. The focus was on the distribution within the large-scale retail trade and on the categories of laundry detergents, fabric softeners and hand dishwashing detergents. For each of them, a set of baseline single-use scenarios were compared with two alternative waste prevention scenarios, where the detergent is distributed through self-dispensing systems. Beyond waste generation, also the Cumulative Energy Demand and thirteen midpoint-level potential impact indicators were calculated for the comparison. Results showed that a reduction in waste generation up to 98% can be achieved, depending on the category of detergent, on the baseline scenario of comparison and on the number of times the refillable container is used. A progressive reduction in the energy demand and in most of the potential impacts was also observed, starting from a minimum number of uses of the refillable container. PMID:25209251

  5. End of life fission product distributions in F-1 experiment fuel rods

    SciTech Connect

    Goodin, D.T.; Langer, S.; Bell, W.E.

    1980-05-01

    Fission product migration and end-of-life distributions were examined in the F-1 (X094) series of sealed, mixed-oxide fuel rods irradiated in the fast flux of EBR-II. Cesium, rubidium, iodine, and strontium data obtained from axial gamma scanning, mass spectrometry, and radiochemical analyses are presented. The results show significant migration of cesium, probably as both a volatile species and as the noble gas precursor. Cesium metal species leaving the fuel region accumulate predominately at the fuel-blanket interface. Volatile cesium reaching the fission product traps is readily sorbed by the charcoal.

  6. Application of a Fiber Optic Distributed Strain Sensor System to Woven E-Glass Composite

    NASA Technical Reports Server (NTRS)

    Anastasi, Robert F.; Lopatin, Craig

    2001-01-01

    A distributed strain sensing system utilizing a series of identically written Bragg gratings along an optical fiber is examined for potential application to Composite Armored Vehicle health monitoring. A vacuum assisted resin transfer molding process was used to fabricate a woven fabric E-glass/composite panel with an embedded fiber optic strain sensor. Test samples machined from the panel were mechanically tested in 4-point bending. Experimental results are presented that show the mechanical strain from foil strain gages comparing well to optical strain from the embedded sensors. Also, it was found that the distributed strain along the sample length was consistent with the loading configuration.

  7. Simulations of Fiber Distribution Effects in Fiber-Reinforced Cement Composites

    SciTech Connect

    Bolander, John E.; Lim, Yun Mook

    2008-02-15

    This paper describes a lattice model for coupled moisture transport/stress analyses of fiber-reinforced cement composites (FRCC). Each fiber, and its interface with the matrix material, is explicitly represented within the three-dimensional material volume. This enables the direct study of fiber orientation and distribution effects on composite performance. Realistic, nonuniform fiber distributions can be specified as model input. Basic applications of the model are presented, with emphasis toward simulating the durability mechanics of FRCC exposed to drying environments. The modeling of functionally graded FRCC is an obvious potential extension of this work.

  8. Space Station Environmental Control and Life Support System architecture - Centralized versus distributed

    NASA Technical Reports Server (NTRS)

    Boehm, A. M.; Behrend, A. F.

    1984-01-01

    Both Centralized and Distributed approaches are being evaluated for the installation of Environmental Control and Life Support (ECLS) equipment in the Space Station. In the Centralized facility concept, integrated processing equipment is located in two modules with plumbing used to circulate ECLS services throughout the Station. The Distributed approach locates the ECLS subsystems in every module of the Space Station with each subsystem designed to meet its own module needs. This paper defines the two approaches and how the advantages and disadvantages of each are tied to the choice of Space Station architecture. Other considerations and evaluations include: crew movement, Station evolution and the ducting impact needed to circulate ECLS services from centrally located processing equipment.

  9. Multi-scale mechanism based life prediction of polymer matrix composites for high temperature airframe applications

    NASA Astrophysics Data System (ADS)

    Upadhyaya, Priyank

    A multi-scale mechanism-based life prediction model is developed for high-temperature polymer matrix composites (HTPMC) for high temperature airframe applications. In the first part of this dissertation the effect of Cloisite 20A (C20A) nano-clay compounding on the thermo-oxidative weight loss and the residual stresses due to thermal oxidation for a thermoset polymer bismaleimide (BMI) are investigated. A three-dimensional (3-D) micro-mechanics based finite element analysis (FEA) was conducted to investigate the residual stresses due to thermal oxidation using an in-house FEA code (NOVA-3D). In the second part of this dissertation, a novel numerical-experimental methodology is outlined to determine cohesive stress and damage evolution parameters for pristine as well as isothermally aged (in air) polymer matrix composites. A rate-dependent viscoelastic cohesive layer model was implemented in an in-house FEA code to simulate the delamination initiation and propagation in unidirectional polymer composites before and after aging. Double cantilever beam (DCB) experiments were conducted (at UT-Dallas) on both pristine and isothermally aged IM-7/BMI composite specimens to determine the model parameters. The J-Integral based approach was adapted to extract cohesive stresses near the crack tip. Once the damage parameters had been characterized, the test-bed FEA code employed a micromechanics based viscoelastic cohesive layer model to numerically simulate the DCB experiment. FEA simulation accurately captures the macro-scale behavior (load-displacement history) simultaneously with the micro-scale behavior (crack-growth history).

  10. Monitoring and service life estimation of reinforced concrete bridge decks rehabilitated with externally bonded carbon fiber reinforced polymer (CFRP) composites

    NASA Astrophysics Data System (ADS)

    Lee, Luke Soo-Won

    2005-11-01

    This dissertation develops methodologies to evaluate the integrity and effectiveness of external bonding of carbon fiber reinforced polymer (CFRP) composites to a reinforced concrete bridge deck. This document, while focused on bridge structures, develops techniques to have widespread application to other FRP rehabilitated structures. Wet lay-up and pultruded CFRP composites are applied to the deteriorated decks of the Watson Wash Bridge. A global vibration-based nondestructive evaluation procedure measuring changes in modal strain energy is used to determine stiffness changes in the bridge structure 1 month, 12 months, and 20 months after rehabilitation with CFRP composites. CFRP composite material variation and degradation are incorporated into a measure of the reliability index to estimate remaining service life. The reliability index also provides the means to combine the effects of material variation, CFRP composite degradation, and measured stiffness changes from the field to assess the service life of a FRP rehabilitated structure as shown from a series of progressive damage tests in the field. An approach for service life estimation is used to develop a service life based design methodology where the FRP rehabilitation design is determined based upon requirements of service life and an allowable reliability index.

  11. The particle size distribution function in the composite films and microwave magnetic properties

    NASA Astrophysics Data System (ADS)

    Kotov, L.; Ustyugov, V.; Vlasov, V.; Turkov, V.; Lasek, M.; Kalinin, Yu; Sitnikov, A.; Golubev, E.

    2016-04-01

    Nano- and microstructure of {(Co4-Fe4-Zr0.7)x+(A12O3)1-x} (Al series) and {(Co1-Nb0.2-Ta0.05)x+(SiO2)1-x} (A2 series) films was investigated by atomic force microscopy. The distributions of the metallic granules effective size by various concentrations of the metal phase were obtained. Microwave magnetic characteristics of composite films in respect of obtained distributions were calculated.

  12. Size and composition distribution of fine particulate matter emitted from wood burning, meat charbroiling, and cigarettes

    SciTech Connect

    Kleeman, M.J.; Schauer, J.J.; Cass, G.R.

    1999-10-15

    A dilution source sampling system is augmented to measure the size-distributed chemical composition of fine particle emissions from air pollution sources. Measurements are made using a laser optical particle counter (OPC), a differential mobility analyzer/condensation nucleus counter (DMA/CNC) combination, and a pair of microorifice uniform deposit impactors (MOUDIs). The sources tested with this system include wood smoke (pine, oak, eucalyptus), meat charbroiling, and cigarettes. The particle mass distributions from all wood smoke sources have a single mode that peaks at approximately 0.1--0.2 {micro}m particle diameter. The smoke from meat charbroiling shows a major peak in the particle mass distribution at 0.1--0.2 {micro}m particle diameter, with some material present at larger particle sizes. Particle mass distributions from cigarettes peak between 0.3 and 0.4 {micro}m particle diameter. Chemical composition analysis reveals that particles emitted from the sources tested here are largely composed of organic compounds. Noticeable concentrations of elemental carbon are found in the particles emitted from wood burning. The size distributions of the trace species emissions from these sources also are presented, including data for Na, K, Ti, Fe, Br, Ru, Cl, Al, Zn, Ba, Sr, V, Mn, Sb, La, Ce, as well as sulfate, nitrate, and ammonium ion when present in statistically significant amounts. These data are intended for use with air quality models that seek to predict the size distribution of the chemical composition of atmospheric fine particles.

  13. Thermal history, chemical composition and relationship of comets to the origin of life

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Leschine, S. B.; Schloerb, F. P.

    1980-01-01

    The role of thermal processes in determining the chemical composition of comets is considered, and implications of possible cometary constituents for the origin and evolution of life on earth are discussed. It is shown that the inclusion of short-lived Al-26 from a nearby supernova explosion into cometary nuclei could lead to comets with surfaces cool enough to retain H2O and interiors warm enough for thermal processing to occur, with the production of complex organic molecules such as amino acids and nucleic acid bases. It is thus suggested that comets may have played a part in seeding the primitive earth with biological polymers capable of self-replication or of evolving towards that capability, and may even be responsible for the subsequent introduction of organic material capable of infecting already existing cells.

  14. Receptor modelling of both particle composition and size distribution from a background site in London, UK

    NASA Astrophysics Data System (ADS)

    Beddows, D. C. S.; Harrison, R. M.; Green, D. C.; Fuller, G. W.

    2015-04-01

    Positive Matrix Factorisation (PMF) analysis was applied to PM10 chemical composition and particle Number Size Distribution (NSD) data measured at an urban background site (North Kensington) in London, UK for the whole of 2011 and 2012. The PMF analyses revealed six and four factors respectively which described seven sources or aerosol types. These included Nucleation, Traffic, Diffuse Urban, Secondary, Fuel Oil, Marine and Non-Exhaust/Crustal sources. Diffuse Urban, Secondary and Traffic sources were identified by both the chemical composition and particle number size distribution analysis, but a Nucleation source was identified only from the particle Number Size Distribution dataset. Analysis of the PM10 chemical composition dataset revealed Fuel Oil, Marine, Non-Exhaust Traffic/Crustal sources which were not identified from the number size distribution data. The two methods appear to be complementary, as the analysis of the PM10 chemical composition data is able to distinguish components contributing largely to particle mass whereas the number particle size distribution dataset is more effective for identifying components making an appreciable contribution to particle number. Analysis was also conducted on the combined chemical composition and number size distribution dataset revealing five factors representing Diffuse Urban, Nucleation, Secondary, Aged Marine and Traffic sources. However, the combined analysis appears not to offer any additional power to discriminate sources above that of the aggregate of the two separate PMF analyses. Day-of-the-week and month-of-the-year associations of the factors proved consistent with their assignment to source categories, and bivariate polar plots which examined the wind directional and wind speed association of the different factors also proved highly consistent with their inferred sources.

  15. Investigating low-frequency dielectric properties of a composite using the distribution of relaxation times technique

    SciTech Connect

    Tuncer, Enis; Bowler, Nicola; Youngs, I. J.; Lymer, K. P.

    2006-01-01

    The distribution of relaxation times approach, a less frequently employed dielectric data analysis technique, is utilized to better understand the relaxation characteristics of composites consisting of metal-coated, hollow glass spheres dispersed in a paraffin wax matrix. The dielectric properties of the composite samples are measured by means of impedance spectroscopy in the frequency range 0.1 mHz to 10 MHz. The application of a mixture law is not appropriate for the analysis of the frequency-dependent properties of the considered system on this broad frequency range. However, utilization of the distribution of relaxation times procedure to study the dielectric behaviour shows clear trends in the mixtures' relaxation spectra. Relaxation processes of the paraffin wax and those specific to the composites are found from the extracted distribution of relaxation times spectra. The influence of the filler concentration, q, on the dielectric properties is examined; a relaxation with a narrow distribution at intermediate frequencies becomes broad with the addition of the filler. This relaxation, in the form of the low-frequency-dispersions (also known as constant phase angle) phenomenon, dominates the dielectric properties of the composites with high bead concentration, q>0.15. The variation in dielectric properties of individual samples whose bead concentrations q are nominally the same is discussed in terms of possible microstructural variations.

  16. Investigating low frequency dielectric properties of a composite using the distribution of relaxation times technique

    SciTech Connect

    Tuncer, Enis

    2006-01-01

    The distribution of relaxation times approach, a less frequently employed dielectric data analysis technique, is utilized to better understand the relaxation characteristics of composites consisting of metal-coated, hollow glass spheres dispersed in a paraffin wax matrix. The dielectric properties of the composite samples are measured by means of impedance spectroscopy in the frequency range 0.1mHz to 10 MHz. The application of a mixture law is not appropriate for the analysis of the frequency-dependent properties of the considered system on this broad frequency range. However, utilization of the distribution of relaxation times procedure to study the dielectric behaviour shows clear trends in the mixtures' relaxation spectra. Relaxation processes of the paraffin wax and those specific to the composites are found from the extracted distribution of relaxation times spectra. The influence of the filler concentration, q, on the dielectric properties is examined; a relaxation with a narrow distribution at intermediate frequencies becomes broad with the addition of the filler. This relaxation, in the form of the low-frequency-dispersions (also known as constant phase angle) phenomenon, dominates the dielectric properties of the composites with high bead concentration, q > 0:15. The variation in dielectric properties of individual samples whose bead concentrations q are nominally the same is discussed in terms of possible microstructural variations.

  17. The effects of chemical composition and distribution on the preservation of phytolith morphology

    NASA Astrophysics Data System (ADS)

    Wu, Yan; Yang, Yimin; Wang, Hua; Wang, Changsui

    2014-02-01

    Different types of phytolith even when coming from the same plant react to high temperatures in different ways. To understand the behavior of phytoliths upon heating, we examined composition and distribution of some elements within different phytolith types using SEM-EDS and synchrotron radiation μ-X-ray fluorescence. By analyzing phytoliths from rice husk, rice leaf and Than tree leaf, we find that the compositions and distributions of metal oxides within different phytolith types are quite different. It is well known that metal oxides have been used as fluxing agent to reduce the melting temperature of SiO2 in the production of glass, and different metal oxides can be used to produce a variety of glass with diverse features. Similarly, metal elements including potassium, magnesium and calcium in phytoliths should also act as a fluxing agent under high temperature, and the differential compositions and distributions of these metal elements within the phytoliths resulted in the variable reaction to heating. In sum, there is a negative relationship between the flux elements composition in phytoliths, and the temperatures at which phytoliths deform; furthermore, potassium and calcium in the rice leaf phytolith are almost evenly distributed in all parts, which may cause the phytolith's shape to deform evenly. In comparison, Than tree leaf phytolith is found to have a high percentage of potassium and calcium located exclusively on the outside, which may explain why the deformation of Than tree leaf phytolith occurs firstly at the outside.

  18. DISTRIBUTION OF PROTEIN COMPOSITION IN BREAD WHEAT FLOUR MILL STREAMS AND RELATIONSHIP TO BREADMAKING QUALITY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat protein quantity and composition are important parameters for wheat baking quality. The objective of this study was to use fractionation techniques to separate the proteins of flour mill streams into various protein fractions, to examine the distribution of these protein fractions, and to esta...

  19. Bumble bees (Hymenoptera: Apidae: Bombus spp.) of interior Alaska: Species composition, distribution, seasonal biology, and parasites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite the ecological and agricultural significance of bumble bees in Alaska, very little is known and published about this important group at the regional level. The objectives of this study were to provide baseline data on species composition, distribution, seasonal biology, and parasites of the ...

  20. Detecting composition and monomer sequence distribution in random copolymers with interaction chromatography

    NASA Astrophysics Data System (ADS)

    Han, Junwon; Ryu, Chang Y.; Semler, James J.; Genzer, Jan

    2006-03-01

    We demonstrate that interaction chromatography (IC) is capable of discriminating among both the chemical composition and monomer sequence distribution in random copolymers. By fine-tuning the separation conditions in the IC (solvent type and stationary phase type), we were able to delineate the effect of both their chemical composition and the monomer sequence distribution of partially brominated polystyrenes on chromatographic retention. The degree of bromination and the 4-BrS sequencing was controlled by varying the bromine concentration in the reaction vessel, bromination reaction time, and solvent temperature. Our experiments suggest that 1) the blockiness of 4-BrS adsorption segments can further enhance the surface affinity of the copolymer chains at a fixed copolymer chemical composition, and 2) the adsorption-based molecular recognition of copolymer chains occurs by cooperative and synergistic adsorption of segments on surfaces along with neighboring adsorptive segments.

  1. Hydrogen isotopic compositions of n-alkanes from terrestrial plants correlate with their ecological life forms.

    PubMed

    Liu, Weiguo; Yang, Hong; Li, Liwu

    2006-11-01

    Stable hydrogen isotopic compositions (deltaD) of compound-specific biomarkers, such as n-alkanes from plant leaf waxes, can be used as a proxy for paleoclimatic change. However, the relationship between hydrogen isotopes of plant leaf wax and plant ecological life forms is not well understood. Here, we report the deltaD of n-alkanes from 34 modern terrestrial plants, including twenty-one C(3) plants and thirteen C(4) plants from northwestern China, determined using gas chromatography/thermal conversion/isotope ratio mass spectrometry. Our data show that the stable hydrogen isotopes are poorly correlated with the plant photosynthetic pathway (C(3) vs. C(4)) and that they do not give clear regional precipitation signals. Together with a comparative analysis of published deltaD values from plant leaf waxes in other regions, we believe that the stable hydrogen isotope of plant leaf waxes is more closely related to ecological life forms of these terrestrial plants (i.e. tree, shrub, and grass). In general, the grasses have more negative deltaD values than the co-occurring trees and shrubs. Our findings suggest that the deltaD values of sedimentary leaf waxes from higher plants may record changes of a plant ecosystem under the influence of environmental alteration and imply that reconstruction of the paleoclimate using deltaD values from plant n-alkanes should be based upon specific plant taxa, and comparison should be made among plants with similar ecological life forms. PMID:16977462

  2. Fatigue-life behavior and matrix fatigue crack spacing in unnotched SCS-6/Timetal 21S metal matrix composites

    NASA Technical Reports Server (NTRS)

    Ward, G. T.; Herrmann, D. J.; Hillberry, B. M.

    1993-01-01

    Fatigue tests of the SCS-6/Timetal 21S composite system were performed to characterize the fatigue behavior for unnotched conditions. The stress-life behavior of the unnotched (9/90)2s laminates was investigated for stress ratios of R = 0.1 and R = 0.3. The occurrence of matrix cracking was also examined in these specimens. This revealed multiple matrix crack initiation sites throughout the composite, as well as evenly spaced surface cracks along the length of the specimens. No difference in fatigue lives were observed for stress ratios of R = 0.1 and R = 0.3 when compared on a stress range basis. The unnotched SCS-6/Timetal 21S composites had shorter fatigue lives than the SCS-6/Ti-15-3 composites, however the neat Timetal 21S matrix material had a longer fatigue life than the neat Ti-15-3.

  3. Controls on the distribution and isotopic composition of helium in deep ground-water flows

    USGS Publications Warehouse

    Zhao, X.; Fritzel, T.L.B.; Quinodoz, H.A.M.; Bethke, C.M.; Torgersen, T.

    1998-01-01

    The distribution and isotopic composition of helium in sedimentary basins can be used to interpret the ages of very old ground waters. The piston-flow model commonly used in such interpretation, how ever, does not account for several important factors and as such works well only in very simple flow regimes. In this study of helium transport in a hypothetical sedimentary basin, we develop a numerical model that accounts for the magnitude and distribution of the basal helium flux, hydrodynamic dispersion, and complexities in flow regimes such as subregional flow cells. The modeling shows that these factors exert strong controls on the helium distribution and isotopic composition. The simulations may provide a basis for more accurate interpretations of observed helium concentrations and isotopic ratios in sedimentary basins.

  4. Simulation and quantitative assessment of homogeneous and inhomogeneous particle distributions in particulate metal matrix composites.

    PubMed

    Yang, N.; Boselli, J.; Sinclair, I.

    2001-02-01

    Reinforcement distributions play an important role in various aspects of the processing and final mechanical behaviour of particulate metal matrix composites (PMMCs). Methods for quantifying spatial distribution in such materials are, however, poorly developed, particularly in relation to the range of particle size, shape and orientation that may be present in any one system. The present work investigates via computer simulations the influences of particle morphology, homogeneity and inhomogeneity on spatial distribution measurements obtained by finite-body tessellation. Distribution inhomogeneity was simulated both by the segregation of particles away from specified regions within a microstructure and by generating point density peaks at random locations within a microstructure. Both isotropic and anisotropic inhomogeneous distributions were considered to simulate distribution patterns in PMMCs before and after mechanical working. It was found that the coefficient of variation of the mean near-neighbour distance (COV(dmean)), derived from particle interfaces using finite-body tessellation, was essentially independent of particle shape, size distribution, orientation and area fraction in homogeneous (random) distributions, but showed great sensitivity to inhomogeneity. Increased values of COV(dmean) were seen for both forms of inhomogeneous distributions considered here, with little influence of particle morphology. The COV(dmean) was also seen to be sensitive to anisotropic clustering, the presence of which was identified via nearest-neighbour angles and cell orientations. Although generally formulated for PMMCs, the present results may be generalized to other systems containing low aspect ratio finite bodies of low to moderate area fraction. PMID:11207921

  5. Frequency Distributions of Geochemical Data, Scaling Laws, and Properties of Compositions

    NASA Astrophysics Data System (ADS)

    Buccianti, Antonella

    2015-07-01

    Many random processes occur in geochemistry. Accurate predictions of the manner in which elements or chemical species interact with each other are needed to construct models able to treat the presence of random components. Although modelling of frequency distributions with some probabilistic models (for example Gaussian, log-normal, Pareto) has been well discussed in several fields of application, little attention has been devoted to the features of compositional data and, in particular, to their multivariate nature. In this contribution an approach coherent with the properties of compositional information is proposed and used to investigate the shape of the frequency distribution of geochemical indices obtained by robust multivariate analysis. The purpose is to understand data-generation processes from the perspective of compositional theory. The approach is based on use of transformations of the log-ratio family, each with peculiar theoretical and practical advantages, depending on the statistical methods adopted. Accordingly, because, in compositional data, all the relevant information about one term ( x i ) of a D-part composition is contained in the ratios to each of the remaining parts x 2,…, x D , analysis of single variables is abandoned. The proposed methodology directs attention to modelling of the frequency distribution of more complex indices, linking all the terms of the composition to better represent the dynamics of geochemical processes. An example of its application is presented and discussed on the basis of consideration of the chemistry of 616 ocean floor basaltic (OFB) glasses from the abyssal volcanic glass data file (AVGDF) of the Smithsonian Institution.

  6. Major elements composition, Li distribution and isotopic composition in peridotite xenoliths from Allegre and Mont Coupet (French Massif Central)

    NASA Astrophysics Data System (ADS)

    Xiaoyan, Gu; Etienne, Deloule; Lyderic, France; Jannick, Ingrin

    2014-05-01

    The peridotite xenoliths from two localities (the Ringue quarry in Allegre; Mont Coupet) belong to the Massif Central southern domain, which have been accredited as a circumcratonic segment and been rejuvenated during the Variscan orogeny (Lenoir et al. 2000). The Ringue quarry is opened in a lava lake and, in contrast, Mont Coupet is a strombolian eruptive volcano. Major element compositions, Li distribution and isotope compositions in minerals from these xenoliths were measured to describe the evolution of the sub-continental lithospheric mantle, and to look for Li exchange during the melt-rock interaction. As for major element compositions, the samples from two localities fall into the off-craton field (Rudnick et al., 2004) and the compositional ranges of the southern domain of the French Massif Central (Downes et al., 2003). They have also been imprinted by mantle metasomatism, which engendered much higher Mg# of cpx (up to 93.5) relative to their co-existing olivines (89.2 to 91.5). In the Allegre samples, large variations between the equilibration temperatures of mineral cores and rims indicate disequilibrium resulting from mantle metasomatism. Cpx display enriched Li contents (up to 24 ppm) and Li partitioning between cpx and olivine/opx strongly deviates from the equilibrated trend (Seitz and Woodland, 2000), suggestive of their interaction with mafic silicate melts and/or fluids with high Li contents. The highly negative ?7Li values (down to -25o ) compared to the primary mantle value of 42o (Rudnick and Ionov, 2007) and the large inter-mineral Li isotope fractionations attest for Li exchange with melts and/or fluids during metasomatic events. Mont Coupet samples display equilibrated Li distribution and isotopic composition at the thin section scale, but an inverse relationship between the Li contents and Li isotope compositions between the different samples, indicating a large-scale Li diffusion process, occurring before the xenoliths exhumation. In conclusion, the different types of host magmas should be a significant factor that leads to these extremely diverse characteristics of Li distribution and isotope compositions in the samples from Allegre and Mont Coupet. In the lava lake, host magmas have kept relatively long-term high temperatures and this provided time for Li to diffuse from infiltrated metasomatic melts or host magmas. On the contrary, Mont Coupet has cooled rapidly and the xenoliths could preserve the geochemical state of Li in the mantle depth. Lenoir et al, 2000, Earth Planet. Sci. Lett. 181, 359- 375. Rudnick et al., 2004, Lithos 77, 609-637. Downes et al., 2003, Chem. Geol. 200, 71-87. Seitz and Woodland, 2000, Chem. Geol. 166, 47-64. Rudnick and Ionov, 2007, Earth Planet. Sci. Lett. 256, 278-293.

  7. A creep cavity growth model for creep-fatigue life prediction of a unidirectional W/Cu composite

    NASA Technical Reports Server (NTRS)

    Kim, Young-Suk; Verrilli, Michael J.; Halford, Gary R.

    1992-01-01

    A microstructural model was developed to predict creep-fatigue life in a (0)(sub 4), 9 volume percent tungsten fiber-reinforced copper matrix composite at the temperature of 833 K. The mechanism of failure of the composite is assumed to be governed by the growth of quasi-equilibrium cavities in the copper matrix of the composite, based on the microscopically observed failure mechanisms. The methodology uses a cavity growth model developed for prediction of creep fracture. Instantaneous values of strain rate and stress in the copper matrix during fatigue cycles were calculated and incorporated in the model to predict cyclic life. The stress in the copper matrix was determined by use of a simple two-bar model for the fiber and matrix during cyclic loading. The model successfully predicted the composite creep-fatigue life under tension-tension cyclic loading through the use of this instantaneous matrix stress level. Inclusion of additional mechanisms such as cavity nucleation, grain boundary sliding, and the effect of fibers on matrix-stress level would result in more generalized predictions of creep-fatigue life.

  8. Nutrient composition and respiration characteristics of silkworms in the Bioregenerative Life Support System

    NASA Astrophysics Data System (ADS)

    Tong, Ling; Yu, Xiaohui; Liu, Hong

    As the appropriate space animal candidate, silkworm(Bombyx Mori L.) can supply animal food for taikonauts and consume inedible parts of plants in Bioregenerative Life Support Sys-tem(BLSS). Due to the features of BLSS, the silkworm breeding method in the system differ-ent from the conventional one is feeding the silkworm in the first three developing stages with mulberry leaves and with lettuce leaves in the latter two developing stages. Therefore, it is nec-essary to investigate the biochemical components and respiration characteristics of silkworms raised with this method to supply data bases for the inclusion of silkworms in the system to conduct system experiments. The nutrient compositions of silkworm powder (SP) which are the grinded and freeze-dried silkworm on the 3rd day in the fifth developing stage containing protein, fat, vitamins, minerals and fatty acids were determined with international standard analyzing methods in this study. The results showed that SP was rich in protein and amino acids. There were twelve kinds of essential vitamins, nine kinds of minerals and twelve kinds of fatty acids in SP. In contrast, SP had much better nutrient components than snail, fish, chicken, beef and pork as animal food for crew members. Moreover, 359 kCal can be generated per 100g of SP (dry weight). The respirations of silkworm during its whole growing process under two main physiological statuses which were eating and non-eating leaves were studied. According to the results measured by the animal respiration measuring system, there were much difference among the respirations of silkworms under the two main physiological statuses. The amounts of O2 inhaled and CO2 exhaled by the silkworms when they were eating leaves were more than those under the non-eating status. Even under the same status, the respiration characteristics of silkworms in five different developing stages were also different from one an-other. The respiratory quotients of silkworms under two statuses are largely different (eating F=3.191, P<0.05; non-eating F=2.935, P <0.05). Moreover, the amounts of O2 inhaled and CO2 exhaled by the silkworms in the first three developing stages were much more than those of the silkworms in the latter two developing stages per unit weight of leaves. These results concerning the nutrient compositions and respiration characteristics of silkworms can provide valuable data for the establishment of complex bioregenerative life support systems including different biological units in the lunar or mars bases in the future.

  9. Aerobic training during hemodialysis improves body composition, muscle function, physical performance, and quality of life in chronic kidney disease patients

    PubMed Central

    Bae, Young-Hyeon; Lee, Suk Min; Jo, Jong Il

    2015-01-01

    [Purpose] We assessed the influences of individualized aerobic training on body composition, knee joint muscle function, physical performance, and quality of life in chronic kidney disease patients. [Subjects] Ten chronic kidney disease patients undergoing dialysis. [Methods] Overall physical function and quality of life before and after 12 weeks of aerobic training were evaluated by body composition, the six-minute walk test, cardiopulmonary exercise tests, and Short Form 36-item questionnaire. [Results] The six-minute walk test distance increased significantly after 12 weeks aerobic training. Resting metabolic rate, lactate threshold, maximum oxygen uptake, and quality of life tended to increase after training. Post-training weight, muscle mass, body fat mass, fat percentage, body mass index, and peak torque of right and left knee extension and flexion did not change significantly. [Conclusion] Intra-dialytic training can a safe approach to maintain or improve physical performance and quality of life of chronic kidney disease patients undergoing hemodialysis without adverse events or negative cardiovascular responses. Aerobic training may prevent a decline in body composition and knee joint muscle function due to inactivity in chronic kidney disease patients. Clinically, aerobic training may initially be adapted to maintain overall physical function or improve quality of life in chronic kidney disease patients undergoing hemodialysis. PMID:26157237

  10. Determing Lamprey Species Composition, Larval Distribution, and Adult Abundance in the Deschutes River, Oregon, Subbasin; 2005-2006 Annual Report.

    SciTech Connect

    Graham, Jennifer C.; Brun, Christopher V.

    2006-05-01

    Information about lamprey species composition, distribution, life history, abundance, habitat requirements, and exploitation in the lower Deschutes River Subbasin is extremely limited. During 2002, we began a multi-year study to assess the status of lamprey in the Deschutes River subbasin. The objectives of this project are to determine ammocoete (larval lamprey) distribution and associated habitats; Lampretra species composition; numbers of emigrants; adult escapement and harvest rates at Sherars Falls. This report describes the preliminary results of data collected during 2005. We continued documenting ammocoete (larval) habitat selection by surveying four perennial eastside tributaries to the Deschutes River (Warm Springs River, Badger, Beaver and Shitike creeks) within the known ammocoete distribution. The results of 2003-2005 sampling indicate that positive relationships exist between: presence of wood (P = < 0.001), depositional area (P = < 0.001), flow (P = < 0.001), and fine substrate (P = < 0.001). Out-migrants numbers were not estimated during 2005 due to our inability to recapture marked larvae. In Shitike Creek, ammocoete and microphthalmia out-migration peaked during November 2005. In the Warm Spring River, out-migration peaked for ammocoetes in April 2006 and December 2005 for microphthalmia. Samples of ammocoetes from each stream were retained in a permanent collection of future analysis. An escapement estimate was generated for adult Pacific lamprey in the lower Deschutes River using a two event mark-recapture experiment during run year 2005. A modified Peterson model was used to estimate the adult population of Pacific lamprey at 3,895 with an estimated escapement of 2,881 during 2005 (95% CI= 2,847; M = 143; C = 1,027 R = 37). A tribal creel was also conducted from mid-June through August. We estimated tribal harvest to be approximately 1,015 adult lamprey during 2005 (95% CI= +/- 74).

  11. Recycling and reuse of waste from electricity distribution networks as reinforcement agents in polymeric composites.

    PubMed

    Zimmermann, Matheus V G; Zattera, Ademir J

    2013-07-01

    Of the waste generated from electricity distribution networks, wooden posts treated with chromated copper arsenate (CCA) and ceramic insulators make up the majority of the materials for which no effective recycling scheme has been developed. This study aims to recycle and reuse this waste as reinforcement elements in polymer composites and hybrid composites, promoting an ecologically and economically viable alternative for the disposal of this waste. The CCA wooden posts were cut, crushed and recycled via acid leaching using 0.2 and 0.4N H2SO4 in triplicate at 70°C and then washed and dried. The ceramic insulators were fragmented in a hydraulic press and separated by particle size using a vibrating sieve. The composites were mixed in a twin-screw extruder and injected into the test specimens, which were subjected to physical, mechanical, thermal and morphological characterization. The results indicate that the acid treatment most effective for removing heavy metals in the wood utilizes 0.4NH2SO4. However, the composites made from wood treated with 0.2NH2SO4 exhibited the highest mechanical properties of the composites, whereas the use of a ceramic insulator produces composites with better thermal stability and impact strength. This study is part of the research and development project of ANEEL (Agência Nacional de Energia Elétrica) and funded by CPFL (Companhia Paulista de Força e Luz). PMID:23663959

  12. Fatigue Life Prediction of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures. Part II: Experimental Comparisons

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    This paper follows on from the earlier study (Part I) which investigated the fatigue behavior of unidirectional, cross-ply and 2.5D C/SiC composites at room and elevated temperatures. In this paper, a micromechanics approach to predict the fatigue life S-N curves of fiber-reinforced CMCs has been developed considering the fatigue damage mechanism of interface wear or interface oxidation. Upon first loading to fatigue peak stress, matrix multicracking and fiber/matrix interface debonding occur. The two-parameter Weibull model is used to describe fibers strength distribution. The stress carried by broken and intact fibres on the matrix crack plane under fatigue loading is determined based on the Global Load Sharing (GLS) criterion. The fibres failure probabilities under fatigue loading considering the degradation of interface shear stress and fibres strength have been obtained. When the broken fibres fraction approaches critical value, the composite would fatigue fail. The fatigue life S-N curves of unidirectional, cross-ply and 2.5D C/SiC composites at room and elevated temperatures have been predicted. The predicted results agreed with experimental data.

  13. Distribution and compositional change of organic materials with the evolution or a protoplanetary disk

    NASA Astrophysics Data System (ADS)

    Nagahara, Hiroko

    2015-08-01

    A protoplanetary disk evolves dynamically, which changes the physical and chemical conditions temporally and spatially. Evolution of organic materials derived from the previous molecular cloud has been extensively studied by chemical network calculation assuming chemical reaction on the surface of grains. Such surface reaction would have played important roles at the very early stage of disk evolution or low temperature outer region; however, thermal processes should have been the dominant reaction at later or high temperature (~above the melting point of water ice) regions. Those organics should have been incorporated into planetesimals that would be a precursor material of life.We have developed a protoplanetary disk evolution model by combining fluid dynamics and chemical change of organics with the molecular cloud origin. On the basis of calculation, we discuss the temporal and spatial change of organics within the inner region of the disk. The organics initially has a composition of cometary organics, which is assume not to change up to T~250K, becomes rich in C up to T~400K, and changed into almost pure C at T>500K. At the early stage of disk evolution (t<105 years), a significant fraction of refractory organics (enriched in C and depleted in H, O, and N) is present in the asteroid belt, and the primitive (max T< 250K) organics are distributed beyond several AU, whereas, the primitive organics reached at the inner edge of the asteroid belt. Primitive organics are not present at ~1AU through the disk evolution.The results strongly suggests that the Earth does not contain primitive organics if all the embryos that formed the Earth were derived within ~2AU. On the other hand, some fraction of organics in the asteroid belt would be primitive that retain primitive nature originated in the molecular cloud with heavy isotope enrichments. If the disk was heavy and the high temperature region extended to outer regions, organics supplied to the steroidal belt should be thermally processed and depleted in H, O, and N compared to cometary organics.

  14. Phospholipid and triacylglycerol fatty acid composition of major life stages of sunn pest, Eurygaster integriceps (Heteroptera: Scutelleridae).

    PubMed

    Bashan, Mehmet; Akbas, Halit; Yurdakoc, Kadir

    2002-06-01

    Phospholipid and triacylglycerol fatty acid compositions of whole animals from all life stages of Eurygaster integriceps, including eggs, nymphs, pre-diapausing adults and diapausing adults, were determined. The fatty acid composition of total lipids of their food, wheat, was also determined. The major components of the insects and their food were the expected C16 and C18 saturated and unsaturated fatty acids. Since fatty acid compositions of third-stadium nymphs were not similar to the profiles of their food, most likely, dietary fatty acids are modified by the insect. The fact is that the food does not provide C20 polyunsaturated fatty acids, but the insect tissue lipids include these components. We suggest biosynthesis of the C20 components by elongation/desaturation of C18:2n-6, an abundant component of the diets. We also show differences in fatty acid profiles from each of the life stages. PMID:12031463

  15. X7R Lead-Complex Perovskite Dielectrics with Inhomogeneous Compositional Distribution

    NASA Astrophysics Data System (ADS)

    Uchikoba, Fumio; Ito, Takashi; Nakajima, Shigeyuki

    1995-05-01

    Excess- WO3 Pb(Mg1/2W1/2)O3-PbTiO3-Pb(Ni2/3Nb2/3)O3 polycrystalline dielectric material was investigated. This material met EIA X7R specifications (the change of the capacitance is less than 15% over the temperature range from -55° C to +125° C). The material showed inhomogeneous compositional distributions within grains that consisted of three main parts, each possessing a different temperature dependence of the dielectric constant. It was found that the flat-temperature dependence of the dielectric constant in this system could be attributed to this inhomogeneous compositional distribution. Using this material, multilayer ceramic capacitors were fabricated.

  16. Deep ultraviolet distributed Bragg reflectors based on graded composition AlGaN alloys

    SciTech Connect

    Brummer, Gordie; Nothern, Denis; Nikiforov, A. Yu.; Moustakas, T. D.

    2015-06-01

    Distributed Bragg reflectors (DBRs) with peak reflectivity at approximately 280 nm, based on compositionally graded Al{sub x}Ga{sub 1−x}N alloys, were grown on 6H-SiC substrates by plasma-assisted molecular beam epitaxy. DBRs with square, sinusoidal, triangular, and sawtooth composition profiles were designed with the transfer matrix method. The crystal structure of these DBRs was studied with high-resolution x-ray diffraction of the (1{sup ¯}015) reciprocal lattice point. The periodicity of the DBR profiles was confirmed with cross-sectional Z-contrast scanning transmission electron microscopy. The peak reflectance of these DBRs with 15.5 periods varies from 77% to 56% with corresponding full width at half maximum of 17–14 nm. Coupled mode analysis was used to explain the dependence of the reflectivity characteristics on the profile of the graded composition.

  17. Loading Analysis of Composite Wind Turbine Blade for Fatigue Life Prediction of Adhesively Bonded Root Joint

    NASA Astrophysics Data System (ADS)

    Salimi-Majd, Davood; Azimzadeh, Vahid; Mohammadi, Bijan

    2015-06-01

    Nowadays wind energy is widely used as a non-polluting cost-effective renewable energy resource. During the lifetime of a composite wind turbine which is about 20 years, the rotor blades are subjected to different cyclic loads such as aerodynamics, centrifugal and gravitational forces. These loading conditions, cause to fatigue failure of the blade at the adhesively bonded root joint, where the highest bending moments will occur and consequently, is the most critical zone of the blade. So it is important to estimate the fatigue life of the root joint. The cohesive zone model is one of the best methods for prediction of initiation and propagation of debonding at the root joint. The advantage of this method is the possibility of modeling the debonding without any requirement to the remeshing. However in order to use this approach, it is necessary to analyze the cyclic loading condition at the root joint. For this purpose after implementing a cohesive interface element in the Ansys finite element software, one blade of a horizontal axis wind turbine with 46 m rotor diameter was modelled in full scale. Then after applying loads on the blade under different condition of the blade in a full rotation, the critical condition of the blade is obtained based on the delamination index and also the load ratio on the root joint in fatigue cycles is calculated. These data are the inputs for fatigue damage growth analysis of the root joint by using CZM approach that will be investigated in future work.

  18. A Comparison of Various Stress Rupture Life Models for Orbiter Composite Pressure Vessels and Confidence Intervals

    NASA Technical Reports Server (NTRS)

    Grimes-Ledesma, Lorie; Murthy, Pappu L. N.; Phoenix, S. Leigh; Glaser, Ronald

    2007-01-01

    In conjunction with a recent NASA Engineering and Safety Center (NESC) investigation of flight worthiness of Kevlar Overwrapped Composite Pressure Vessels (COPVs) on board the Orbiter, two stress rupture life prediction models were proposed independently by Phoenix and by Glaser. In this paper, the use of these models to determine the system reliability of 24 COPVs currently in service on board the Orbiter is discussed. The models are briefly described, compared to each other, and model parameters and parameter uncertainties are also reviewed to understand confidence in reliability estimation as well as the sensitivities of these parameters in influencing overall predicted reliability levels. Differences and similarities in the various models will be compared via stress rupture reliability curves (stress ratio vs. lifetime plots). Also outlined will be the differences in the underlying model premises, and predictive outcomes. Sources of error and sensitivities in the models will be examined and discussed based on sensitivity analysis and confidence interval determination. Confidence interval results and their implications will be discussed for the models by Phoenix and Glaser.

  19. Life Limiting Behavior in Interlaminar Shear of Continuous Fiber-Reinforced Ceramic Matrix Composites at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Calomino, Anthony M.; Bansal, Narottam P.; Verrilli, Michael J.

    2006-01-01

    Interlaminar shear strength of four different fiber-reinforced ceramic matrix composites was determined with doublenotch shear test specimens as a function of test rate at elevated temperatures ranging from 1100 to 1316 C in air. Life limiting behavior, represented as interlaminar shear strength degradation with decreasing test rate, was significant for 2-D crossplied SiC/MAS-5 and 2-D plain-woven C/SiC composites, but insignificant for 2-D plain-woven SiC/SiC and 2-D woven Sylramic (Dow Corning, Midland, Michigan) SiC/SiC composites. A phenomenological, power-law delayed failure model was proposed to account for and to quantify the rate dependency of interlaminar shear strength of the composites. Additional stress rupture testing in interlaminar shear was conducted at elevated temperatures to validate the proposed model. The model was in good agreement with SiC/MAS-5 and C/SiC composites, but in poor to reasonable agreement with Sylramic SiC/SiC. Constant shear stress-rate testing was proposed as a possible means of life prediction testing methodology for ceramic matrix composites subjected to interlaminar shear at elevated temperatures when short lifetimes are expected.

  20. Determing Lamprey Species Composition, Larval Distribution, and Adult Abundance in the Deschutes River, Oregon, Subbasin; 2001-2002 Annual Report.

    SciTech Connect

    Graham, Jennifer C.; Brun, Christopher V.

    2003-05-01

    Information about lamprey species composition, distribution, life history, abundance, habitat requirements and exploitation in lower Deschutes River tributaries is extremely limited. To assess the status of lampreys in the Deschutes River subbasin, baseline information is needed. We operated to rotary screw traps in the Warm Springs River and Shitike Creek to gain an understanding of species composition, migration time and production. We identified Pacific lampreys in two life stages, ammocoete and macropthalmia. It appears that Pacific lamprey macropthalmia out-migrate during winter in the Warm Springs River. We saw peak movements by ammocoetes in the spring in Shitike Creek and winter in the Warm Springs River. We found no relationship between stream discharge and the number of lamprey collected. Very few macropthalmia were collected in Shitike Creek. Ammocoete size in the Warm Springs River and Shitike Creek were different. The ammocoetes in the Shitike Creek trap were close in size to the macropthalmia collected in the Warm Springs River trap. We also completed planning and preparation for larval and associated habitat data collection. This preparation included purchasing necessary field equipment, selecting and marking sampling areas and attending training with US Fish and Wildlife Service (USFWS) and the Confederated Tribes of Umatilla Indian Reservation (CTUIR). Because lamprey identification is difficult we met with US Geological Survey (USGS) to assist us with larval lamprey identification techniques. We have also been working in coordination with the Oregon Department of Fish and Wildlife (ODFW) to prepare and implement creel surveys and a mark-recapture study at Sherar's Falls to estimate adult lamprey escapement.

  1. Habitat and distribution of post-recruit life stages of the squid Loligo forbesii

    NASA Astrophysics Data System (ADS)

    Smith, Jennifer M.; Macleod, Colin D.; Valavanis, Vasilis; Hastie, Lee; Valinassab, Tooraj; Bailey, Nick; Santos, M. Begoña; Pierce, Graham J.

    2013-10-01

    This study models habitat preferences of the squid Loligo forbesii through its post-recruitment life cycle in waters around Scotland (UK). Trawl survey and market sample data from 1985 to 2004 are used to model seasonal habitats of immature, maturing and mature squid (maturity being inferred from size and season). Squid presence-absence and catch rate in areas of presence were analysed using generalised additive models, relating spatiotemporal patterns of distribution and abundance to ecogeographic variables. For all maturity classes, higher abundance in winter and spring (i.e., quarters 1 and 2) was associated with deeper water while higher abundance in summer and autumn (quarters 3 and 4) was associated with shallower water, consistent with seasonal onshore-offshore migrations but suggesting that most spawning may take place in deeper waters. The preferred SST range was generally 8-8.75 °C while preferred salinity values were below 35‰ in winter and summer and above 35‰ in spring and autumn. Squid were positively associated with gravel substrate and negatively associated with mud. Seasonal changes in habitat use were more clearly evident than changes related to inferred maturity, although the two effects cannot be fully separated due to the annual life cycle. Habitat selection for this species can be satisfactorily modelled on a seasonal basis; predictions based on such models could be useful for fishers to target the species more effectively, and could assist managers wishing to protect spawning grounds. The extent to which this approach may be useful for other cephalopods is discussed.

  2. The effect of shape distribution of inclusions on the frequency dependence of permeability in composites

    NASA Astrophysics Data System (ADS)

    Rozanov, K. N.; Osipov, A. V.; Petrov, D. A.; Starostenko, S. N.; Yelsukov, E. P.

    2009-04-01

    Microwave material parameters of composites filled with Fe powder are measured as a function of frequency and volume fraction of the powder. The powder is prepared by mechanical milling of Fe in argon atmosphere. The host matrix of the composites is paraffin wax. The permittivity and permeability are measured in the frequency range 0.01-3 GHz. The measured frequency dependences of the permeability is considered in terms of the Bergman-Milton theory, with no additional suggestions imposed on the volume fraction dependence of effective material parameters of composites and the frequency dependence of intrinsic permeability of magnetic powders. The Ghosh-Fuchs theory is found to provide an excellent agreement with the measured permittivity and permeability of the composites, in contrast to the theories employing averaged demagnetization factor of inclusions, such as the Maxwell Garnet approximation. Therefore, the effective material parameters of the composites are affected greatly by the shape distribution of the powder particles. From the measured frequency dependence of permittivity and permeability, the intrinsic permeability of the powder is found.

  3. Magnitude and distribution of stresses in composite resin and sound dentine interface with mechanical retentions

    PubMed Central

    Borie, Eduardo; Orsi, Iara-Augusta; Del Sol, Mariano

    2015-01-01

    Background Adhesive systems are constantly subjected to mechanical and chemical stresses that negatively impact the integrity and durability of the dentine-adhesive interface. Despite the lack of evidence to support or reject the clinical indication for mechanical retention, the potential further contribution of these preparations to the behavior of the composite resin-sound dentine bond has been rarely addressed. The authors evaluated by finite element analysis the effect of mechanical retention on the magnitude and distribution of stresses in a composite resin-sound dentin bonding interface when subjected to tensile and shear forces. Material and Methods A three-dimensional model was created based on three cylindrical volumes representing the sound dentin, adhesive system, and composite resin. From this main model, two models were designed to simulate dentine bonding: 1) a model with no mechanical retention, which considered flat adhesion; and 2) a model with retention, which considered four hemispherical holes on the dentine surface. Both groups were subjected to linear static analysis under tensile and shear loading of 200N. Results At the model with retentions’ bonding interface under tensile and shear loading, a concentration of Von Mises equivalent stress was observed within the retentions, with a reduction of those stresses on the bonding boundary surface. Conclusions Additional mechanical retention increases the tensile strength of the sound dentin-composite resin bonding interface, promoting a decrease in the magnitude of the stresses and their redistribution under tensile and shear loading. Key words:Adhesion, composite resins, dentine, finite element analysis. PMID:26155338

  4. Impact of early life ovariectomy on blood pressure and body composition in a female mouse model of systemic lupus erythematosus

    PubMed Central

    Gilbert, Emily L.

    2014-01-01

    Because of the preponderance of women affected by the chronic autoimmune disease systemic lupus erythematosus (SLE), estrogen is thought to contribute to SLE disease progression. This is supported by evidence from experimental animal models of SLE showing that removal of estrogen in young female mice delays autoantibody production and renal injury and lengthens survival. Blood pressure and changes in body composition are important cardiovascular risk factors that can be regulated by estrogens. Because cardiovascular disease is the leading cause of death in patients with SLE, we used an established female mouse model of SLE (NZBWF1) to test whether early life removal of estrogen impacts the development of hypertension and changes in body composition commonly associated with SLE. Eight-week-old female SLE and control mice (NZW/LacJ) underwent either a sham operation or ovariectomy. Body weight, body composition (fat and lean masses), and renal injury (albuminuria) were monitored until mice reached 34 wk of age, at which time mean arterial pressure was assessed in conscious animals by a carotid catheter. Early life removal of the ovaries delayed the onset of autoantibody production and albuminuria while causing an increase in body weight and fat mass. Blood pressure in the adult was not altered by early life removal of the ovaries. These data suggest that estrogens may have a permissive role for the development of SLE while helping to maintain normal body weight and composition, which is associated with reduced cardiovascular risk. PMID:25324553

  5. Software for analysis of chemical mixtures--composition, occurrence, distribution, and possible toxicity

    USGS Publications Warehouse

    Scott, Jonathon C.; Skach, Kenneth A.; Toccalino, Patricia L.

    2013-01-01

    The composition, occurrence, distribution, and possible toxicity of chemical mixtures in the environment are research concerns of the U.S. Geological Survey and others. The presence of specific chemical mixtures may serve as indicators of natural phenomena or human-caused events. Chemical mixtures may also have ecological, industrial, geochemical, or toxicological effects. Chemical-mixture occurrences vary by analyte composition and concentration. Four related computer programs have been developed by the National Water-Quality Assessment Program of the U.S. Geological Survey for research of chemical-mixture compositions, occurrences, distributions, and possible toxicities. The compositions and occurrences are identified for the user-supplied data, and therefore the resultant counts are constrained by the user’s choices for the selection of chemicals, reporting limits for the analytical methods, spatial coverage, and time span for the data supplied. The distribution of chemical mixtures may be spatial, temporal, and (or) related to some other variable, such as chemical usage. Possible toxicities optionally are estimated from user-supplied benchmark data. The software for the analysis of chemical mixtures described in this report is designed to work with chemical-analysis data files retrieved from the U.S. Geological Survey National Water Information System but can also be used with appropriately formatted data from other sources. Installation and usage of the mixture software are documented. This mixture software was designed to function with minimal changes on a variety of computer-operating systems. To obtain the software described herein and other U.S. Geological Survey software, visit http://water.usgs.gov/software/.

  6. Composition and distribution of elements and ultrastructural topography of a human cardiac calculus.

    PubMed

    Cheng, Ching-Li; Chang, Hsiao-Huang; Huang, Pei-Jung; Chu, Yu-Ting; Lin, Shan-Yang

    2013-04-01

    Trace elements (TEs) may contribute to the formation of calculi or stones or be involved in the aetiopathogenesis of stone diseases. The compositions and spatial distribution of elements from the inner nucleus to outer crust of the cardiac calculus were investigated by energy-dispersive X-ray fluorescence (EDXRF) spectrometer. The surface topograph, distribution map of elements, elemental and chemical compositions were also determined by environmental scanning electron microscope (ESEM)-energy-dispersive X-ray (EDX) analysis. Twenty-five elements were identifiable from 18 positions on the cardiac calculus by EDXRF spectrometer, in which the highest concentrations of toxic TEs (Ni, Pt, Hg, Sn, Pb, W, Au, Al, Si) and higher levels of essential TEs (Ca, Sr, Cr, P) were detected. A moderate positive Pearson's correlation between TEs concentrations of Mg, Ca or P and location differences from centre to periphery in the cardiac calculus was observed. A positive correlation was also found for Ca/Zn and Ca/Cu, indicating the gradual increase of calcium concentration from inner nucleus to outer crust of cardiac calculus. The drop-like nodules/crystals on the surface of petrous part of cardiac calculus were observed from ESEM analysis. ESEM-EDX analysis determined the calculus to be predominantly composed of calcium hydroxyapatite and cholesterol, as indicated by the petrous surface and drop-like nodules/crystals, respectively. This composition was confirmed using a portable Raman analyser. The spatial distribution analysis indicated a gradual increase in Mg, P and Ca concentrations from the inner nucleus to the outer crust of the cardiac calculus. The major chemical compositions of calcium hydroxyapatite and cholesterol were detected on this cardiac calculus. PMID:23404458

  7. Concept for Determining the Life of Ceramic Matrix Composites Using Nondestructive Characterization Techniques

    NASA Technical Reports Server (NTRS)

    Effinger, M.; Ellingson, B.; Spohnholtz, T.; Koenig, J.

    2001-01-01

    An idea is put forth for a nondestructive characterization (NDC) generated algorithm-N curve to replace a S-N curve. A scenario for NDC life determination has been proposed. There are many challenges for the NDC life determination and prediction, but it could yield a grand payoff. The justification for NDC life determination and prediction is documented.

  8. Accurate bearing remaining useful life prediction based on Weibull distribution and artificial neural network

    NASA Astrophysics Data System (ADS)

    Ben Ali, Jaouher; Chebel-Morello, Brigitte; Saidi, Lotfi; Malinowski, Simon; Fnaiech, Farhat

    2015-05-01

    Accurate remaining useful life (RUL) prediction of critical assets is an important challenge in condition based maintenance to improve reliability and decrease machine's breakdown and maintenance's cost. Bearing is one of the most important components in industries which need to be monitored and the user should predict its RUL. The challenge of this study is to propose an original feature able to evaluate the health state of bearings and to estimate their RUL by Prognostics and Health Management (PHM) techniques. In this paper, the proposed method is based on the data-driven prognostic approach. The combination of Simplified Fuzzy Adaptive Resonance Theory Map (SFAM) neural network and Weibull distribution (WD) is explored. WD is used just in the training phase to fit measurement and to avoid areas of fluctuation in the time domain. SFAM training process is based on fitted measurements at present and previous inspection time points as input. However, the SFAM testing process is based on real measurements at present and previous inspections. Thanks to the fuzzy learning process, SFAM has an important ability and a good performance to learn nonlinear time series. As output, seven classes are defined; healthy bearing and six states for bearing degradation. In order to find the optimal RUL prediction, a smoothing phase is proposed in this paper. Experimental results show that the proposed method can reliably predict the RUL of rolling element bearings (REBs) based on vibration signals. The proposed prediction approach can be applied to prognostic other various mechanical assets.

  9. Respiratory Chain Complexes in Dynamic Mitochondria Display a Patchy Distribution in Life Cells

    PubMed Central

    Muster, Britta; Kohl, Wladislaw; Wittig, Ilka; Strecker, Valentina; Joos, Friederike; Haase, Winfried; Bereiter-Hahn, Jürgen; Busch, Karin

    2010-01-01

    Background Mitochondria, the main suppliers of cellular energy, are dynamic organelles that fuse and divide frequently. Constraining these processes impairs mitochondrial is closely linked to certain neurodegenerative diseases. It is proposed that functional mitochondrial dynamics allows the exchange of compounds thereby providing a rescue mechanism. Methodology/Principal Findings The question discussed in this paper is whether fusion and fission of mitochondria in different cell lines result in re-localization of respiratory chain (RC) complexes and of the ATP synthase. This was addressed by fusing cells containing mitochondria with respiratory complexes labelled with different fluorescent proteins and resolving their time dependent re-localization in living cells. We found a complete reshuffling of RC complexes throughout the entire chondriome in single HeLa cells within 2–3 h by organelle fusion and fission. Polykaryons of fused cells completely re-mixed their RC complexes in 10–24 h in a progressive way. In contrast to the recently described homogeneous mixing of matrix-targeted proteins or outer membrane proteins, the distribution of RC complexes and ATP synthase in fused hybrid mitochondria, however, was not homogeneous but patterned. Thus, complete equilibration of respiratory chain complexes as integral inner mitochondrial membrane complexes is a slow process compared with matrix proteins probably limited by complete fusion. In co-expressing cells, complex II is more homogenously distributed than complex I and V, resp. Indeed, this result argues for higher mobility and less integration in supercomplexes. Conclusion/Significance Our results clearly demonstrate that mitochondrial fusion and fission dynamics favours the re-mixing of all RC complexes within the chondriome. This permanent mixing avoids a static situation with a fixed composition of RC complexes per mitochondrion. PMID:20689601

  10. Astrobiology: The Study of the Origin, Evolution, and Distribution of Life in the Universe

    ERIC Educational Resources Information Center

    Scalice, Daniella; Wilmoth, Krisstina

    2004-01-01

    Life as people know it here on Earth exchanges energy and materials with the environment. Life forms grow, develop, produce waste products, and reproduce, storing genetic information in DNA and RNA and passing it from one generation to the next. Life evolves, adapting to changes in the environment and changing the environment in return. The basic…

  11. Astrobiology: The Study of the Origin, Evolution, and Distribution of the Life in the Universe

    ERIC Educational Resources Information Center

    Scalice, Daniella; Wilmoth, Krisstina

    2004-01-01

    Life as known here on Earth exchanges energy and materials with the environment. Life forms grow, develop, produce waste products, and reproduce, storing genetic information in DNA and RNA and passing it from one generation to the next. Life evolves, adapting to changes in the environment and changing the environment in return. The basic unit of…

  12. Astrobiology: The Study of the Origin, Evolution, and Distribution of Life in the Universe

    ERIC Educational Resources Information Center

    Scalice, Daniella; Wilmoth, Krisstina

    2004-01-01

    Life as people know it here on Earth exchanges energy and materials with the environment. Life forms grow, develop, produce waste products, and reproduce, storing genetic information in DNA and RNA and passing it from one generation to the next. Life evolves, adapting to changes in the environment and changing the environment in return. The basic

  13. Astrobiology: The Study of the Origin, Evolution, and Distribution of the Life in the Universe

    ERIC Educational Resources Information Center

    Scalice, Daniella; Wilmoth, Krisstina

    2004-01-01

    Life as known here on Earth exchanges energy and materials with the environment. Life forms grow, develop, produce waste products, and reproduce, storing genetic information in DNA and RNA and passing it from one generation to the next. Life evolves, adapting to changes in the environment and changing the environment in return. The basic unit of

  14. Acoustic characterization of void distributions across carbon-fiber composite layers

    NASA Astrophysics Data System (ADS)

    Tayong, Rostand B.; Smith, Robert A.; Pinfield, Valerie J.

    2016-02-01

    Carbon Fiber Reinforced Polymer (CFRP) composites are often used as aircraft structural components, mostly due to their superior mechanical properties. In order to improve the efficiency of these structures, it is important to detect and characterize any defects occurring during the manufacturing process, removing the need to mitigate the risk of defects through increased thicknesses of structure. Such defects include porosity, which is well-known to reduce the mechanical performance of composite structures, particularly the inter-laminar shear strength. Previous work by the authors has considered the determination of porosity distributions in a fiber-metal laminate structure [1]. This paper investigates the use of wave-propagation modeling to invert the ultrasonic response and characterize the void distribution within the plies of a CFRP structure. Finite Element (FE) simulations are used to simulate the ultrasonic response of a porous composite laminate to a typical transducer signal. This simulated response is then applied as input data to an inversion method to calculate the distribution of porosity across the layers. The inversion method is a multi-dimensional optimization utilizing an analytical model based on a normal-incidence plane-wave recursive method and appropriate mixture rules to estimate the acoustical properties of the structure, including the effects of plies and porosity. The effect of porosity is defined through an effective wave-number obtained from a scattering model description. Although a single-scattering approach is applied in this initial study, the limitations of the method in terms of the considered porous layer, percentage porosity and void radius are discussed in relation to single- and multiple-scattering methods. A comparison between the properties of the modeled structure and the void distribution obtained from the inversion is discussed. This work supports the general study of the use of ultrasound methods with inversion to characterize material properties and any defects occurring in composites structures in three dimensions. This research is part of a Fellowship in Manufacturing funded by the UK Engineering and Physical Sciences Research Council (EPSRC) aimed at underpinning the design of more efficient composite structures and reducing the environmental impact of travel.

  15. Life cycle strain mapping of composite airframe structures by using FBG sensors

    NASA Astrophysics Data System (ADS)

    Sekine, K.; Takahashi, I.; Kume, M.; Takeya, H.; Iwahori, Y.; Minakuchi, S.; Takeda, N.; Koshioka, Y.

    2011-04-01

    The objective of this work is to develop a system for monitoring the structural integrity of composite airframe structures by strain mapping over the entire lifecycle of the structure. Specifically, we use fiber Bragg grating sensors to measure strain in a pressure bulkhead made of carbon fiber reinforced plastics (CFRPs) through a sequence of lifecycle stages (molding, machining, assembly, operation and maintenance) and detect the damage, defects, and deformation that occurs at each stage from the obtained strain distributions. In previous work, we have evaluated strain monitoring at each step in the FRP molding and machining stages of the lifecycle. In the work reported here, we evaluate the monitoring of the changes in strain that occur at the time of bolt fastening during assembly. The results show that the FBG sensors can detect the changes in strain that occur when a load is applied to the structure during correction of thermal deformation or when there is an offset in the hole position when structures are bolted together. We also conducted experiments to evaluate the detection of damage and deformation modes that occur in the pressure bulkhead during operation. Those results show that the FBG sensors detect the characteristic changes in strain for each mode.

  16. Phylogenetic diversity, composition and distribution of bacterioplankton community in the Dongjiang River, China.

    PubMed

    Liu, Zhenghui; Huang, Shaobin; Sun, Guoping; Xu, Zhencheng; Xu, Meiying

    2012-04-01

    Bacterioplankton community compositions in the Dongjiang River were characterized using denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library construction. Water samples in nine different sites were taken along the mainstem and three tributaries. In total, 24 bands from DGGE gels and 406 clones from the libraries were selected and sequenced, subsequently analyzed for the bacterial diversity and composition of those microbial communities. Bacterial 16S rRNA gene sequences from freshwater bacteria exhibited board phylogenetic diversity, including sequences representing the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, Bacteriodetes, Verrucomicrobia, and candidate division TM7. Members of Betaproteobacteria group were the most dominant in all sampling sites, followed by Gammaproteobacteria, Alphaproteobacteria, and Actinobacteria. DGGE profiles and the ∫-LIBSHUFF analysis revealed similar patterns of bacterial diversity among most sampling sites, while spatial distribution variances existed in all sites along the river basin. Statistical analysis showed that bacterial species distribution strongly correlated with environmental variables, such as nitrate and ammonia, suggesting that nitrogen nutrients may shape the microbial community structure and composition in the Dongjiang River. This study had important implications for the comparison with other rivers elsewhere and contributed to the growing data set on the factors that structure bacterial communities in freshwater ecosystems. PMID:22133045

  17. Evaluation of flawed composite structural components under static and cyclic loading. [fatigue life of graphite-epoxy composite materials

    NASA Technical Reports Server (NTRS)

    Porter, T. R.

    1979-01-01

    The effects of initial defects on the fatigue and fracture response of graphite-epoxy composite laminates are presented. The structural laminates investigated were a typical angle ply laminate, a polar/hoop wound pressure vessel laminate, and a typical engine fan blade laminate. Defects investigated were full and half penetration circular holes, full and half penetration slits, and countersink holes. The effects of the defect size and type on the static fracture strength, fatigue performance, and residual static strength are shown as well as the results of loadings on damage propagation in composite laminates. The data obtained were used to define proof test levels as a qualification procedure in composite structure subjected to cyclic loading.

  18. Local Abundance Patterns of Noctuid Moths in Olive Orchards: Life-History Traits, Distribution Type and Habitat Interactions

    PubMed Central

    Pérez-Guerrero, Sergio; Redondo, Alberto José; Yela, José Luis

    2011-01-01

    Local species abundance is related to range size, habitat characteristics, distribution type, body size, and life-history variables. In general, habitat generalists and polyphagous species are more abundant in broad geographical areas. Underlying this, local abundance may be explained from the interactions between life-history traits, chorological pattern, and the local habitat characteristics. The relationship within taxa between life-history traits, distribution area, habitat characteristics, and local abundance of the noctuid moth (Lepidoptera: Noctuidae) assemblage in an olive orchard, one of the most important agro-ecosystems in the Mediterranean basin, was analyzed. A total of 66 species were detected over three years of year-round weekly samplings using the light-trap method. The life-history traits examined and the distribution type were found to be related to the habitat-species association, but none of the biological strategies defined from the association to the different habitats were linked with abundance. In contrast to general patterns, dispersal ability and number of generations per year explained differences in abundance. The relationships were positive, with opportunistic taxa that have high mobility and several generations being locally more abundant. In addition, when the effect of migrant species was removed, the distribution type explained abundance differences, with Mediterranean taxa (whose baricenter is closer to the studied area) being more abundant. PMID:21529251

  19. The effect of mesostructure heterogeneity on cracks initiation and the displacement distribution in NCF composites

    NASA Astrophysics Data System (ADS)

    Zrida, H.; Giannadis, K.; Varna, J.; Ayadi, Z.

    2012-02-01

    Non Crimp Fabrics (NCF) are promising new generation composite materials. They are now being used in some sections of composite industry, for example in wind turbine blades and boat hulls. The aerospace industry also shows an increasing interest in this material, thanks to the low cost of its manufacturing process. NCFs are special types of textile composites, made of layers of parallel fiber bundles oriented in different directions and separated by resin. Due to the manufacturing process the fiber bundles are not perfectly straight. They show a certain degree of waviness which decreases the stiffness and the strength of the material. The heterogeneous mesostructure affects the mechanical properties of the material and the failure mechanisms. This was studied using both numerical and experimental methods. In our experimental approach, a carbon fiber/epoxy resin laminate with uniform fiber distribution was manufactured by voluntarily introducing waviness to simulate the NCF composites. The displacement map was studied against the thickness of a sample loaded in tension, using ESPI (Electronic Speckle Pattern Interferometry). This can give us a primary idea of the micro damage initiation and the cracks' shapes.

  20. Characterization of reinforcement distribution in cast Al-alloy/SiC{sub p} composites

    SciTech Connect

    Karnezis, P.A.; Durrant, G.; Cantor, B.

    1998-02-01

    The distribution of reinforcement in 10% SiC and 20% SiC{sub p} reinforced A356 alloy processed by gravity casting, squeeze casting, and roll casting is studied by using the mean free path, nearest neighbor distance, radial distribution function, and quadrat methods. The study is performed by using computer image analysis methods in an automated procedure to prevent operator errors, improve sample size, and minimize analysis time. From the methods used to characterize the SiC{sub p} distributions, the quadrat method and radial distribution function are found to be more effective in detecting pronounced changes in the metal-matrix composite (MMC) microstructure through appropriate parameters, whereas the mean free path is characteristic of the particular MMC system rather than process specific. Furthermore, the nearest neighbor distance is of little use in studying cast MMCs, because it is affected by local clusters of a few SiC particles commonly found in cast MMCs, thus failing to characterize the macroscopic arrangement of reinforcement. Quantitative methods present themselves as a useful tool for quality control in MMC fabrication and can be used to correlate particle distribution and properties of MMC systems.

  1. Characterization of macromolecular complexes in red wine: Composition, molecular mass distribution and particle size.

    PubMed

    Bindon, Keren A; Carew, Anna L; Mierczynska-Vasilev, Agnieszka; Kassara, Stella; Kerslake, Fiona; Smith, Paul A

    2016-05-15

    Precipitates were prepared from two compositionally different Pinot noir wines with addition of excess ethanol, and contained primarily polysaccharide, tannin and protein. The ethanol-soluble material was further fractionated into polymeric (tannin) and monomeric phenolics. Tannin associated with precipitates was of a higher molecular mass than that remaining in ethanolic solution. Wine fractions were reconstituted at the ratios of the original wine and analyzed using nanoparticle tracking analysis. The average particle size of the tannin fraction was 75-89 nm, and increased when combined with the precipitate (≅ 200 nm). Addition of the monomeric fraction to the tannin-precipitate complex increased both the incidence and concentration of smaller particles, reducing the average particle size. The formation of aggregates occurred in all fractions and only minor differences in particle size distribution were found between wines. Differences in particle concentration between wines appear to be due to differences in the total concentration of macromolecules rather than compositional differences. PMID:26776042

  2. Reliability and life prediction of ceramic composite structures at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Duffy, Stephen F.; Gyekenyesi, John P.

    1994-01-01

    Methods are highlighted that ascertain the structural reliability of components fabricated of composites with ceramic matrices reinforced with ceramic fibers or whiskers and subject to quasi-static load conditions at elevated temperatures. Each method focuses on a particular composite microstructure: whisker-toughened ceramics, laminated ceramic matrix composites, and fabric reinforced ceramic matrix composites. In addition, since elevated service temperatures usually involve time-dependent effects, a section dealing with reliability degradation as a function of load history has been included. A recurring theme throughout this chapter is that even though component failure is controlled by a sequence of many microfailure events, failure of ceramic composites will be modeled using macrovariables.

  3. General models for resource use or other compositional count data using the Dirichlet-multinomial distribution.

    PubMed

    De Valpine, Perry; Harmon-Threatt, Alexandra N

    2013-12-01

    Many ecological studies investigate how organisms use resources, such as habitats or foods, in relation to availability or other variables. Related statistical problems include analysis of proportions of species or genotypes in a community or population. These require statistical modeling of compositional count data: data on relative proportions of each category collected as counts. Common methods for analyzing compositional count data lack one or more important considerations. Some methods lack explicit accommodation of count data, dealing instead with proportions. Others do not handle between-sample heterogeneity for overdispersed data. Yet others do not allow general types of relationships between explanatory variables and resource use. All three components have been combined in a Bayesian framework, but for frequentist hypothesis tests and AIC model selection, maximum-likelihood estimation is needed. Here we propose the Dirichlet-multinomial distribution to accommodate overdispersed compositional count data. This approach can be used flexibly in combination with explanatory models, but the only correlations among compositional proportions that it can accommodate are the negative correlations due to the fact that proportions must sum to 1. Many existing models can be generalized to use the Dirichlet-multinomial distribution for residual variation, and the flexibility of the approach allows new hypotheses that have often not been considered in resource preference analysis, including that availability has no relation to use. We also highlight a new design for resource use studies, with multiple individual-use data sets from each of multiple sites, with different explanatory data for each site. We illustrate the approach with three examples. For two previously published habitat use data sets, we support the original conclusions and show that use is not unrelated to availability. For a data set of pollen collected by multiple bees from each of two sites, pollen use differs between the sites. Using bootstrap goodness-of-fit tests, we illustrate that the Dirichlet-multinomial is acceptable for two of the examples but unsuitable for one of the habitat use examples. PMID:24597215

  4. Free-standing carbon nanotube composite sensing skin for distributed strain sensing in structures

    NASA Astrophysics Data System (ADS)

    Burton, Andrew R.; Minegishi, Kaede; Kurata, Masahiro; Lynch, Jerome P.

    2014-04-01

    The technical challenges of managing the health of critical infrastructure systems necessitate greater structural sensing capabilities. Among these needs is the ability for quantitative, spatial damage detection on critical structural components. Advances in material science have now opened the door for novel and cost-effective spatial sensing solutions specially tailored for damage detection in structures. However, challenges remain before spatial damage detection can be realized. Some of the technical challenges include sensor installations and extensive signal processing requirements. This work addresses these challenges by developing a patterned carbon nanotube composite thin film sensor whose pattern has been optimized for measuring the spatial distribution of strain. The carbon nanotube-polymer nanocomposite sensing material is fabricated on a flexible polyimide substrate using a layer-by-layer deposition process. The thin film sensors are then patterned into sensing elements using optical lithography processes common to microelectromechanical systems (MEMS) technologies. The sensor array is designed as a series of sensing elements with varying width to provide insight on the limitations of such patterning and implications of pattern geometry on sensing signals. Once fabrication is complete, the substrate and attached sensor are epoxy bonded to a poly vinyl composite (PVC) bar that is then tested with a uniaxial, cyclic load pattern and mechanical response is characterized. The fabrication processes are then utilized on a larger-scale to develop and instrument a component-specific sensing skin in order to observe the strain distribution on the web of a steel beam. The instrumented beam is part of a larger steel beam-column connection with a concrete slab in composite action. The beam-column subassembly is laterally loaded and strain trends in the web are observed using the carbon nanotube composite sensing skin. The results are discussed in the context of understanding the properties of the thin film sensor and how it may be advanced toward structural sensing applications.

  5. Cyanobacterial composition and spatial distribution based on pyrosequencing data in the Gurbantunggut Desert, Northwestern China.

    PubMed

    Zhang, Bingchang; Li, Renhui; Xiao, Peng; Su, Yangui; Zhang, Yuanming

    2016-03-01

    Cyanobacteria are the primary colonizers and form a dominant component of soil photosynthetic communities in biological soil crusts. They are crucial in improving soil environments, namely accumulating soil carbon and nitrogen. Many classical studies have examined cyanobacterial diversity in desert crusts, but relatively few comprehensive molecular surveys have been conducted. We used 454 pyrosequencing of 16S rRNA to investigate cyanobacterial composition and distribution on regional scales in the Gurbantunggut Desert. The relationship between cyanobacterial distribution and environmental factors was also explored. A total of 24,973 cyanobacteria partial 16S rRNA gene sequences were obtained, and 507OTUs were selected, as most OTUs had very few reads. Among these, 347 OTU sequences were of cyanobacteria origin, belonging to Oscillatoriales, Nostocales, Chroococcales, and uncultured cyanobacterium clone, respectively. Microcoleus vaginatus, Chroococcidiopsis spp. and M. steenstrupii were the dominant species in most areas of the Gurbantunggut Desert. Compared with other desert, the Gurbantunggut Desert differed in the prominence of Chroococcidiopsis spp. and lack of Pseudanabaenales. Species composition and abundance of cyanobacteria also showed distinct variations. Soil texture, precipitation, and nutrients and salt levels affected cyanobacterial distribution. Increased precipitation was helpful in improving cyanobacterial diversity. A higher content of coarse sand promoted the colonization and growth of Oscillatoriales and some phylotypes of Chroococcales. The fine-textured soil with higher nutrients and salts supported more varied populations of cyanobacteria, namely some heterocystous cyanobacteria. The results suggested that the Gurbantunggut Desert was rich in cyanobacteria and that precipitation was a primary regulating factor for cyanobacterial composition on a regional scale. PMID:26479723

  6. A Model to Predict Shelf-Life Loss Ofhorticultural Produce During Distribution Withfluctuated Temperature and Vehicle Vibration

    NASA Astrophysics Data System (ADS)

    Gong, Weiwei; Li, Daoliang; Liu, Xue; Yue, Jun; Fu, Zetian

    Fresh fruits and vegetables has become a public concern from the food security aspect. And the prediction of shelf-life loss under the fluctuated temperature becomes one of the key problems in food supply chain operation. So this paper identifies the impact aspects of produce decaying during distribution. For the key temperature factor, the process is divided into three phases: sorting, traveling and door-opening. Based on time-temperature function, a model of shelf-life loss of horticultural produce during distribution is developed by evaluating respiration rate of vegetables and fruits considering both the environment fluctuated temperature and vehicle vibration during traveling. Taking eggplant as an example, the numerical experiment result demonstrates that the average cost for ambient distribution is 2.8 times of the insulation way.

  7. The stress distribution and curvature of a general compositionally graded semiconductor layer

    NASA Astrophysics Data System (ADS)

    Freud, L. B.

    1993-09-01

    The physical system considered is a thin, strained-layer structure. It is shown that the stress distribution and curvature for such a structure, with arbitrary compositional gradiation and with general thickness variation of temperature of epitaxial mismatch strain can be determined by means of elementary formulae. As an illustration, the results are applied to compute the stress in a GaAs/In xGa 1- xAs/In 0.12Ga 0.88As ternary epitaxial structure with X varying through the thickness of the 1185 middle layer.

  8. Direct Determination of 3D Distribution of Elemental Composition in Single Semiconductor Nanoislands by Scanning Auger Microscopy

    NASA Astrophysics Data System (ADS)

    Ponomaryov, Semyon S.; Yukhymchuk, Volodymyr O.; Lytvyn, Peter M.; Valakh, Mykhailo Ya

    2016-02-01

    An application of scanning Auger microscopy with ion etching technique and effective compensation of thermal drift of the surface analyzed area is proposed for direct local study of composition distribution in the bulk of single nanoislands. For GexSi1 - x-nanoislands obtained by MBE of Ge on Si-substrate gigantic interdiffusion mixing takes place both in the open and capped nanostructures. Lateral distributions of the elemental composition as well as concentration-depth profiles were recorded. 3D distribution of the elemental composition in the d-cluster bulk was obtained using the interpolation approach by lateral composition distributions in its several cross sections and concentration-depth profile. It was shown that there is a germanium core in the nanoislands of both nanostructure types, which even penetrates the substrate. In studied nanostructures maximal Ge content in the nanoislands may reach about 40 at.%.

  9. On the Relationship Between Site Geology and the Distribution of Surface Regolith Compositions at the Apollo Sites

    NASA Technical Reports Server (NTRS)

    Korotev, Randy L.

    2000-01-01

    Some considerations are discussed on how information on site geology can be obtained from the distribution of data points on 2-element plots of composition of lunar regolith samples collected along a traverse.

  10. Direct Determination of 3D Distribution of Elemental Composition in Single Semiconductor Nanoislands by Scanning Auger Microscopy.

    PubMed

    Ponomaryov, Semyon S; Yukhymchuk, Volodymyr O; Lytvyn, Peter M; Valakh, Mykhailo Ya

    2016-12-01

    An application of scanning Auger microscopy with ion etching technique and effective compensation of thermal drift of the surface analyzed area is proposed for direct local study of composition distribution in the bulk of single nanoislands. For GexSi1 - x-nanoislands obtained by MBE of Ge on Si-substrate gigantic interdiffusion mixing takes place both in the open and capped nanostructures. Lateral distributions of the elemental composition as well as concentration-depth profiles were recorded. 3D distribution of the elemental composition in the d-cluster bulk was obtained using the interpolation approach by lateral composition distributions in its several cross sections and concentration-depth profile. It was shown that there is a germanium core in the nanoislands of both nanostructure types, which even penetrates the substrate. In studied nanostructures maximal Ge content in the nanoislands may reach about 40 at.%. PMID:26909783

  11. Opisthorchis viverrini: life cycle, intermediate hosts, transmission to man and geographical distribution in Thailand.

    PubMed

    Harinasuta, C; Harinasuta, T

    1984-01-01

    Opisthorchis viverrini has been found to be the only species of liver fluke in Thailand. The morphology is similar to that of O. felineus, but it has more deeply lobated testes, situated near the ovary. The appearance and distribution of the vitellaria with few granular clumps and the shorter and wider egg closely resemble that of C. sinensis. The adult worms live in the biliary system. Eggs pass out in faeces. On reaching water the eggs are eaten by snails, the first intermediate host. In the snail the miracidia hatch and develop further through the stages of sporocysts, rediae and cercariae in six to eight weeks. The cercariae then leave the snail, penetrate into susceptible fresh water fish, encyst in the muscle and develop into metacercariae, and infective stage, in six weeks. When ingested by man or animal the metacercariae excyst in the duodenum or jejunum and then migrate to the bile duct. They become mature within four weeks and begin to produce eggs. The life span of the fluke is over 10 years. The snail intermediate hosts are Bithynia goniomphalus, B. funiculata and B. siamensis. Many species of cyprinoid fish serve as second intermediate host; Cyclocheilichthys siaja is the most important. Cats, dogs and many fish eating mammals are definitive hosts. Man and animals acquire infection by eating raw fish containing metacercariae cysts. In Northeast Thailand "Koi-Pla" is the most popular raw fish dish. In 1980-1981 the prevalence in the north, northeast, centre and south of Thailand was 5.59, 34.60, 6.34, and 0.01%, respectively, with an overall prevalence of 14% or 7 million people. PMID:6542383

  12. [Species composition and ecological distribution of macrofungi in Huangpushan Natural Reserve of Anhui Province].

    PubMed

    Chai, Xin-Yi

    2010-01-01

    In order to understand and utilize the macrofungal resources in Huangpushan Natural Reserve of Anhui Province, their species composition and ecological distribution were investigated, and a comprehensive evaluation was made. A total of 87 macrofungal species were recorded, belonging to 46 genera, 22 families, 6 orders and 4 classes. They were widely distributed in broadleaf forest, coniferous forest, mixed broadleaf and coniferous forest, bamboo forest, and wasteland. According to their economic values, there were 42 edible species, 31 medicinal species, and 6 poisonous species; based on their ecological habitats, they were categorized into humicolous (44 species), lignicolous (30), ectomycorrhizal (19), and entomogenous species (2). The macro-fungi in the Reserve had great prospects of applying in food, medicine, and forestation. PMID:20387440

  13. Astrobiology: exploring the origins, evolution, and distribution of life in the Universe

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.; Walter, M. R.

    1999-01-01

    The search for the origins of life and its presence beyond Earth is strengthened by new technology and by evidence that life tolerates extreme conditions and that planets are widespread. Astrobiologists learn how planets develop and maintain habitable conditions. They combine biological and information sciences to decipher the origins of life. They examine how biota, particularly microorganisms, evolve, at scales from the molecular to the biosphere level, including interactions with long-term planetary changes. Astrobiologists learn how to recognize the morphological, chemical, and spectroscopic signatures of life in order to explore both extraterrestrial samples and electromagnetic spectra reflected from extrasolar planets.

  14. Distributed sensing of Composite Over-wrapped Pressure Vessels using Fiber-Bragg Gratings

    NASA Technical Reports Server (NTRS)

    Grant, Joseph

    2005-01-01

    The increasing use of advanced composite materials in the wide range of applications including Space Structures is a great impetus to the development of smart materials. These materials offer a wide range of possibilities within the space program. But before they can be reliably incorporated into space flight applications, additional understanding is required in the area of damage tolerance of these materials. Efforts to enhance our understanding of failure modes, mechanical properties, long and short term environmental effects, cyclic damage accumulation and residual strength are needed. Thus we have employed the use of fiber optical sensors which offers an excellent opportunity exploit these materials through monitoring and characterizing their mechanical properties and thus the integrity of structures made from such materials during their life cycle. Use of these optical innovations provides an insight into structures that have not been available in the past, as well as the technology available to provide real time health monitoring throughout its life cycle. The embedded fiber optical sensor shows a clearly detectable sensitivity to changes in the near strain and stress fields of the host structure promoted by mechanical or thermal loading or, in certain conditions, structural damage. The last ten years have seen a large increase in the use of FBG based monitoring systems in a broad range of applications. Fiber Bragg gratings are use to monitor the structural properties of composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in composite structures. The fiber Bragg sensors are both embedded within the composite laminates and bonded to the surface of the vessel with varying orientations with respect to the carbon fiber in the epoxy matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 4400 psi. This is done at both ambient and cryogenic temperatures using water and liquid nitrogen. The recorded response is compared with the response from conventional strain gauge also present on the vessel. Additionally, several vessels were tested that had been damaged to simulate different type of events, such as cut tow, delimitation and impact damage.

  15. Somatic Maintenance Resources in the Honeybee Worker Fat Body Are Distributed to Withstand the Most Life-Threatening Challenges at Each Life Stage

    PubMed Central

    Seehuus, Siri-Christine; Taylor, Simon; Petersen, Kjell; Aamodt, Randi M.

    2013-01-01

    In a global transcriptome analysis of three natural and three manipulated honeybee worker phenotypes at different ages, we have investigated the distribution of investment in somatic maintenance of the fat body. Gene expression is modulated so that the bees are able to resist the most life-threatening challenges at the actual life stage. Different modes of maintenance and repair are regulated, apparently to meet the environmental challenges most detrimental to survival and reproductive potential for the hive. We observed a broad down-regulation of genomic and cellular maintenance in the short-lived foragers and nurse bees compared to the long-lived winter bees. Our results show that survival and reproduction of the entire hive is given priority over the individual bees, hence supporting the idea of the honeybee society as a superorganism. Our results also fit the disposable soma theory of aging. PMID:23940531

  16. A compact analytic method for stress distribution in composite pinned joints

    NASA Astrophysics Data System (ADS)

    Aluko, Olanrewaju

    An analysis was performed to evaluate the stress distribution in composite pin loaded joints. In this analysis involving a push fit pin, the pin was modeled as rigid and the plate as an infinite orthotropic plate. The analysis involves first the specification of displacement expressions in form of a trigonometric series that satisfy the boundary conditions for the contact region in terms of a set of undetermined coefficients. Based on this assumed distribution, the Lekhnitskii complex variable approach is used to obtain the stress functions needed to evaluate the contact stress within the joint. Unknown coefficients in the displacement expression were obtained by assuming coulomb friction within the contact region and then evaluating the displacement at discrete points within this region. Material properties of carbon fiber reinforced plastic laminates and a graphite-epoxy laminate was used for the study and the stress distribution for various values of coefficient of friction analyzed and the results compared with the previous investigations. This analysis reveals that friction has a pronounced effect on stress distribution around the hole boundary.

  17. On the limit theorem for life time distribution connected with some reliability systems and their validation by means of the Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Gheorghe, Munteanu Bogdan; Alexei, Leahu; Sergiu, Cataranciuc

    2013-09-01

    We prove the limit theorem for life time distribution connected with reliability systems when their life time is a Pascal Convolution of independent and identically distributed random variables. We show that, in some conditions, such distributions may be approximated by means of Erlang distributions. As a consequnce, survival functions for such systems may be, respectively, approximated by Erlang survival functions. By using Monte Carlo method we experimantally confirm the theoretical results of our theorem.

  18. 12 CFR 2.3 - Distribution of credit life insurance income.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... percent), who is involved in the sale of credit life insurance to loan customers of the national bank, to... insurance in connection with any loan made by that bank, and income from credit life insurance sales to loan... insurance should be based on the benefits of the policy, not the commissions received from the sale....

  19. The distribution of compositional classes in the asteroid belt: A cosmochemical fingerprint?

    NASA Technical Reports Server (NTRS)

    Gradie, J.

    1985-01-01

    Studies of the physical properties of the asteroids show a nonrandom distribution of types across the belt for asteroid classes E, S, M, F, C, P, and D. The general trend is for asteroids in the inner belt to have higher albedos and stronger mafic silicate absorption features than those asteroids located further out in the belt. One interpretation of this trend is that the asteroids, which occupy the region between the silicate rich terrestrial planets and the volatile rich outer planets, have preserved in their heliocentric compositional distribution a cosmochemical fingerprint of the thermodynamic conditions present in the solar nebula at the time of their formation. This hypothesis predicts that the differences in the spectral properties among the low albedo classes (C, P, F, P, and D) are due to temperature controlled processes which formed carbonaceous opaques. If this is true then the exact composition of the opaque components could, in principle, be used to determine the thermodynamic conditions between the orbits of Mars and Jupiter during the formation of the asteroids.

  20. Altered potassium channel distribution and composition in myelinated axons suppresses hyperexcitability following injury.

    PubMed

    Calvo, Margarita; Richards, Natalie; Schmid, Annina B; Barroso, Alejandro; Zhu, Lan; Ivulic, Dinka; Zhu, Ning; Anwandter, Philipp; Bhat, Manzoor A; Court, Felipe A; McMahon, Stephen B; Bennett, David Lh

    2016-01-01

    Neuropathic pain following peripheral nerve injury is associated with hyperexcitability in damaged myelinated sensory axons, which begins to normalise over time. We investigated the composition and distribution of shaker-type-potassium channels (Kv1 channels) within the nodal complex of myelinated axons following injury. At the neuroma that forms after damage, expression of Kv1.1 and 1.2 (normally localised to the juxtaparanode) was markedly decreased. In contrast Kv1.4 and 1.6, which were hardly detectable in the naïve state, showed increased expression within juxtaparanodes and paranodes following injury, both in rats and humans. Within the dorsal root (a site remote from injury) we noted a redistribution of Kv1-channels towards the paranode. Blockade of Kv1 channels with α-DTX after injury reinstated hyperexcitability of A-fibre axons and enhanced mechanosensitivity. Changes in the molecular composition and distribution of axonal Kv1 channels, therefore represents a protective mechanism to suppress the hyperexcitability of myelinated sensory axons that follows nerve injury. PMID:27033551

  1. Real-Time Impact Visualization Inspection of Aerospace Composite Structures with Distributed Sensors

    PubMed Central

    Si, Liang; Baier, Horst

    2015-01-01

    For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor and predict the locations and force magnitudes of unforeseen foreign impacts on composite structures and to estimate in real time mode the structural state when impacts occur. The proposed smart impact visualization inspection (IVI) technique mainly consists of five functional modules, which are the signal data preprocessing (SDP), the forward model generator (FMG), the impact positioning calculator (IPC), the inverse model operator (IMO) and structural state estimator (SSE). With regard to the verification of the practicality of the proposed IVI technique, various structure configurations are considered, which are a normal CFRP panel and another CFRP panel with “orange peel” surfaces and a cutout hole. Additionally, since robustness against several background disturbances is also an essential criterion for practical engineering demands, investigations and experimental tests are carried out under random vibration interfering noise (RVIN) conditions. The accuracy of the predictions for unknown impact events on composite structures using the IVI technique is validated under various structure configurations and under changing environmental conditions. The evaluated errors all fall well within a satisfactory limit range. Furthermore, it is concluded that the IVI technique is applicable for impact monitoring, diagnosis and assessment of aerospace composite structures in complex practical engineering environments. PMID:26184196

  2. Central Appalachian basin natural gas database: distribution, composition, and origin of natural gases

    USGS Publications Warehouse

    Román Colón, Yomayra A.; Ruppert, Leslie F.

    2015-01-01

    The U.S. Geological Survey (USGS) has compiled a database consisting of three worksheets of central Appalachian basin natural gas analyses and isotopic compositions from published and unpublished sources of 1,282 gas samples from Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The database includes field and reservoir names, well and State identification number, selected geologic reservoir properties, and the composition of natural gases (methane; ethane; propane; butane, iso-butane [i-butane]; normal butane [n-butane]; iso-pentane [i-pentane]; normal pentane [n-pentane]; cyclohexane, and hexanes). In the first worksheet, location and American Petroleum Institute (API) numbers from public or published sources are provided for 1,231 of the 1,282 gas samples. A second worksheet of 186 gas samples was compiled from published sources and augmented with public location information and contains carbon, hydrogen, and nitrogen isotopic measurements of natural gas. The third worksheet is a key for all abbreviations in the database. The database can be used to better constrain the stratigraphic distribution, composition, and origin of natural gas in the central Appalachian basin.

  3. Modified oleic cottonseeds show altered content, composition and tissue-specific distribution of triacylglycerol molecular species.

    PubMed

    Horn, Patrick J; Sturtevant, Drew; Chapman, Kent D

    2014-01-01

    Targeted increases in monounsaturated (oleic acid) fatty acid content of refined cottonseed oil could support improved human nutrition and cardiovascular health. Genetic modifications of cottonseed fatty acid composition have been accomplished using several different molecular strategies. Modification of oleic acid content in cottonseed embryos using a dominant-negative protein approach, while successful in effecting change in the desired fatty acid composition, resulted in reduced oil content and seed viability. Here these changes in fatty acid composition were associated with changes in dominant molecular species of triacylglycerols (TAGs) and their spatial distributions within embryo tissues. A combination of mass spectrometry (MS)-based lipidomics approaches, including MS imaging of seed cryo-sections, revealed that cotton embryos expressing a non-functional allele of a Brassica napus delta-12 desaturase showed altered accumulation of TAG species, especially within cotyledonary tissues. While lipid analysis of seed extracts could demonstrate detailed quantitative changes in TAG species in transgenics, the spatial contribution of metabolite compartmentation could only be visualized by MS imaging. Our results suggest tissue-specific differences in TAG biosynthetic pathways within cotton embryos, and indicate the importance of considering the location of metabolites in tissues in addition to their identification and quantification when developing a detailed view of cellular metabolism. PMID:23973433

  4. Real-Time Impact Visualization Inspection of Aerospace Composite Structures with Distributed Sensors.

    PubMed

    Si, Liang; Baier, Horst

    2015-01-01

    For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor and predict the locations and force magnitudes of unforeseen foreign impacts on composite structures and to estimate in real time mode the structural state when impacts occur. The proposed smart impact visualization inspection (IVI) technique mainly consists of five functional modules, which are the signal data preprocessing (SDP), the forward model generator (FMG), the impact positioning calculator (IPC), the inverse model operator (IMO) and structural state estimator (SSE). With regard to the verification of the practicality of the proposed IVI technique, various structure configurations are considered, which are a normal CFRP panel and another CFRP panel with "orange peel" surfaces and a cutout hole. Additionally, since robustness against several background disturbances is also an essential criterion for practical engineering demands, investigations and experimental tests are carried out under random vibration interfering noise (RVIN) conditions. The accuracy of the predictions for unknown impact events on composite structures using the IVI technique is validated under various structure configurations and under changing environmental conditions. The evaluated errors all fall well within a satisfactory limit range. Furthermore, it is concluded that the IVI technique is applicable for impact monitoring, diagnosis and assessment of aerospace composite structures in complex practical engineering environments. PMID:26184196

  5. Receptor modelling of both particle composition and size distribution from a background site in London, UK

    NASA Astrophysics Data System (ADS)

    Beddows, D. C. S.; Harrison, R. M.; Green, D. C.; Fuller, G. W.

    2015-09-01

    Positive matrix factorisation (PMF) analysis was applied to PM10 chemical composition and particle number size distribution (NSD) data measured at an urban background site (North Kensington) in London, UK, for the whole of 2011 and 2012. The PMF analyses for these 2 years revealed six and four factors respectively which described seven sources or aerosol types. These included nucleation, traffic, urban background, secondary, fuel oil, marine and non-exhaust/crustal sources. Urban background, secondary and traffic sources were identified by both the chemical composition and particle NSD analysis, but a nucleation source was identified only from the particle NSD data set. Analysis of the PM10 chemical composition data set revealed fuel oil, marine, non-exhaust traffic/crustal sources which were not identified from the NSD data. The two methods appear to be complementary, as the analysis of the PM10 chemical composition data is able to distinguish components contributing largely to particle mass, whereas the number particle size distribution data set - although limited to detecting sources of particles below the diameter upper limit of the SMPS (604 nm) - is more effective for identifying components making an appreciable contribution to particle number. Analysis was also conducted on the combined chemical composition and NSD data set, revealing five factors representing urban background, nucleation, secondary, aged marine and traffic sources. However, the combined analysis appears not to offer any additional power to discriminate sources above that of the aggregate of the two separate PMF analyses. Day-of-the-week and month-of-the-year associations of the factors proved consistent with their assignment to source categories, and bivariate polar plots which examined the wind directional and wind speed association of the different factors also proved highly consistent with their inferred sources. Source attribution according to the air mass back trajectory showed, as expected, higher concentrations from a number of source types in air with continental origins. However, when these were weighted according to their frequency of occurrence, air with maritime origins made a greater contribution to annual mean concentrations.

  6. Effect of resistance training with elements of stretching on body composition and quality of life in postmenopausal women

    PubMed Central

    Frączak, Paulina; Jonak, Wiesława; Sobiech, Krzysztof A.

    2016-01-01

    Introduction Physical activity in elderly persons contributes to prevention and treatment of chronic disease and, through its influence on the musculoskeletal system, increases physical capability and improves mental function. Aim of the study Aim of the study was to assess the effect of resistance training with elements of stretching on body composition and quality of life in women of postmenopausal age. Material and methods Thirty-eight postmenopausal women aged 62.5 ±5.8 years were randomly divided into two groups. One group participated in an 8-week training program (60 minutes, twice weekly; 4 MET [metabolic equivalent] 2 hours/week). The second group performed no training. A comparison was made of body composition and quality of life (SF-36 Health Survey) prior to and after 8 weeks of training. Results In the training group, after 8 weeks there was a significant reduction in body fat (in%; p = 0.028), and an increase in fat-free mass (in%; p = 0.025) and total body water (in%; p = 0.021), which indicates increased muscle mass. Furthermore, there were statistically significant differences in the assessment of quality of life in physical (role-physical [RP], bodily pain [BP], general health [GH] scales; p < 0.005) and mental health (vitality [VT] scale; p = 0.05). In the non-exercising group no changes were observed in features examined in the initial and final test. Conclusions Resistance training with elements of stretching in postmenopausal women improved body composition to achieve a reduction in risk factors associated with excess fatty tissue and muscle mass deficiency. It raises the quality of life in terms of both physical and mental function. PMID:27095955

  7. Temporal Variations in the Abundance and Composition of Biofilm Communities Colonizing Drinking Water Distribution Pipes

    PubMed Central

    Kelly, John J.; Minalt, Nicole; Culotti, Alessandro; Pryor, Marsha; Packman, Aaron

    2014-01-01

    Pipes that transport drinking water through municipal drinking water distribution systems (DWDS) are challenging habitats for microorganisms. Distribution networks are dark, oligotrophic and contain disinfectants; yet microbes frequently form biofilms attached to interior surfaces of DWDS pipes. Relatively little is known about the species composition and ecology of these biofilms due to challenges associated with sample acquisition from actual DWDS. We report the analysis of biofilms from five pipe samples collected from the same region of a DWDS in Florida, USA, over an 18 month period between February 2011 and August 2012. The bacterial abundance and composition of biofilm communities within the pipes were analyzed by heterotrophic plate counts and tag pyrosequencing of 16S rRNA genes, respectively. Bacterial numbers varied significantly based on sampling date and were positively correlated with water temperature and the concentration of nitrate. However, there was no significant relationship between the concentration of disinfectant in the drinking water (monochloramine) and the abundance of bacteria within the biofilms. Pyrosequencing analysis identified a total of 677 operational taxonomic units (OTUs) (3% distance) within the biofilms but indicated that community diversity was low and varied between sampling dates. Biofilms were dominated by a few taxa, specifically Methylomonas, Acinetobacter, Mycobacterium, and Xanthomonadaceae, and the dominant taxa within the biofilms varied dramatically between sampling times. The drinking water characteristics most strongly correlated with bacterial community composition were concentrations of nitrate, ammonium, total chlorine and monochloramine, as well as alkalinity and hardness. Biofilms from the sampling date with the highest nitrate concentration were the most abundant and diverse and were dominated by Acinetobacter. PMID:24858562

  8. A detailed investigation of ambient aerosol composition and size distribution in an urban atmosphere.

    PubMed

    Kuzu, S Levent; Saral, Arslan; Demir, Selami; Summak, Gülsüm; Demir, Göksel

    2013-04-01

    This research was executed between March 2009 and March 2010 to monitor particulate matter size distribution and its composition in Istanbul. Particulate matter composition was determined using ion chromatography and inductively coupled plasma optical emission spectrometry. The sampling point is adjacent to a crowded road and the Bosporus Strait. Two prevailing particulate modes are found throughout PM10 by sampling with a nine-stage low-volume cascade impactor. First mode in the fine mode is found to be between 0.43 and 0.65 μm, whereas the other peak was observed between 3.3 and 4.7 μm, referring to the coarse mode. The mean PM10 concentration was determined as 41.2 μg/m(3), with a standard deviation of 16.92 μg/m(3). PM0.43 had the highest mean concentration value of 10.67 μg/m(3), making up nearly one fourth of the total PM10 mass. For determining the effect of traffic on particulate matter (PM) composition and distribution, four different sampling cycles were applied: entire day, nighttime, rush hour, and rush hour at weekdays. SO4(-2) and organic carbon/elemental carbon proportions are found to be lower in night samples, representing a decrease in traffic. The long-range transports of dust storms were observed during the sampling periods. Their effects were determined analytically and their route models were run by the HYSPLIT model and validated through satellite photographs taken by the NASA Earth Observatory. PMID:22968673

  9. Electrical Resistance of SiC/SiC Ceramic Matrix Composites for Damage Detection and Life-Prediction

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Morscher, Gregory; Xia, Zhenhai

    2009-01-01

    Ceramic matrix composites (CMC) are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems due to their low density high thermal conductivity. The employment of these materials in such applications is limited by the ability to accurately monitor and predict damage evolution. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. CMC is a multifunctional material in which the damage is coupled with the material s electrical resistance, providing the possibility of real-time information about the damage state through monitoring of resistance. Here, resistance measurement of SiC/SiC composites under mechanical load at both room temperature monotonic and high temperature creep conditions, coupled with a modal acoustic emission technique, can relate the effects of temperature, strain, matrix cracks, fiber breaks, and oxidation to the change in electrical resistance. A multiscale model can in turn be developed for life prediction of in-service composites, based on electrical resistance methods. Results of tensile mechanical testing of SiC/SiC composites at room and high temperatures will be discussed. Data relating electrical resistivity to composite constituent content, fiber architecture, temperature, matrix crack formation, and oxidation will be explained, along with progress in modeling such properties.

  10. A new decoupling method for accurate quantification of polyethylene copolymer composition and triad sequence distribution with 13C NMR.

    PubMed

    Zhou, Zhe; Kümmerle, Rainer; Qiu, Xiaohua; Redwine, David; Cong, Rongjuan; Taha, Angela; Baugh, Dan; Winniford, Bill

    2007-08-01

    (13)C NMR is a powerful analytical tool for characterizing polyethylene copolymer composition and sequence distribution. Accurate characterization of the composition and sequence distribution is critical for researchers in industry and academia. Some common composite pulse decoupling (CPD) sequences used in polyethylene copolymer (13)C NMR can lead to artifacts such as modulations of the decoupled (13)C NMR signals (decoupling sidebands) resulting in systematic errors in quantitative analysis. A new CPD method was developed, which suppresses decoupling sidebands below the limit of detection (less than 1:40,000 compared to the intensity of the decoupled signal). This new CPD sequence consists of an improved Waltz-16 CPD, implemented as a bilevel method. Compared with other conventional CPD programs this new decoupling method produced the cleanest (13)C NMR spectra for polyethylene copolymer composition and triad sequence distribution analyses. PMID:17524686

  11. Life Prediction Issues in Thermal/Environmental Barrier Coatings in Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Shah, Ashwin R.; Brewer, David N.; Murthy, Pappu L. N.

    2001-01-01

    Issues and design requirements for the environmental barrier coating (EBC)/thermal barrier coating (TBC) life that are general and those specific to the NASA Ultra-Efficient Engine Technology (UEET) development program have been described. The current state and trend of the research, methods in vogue related to the failure analysis, and long-term behavior and life prediction of EBCITBC systems are reported. Also, the perceived failure mechanisms, variables, and related uncertainties governing the EBCITBC system life are summarized. A combined heat transfer and structural analysis approach based on the oxidation kinetics using the Arrhenius theory is proposed to develop a life prediction model for the EBC/TBC systems. Stochastic process-based reliability approach that includes the physical variables such as gas pressure, temperature, velocity, moisture content, crack density, oxygen content, etc., is suggested. Benefits of the reliability-based approach are also discussed in the report.

  12. Effects of Temperature, Oxidation and Fiber Preforms on Fatigue Life of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-04-01

    In this paper, the effects of temperature, oxidation and fiber preforms on the fatigue life of carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) have been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S-N curves and fatigue limits of unidirectional, cross-ply, 2D, 2.5D and 3D C/SiC composites at room temperature, 800 °C in air, 1100, 1300 and 1500 °C in vacuum conditions have been predicted.

  13. [Floristic composition and distribution of the Andean subtropical riparian forests of Lules River, Tucuman, Argentina].

    PubMed

    Sirombra, Martín G; Mesa, Leticia M

    2010-03-01

    We studied the floristic composition and distribution of the riparian forest of two hydrographical systems in a subtropical Andean region. Using uni and multivariate techniques, we tested the hypotheses that a differentiable riparian forest exists, composed by native vegetation typical of the Yungas phytogeographical province, and that the distribution of vegetation varied significantly with geomorphologic characteristics. Parallel transects along the water courses were used to collect presence-absence data of vegetation in eleven sites. Detrended Correspondence Analysis defined a group of common riparian species for the studied area (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium and Eugenia uniflora) and identified two reference sites. The distribution of the riparian vegetation varied significantly with the geomorphic characteristics along the studied sites. Riparian habitats were composed by native and exotic species. A distinct riparian flora, different in structure and function from adjacent terrestrial vegetation, could not be identified. Riparian species were similar to the adjacent terrestrial strata. These species would not be limited by the proximity to the river. Anthropogenic impacts were important factors regulating the introduction and increase of exotic vegetation. The lack of regulation of some activities in the zone could cause serious problems in the integrity of this ecosystem. PMID:20411737

  14. Molecular Structures of Polymer/Sulfur Composites for Lithium-Sulfur Batteries with Long Cycle Life

    SciTech Connect

    Xiao, Lifen; Cao, Yuliang; Xiao, Jie; Schwenzer, Birgit; Engelhard, Mark H.; Saraf, Laxmikant V.; Nie, Zimin; Exarhos, Gregory J.; Liu, Jun

    2013-04-26

    Vulcanizedpolyaniline/sulfur (SPANI/S) nanostructures were investigated for Li-S battery applications, but the detailed molecular structures of such composites have not been fully illustrated. In this paper, we synthesize SPANI/S composites with different S content in a nanorod configuration. FTIR, Raman, XPS, XRD, SEM and elemental analysis methods are used to characterize the molecular structure of the materials. We provide clear evidence that a portion of S was grafted on PANI during heating and connected the PANI chains with disulfide bonds to form a crosslinked network and the rest of S was encapsulated within it.. Polysulfides and elementary sulfur nanoparticles are physically trapped inside the polymer network and are not chemically bound to the polymer. The performance of the composites is further improved by reducing the particle size. Even after 500 cycles a capacity retention rate of 68.8% is observed in the SPANI/S composite with 55% S content.

  15. Investigation on stress distribution of multilayered composite structure (MCS) using infrared thermographic technique

    NASA Astrophysics Data System (ADS)

    Liu, Junyan; Gong, Jinlong; Liu, Liqiang; Qin, Lei; Wang, Yang

    2013-11-01

    In this paper, the thermoelastic stress analysis (TSA) on a multilayered composite structure (MCS) was investigated by means of lock-in thermographic image technique (LITI). The application of thermoelastic stress analysis on MCS becomes particularly complicated due to consisting of different material components, which determines the different thermoelastic coupling response depended on material thermal-physical property. The thermoelastic coupling constants (TCC) of GFRP, medium-carbon steel and foam were obtained through thermomechanical calibration experiments, respectively. An artificial neural network was proposed to determine the component of MCS. Comparisons between finite element analysis (FEA) and LITI measurement are reported. It is found that the stress distribution of MCS can be evaluated with good accuracies using LITI measurement.

  16. Interfacial shear stress distribution in model composites. I - A Kevlar 49 fibre in an epoxy matrix

    SciTech Connect

    Jahankhani, H.; Galiotis, C. )

    1991-05-01

    The technique of Laser Raman Spectroscopy has been applied in the study of aramid fibers, such as Kevlar 49, and aramid/epoxy interfaces. A linear relationship has been found between Raman frequencies and strain upon loading a single Kevlar 49 filament in air. Model composites of single Kevlar 49 fibers embedded in epoxy resins have been fabricated and subjected to various degrees of mechanical deformation. The transfer lengths for reinforcement have been measured at various levels of applied tensile load and the dependence of transfer length upon applied matrix strain has been established. Finally, by balancing the tensile and the shear forces acting along the interface, the interfacial shear stress (ISS) distribution along the embedded fiber was obtained. 52 refs.

  17. Base composition and gene distribution: critical patterns in mammalian genome organization.

    PubMed

    Gardiner, K

    1996-12-01

    Recent success in developing transcriptional maps of large genomic regions provide excellent opportunities for the investigation of mammalian genome organization. Detailed definition of organizational features will, in the short term, aid in prioritizing genomic sequencing efforts and in interpreting sequencing results and, in the long term, will surely provide insights into the structural, functional and evolutionary basis for the mammalian chromosome and chromosomal banding patterns. For such efforts, human chromosome 21 provides an excellent model system because the physical and clone maps are detailed, and several transcriptional mapping projects have provided large numbers of novel genes. It is, therefore, valuable at this point to examine these transcriptional mapping data and to compare them with the isochore model of the mammalian genome, which describes patterns in base composition and predicts gene distributions. Not only do compelling organizational patterns appear, but new questions about additional possible patterns in gene size, structure, conservation and transcription can be asked. PMID:9257535

  18. Micromechanism based modeling of structural life in metal matrix composites. Final technical report, 1 June 1994--30 September 1997

    SciTech Connect

    Allen, D.H.; Lagoudas, D.C.

    1997-03-23

    This report details the most recent accomplishments that have lead towards the fulfillment of the grant objectives. These achievements include: (1) life prediction of continuous fiber metal matrix composites; (2) the influence of heat treatment on the mechanical properties and damage development in a SiC/Ti-15-3 MMC; (3) the experimental characterization of oxidation on fracture surfaces and crack growth behavior; (4) modeling the effects of oxidation on the crack growth resistance of metals; and (5) the modeling of oxidation fronts in metals. In summary, the development of a low-cycle life prediction model that has the capability to account for the effect of surface oxidation on life of titanium matrix MMC`s is complete. The research performed herein concluded that the life of the composite appears to be controlled by interface debonding and subsequent radial cracking. The work performed under this grant also included a program to experimentally characterize the morphology of TiO{sub 2}, one of the primary stoichiometric oxides formed during oxidation of titanium, in order to develop more accurate oxide layer growth models. It has been shown that specimen geometry plays a significant role in the rate of oxide growth. The last phase of this research effort was to develop and numerically implement a mathematical model of oxidation for metals with the capability of modeling complex oxidation fronts, such as they arise in MMC`s. The oxidation of metals has been modeled by modifying the Fickian diffusion problem in order to simulate the chemical reaction (phase change) in the metal. The current model is capable of solving 1D and 2D oxidation problems in metallic domains with complex geometry.

  19. Investigation of chloride induced corrosion of bridge pier and life-cycle repair cost analysis using fiber reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Dhakal, Dinesh

    Bridges are the long term investment of the highway agencies. To maintain the required service level throughout the life of a bridge, a series of maintenance, repair, and rehabilitation (MRℝ) works can be performed. To investigate the corrosion deterioration and maintenance and repair practices in the bridge pier columns constructed in chloride-laden environment, a questionnaire survey was conducted within the 50 state Departments of Transportation (DOTs). Based on the survey data, two corrosion deterioration phases were identified. They were corrosion crack initiation phase and corrosion propagation phase. The data showed that the mean corrosion crack initiation phase for bridge pier column having cover of 50 mm, 75 mm, and 100 mm was 18.9 years, 20.3 years, and 22.5 years, respectively. The corrosion propagation phase starts after the corrosion crack initiation. The corrosion propagation is defined in a single term, corrosion damage rate, measured as percentage of area damaged due to corrosion cracking, spalling, and delamination. From the survey, the corrosion damage rate was found 2.23% and 2.10% in the bridge pier columns exposed to deicing salt water and exposed to tidal splash/spray, respectively. For this study, two different corrosion damage rates were proposed before and after the repair criteria for minor damage repair as practiced by DOTs. This study also presents the collected data regarding the corrosion effectiveness of using sealers and coatings, cathodic protection, corrosion inhibitors, carbon fiber/epoxy composites, and glass fiber/epoxy composites as maintenance and repair technique. In this study, the cost-effectiveness of wrapping carbon fiber/epoxy composites and glass fiber/epoxy composites in bridge pier columns constructed in a chloride-laden environment was investigated by conducting life-cycle cost analysis. As a repair work, externally bonded two layer of carbon fiber/epoxy and glass fiber/epoxy composites were installed by wet-layup method in full height of the bridge pier column stem. The damaged concrete surface was completely repaired before installing external wraps. Three different strategies were defined based on the consideration of the first FRP repair at three different corrosion deterioration phases. The strategies were to apply FRP as preventive maintenance during corrosion initiation period, to apply FRP during the corrosion damage propagation, and to apply FRP after major damage. For both composites, the strategy to repair bridge pier column at early stage of corrosion damage, which is at the age of 25 year, was observed optimum, and the use of glass fiber composite wraps resulted in lower total life-cycle repair cost. The use of carbon fiber composites in repair found to have lower total life-cycle repair cost for lower discount rate up to 6% when repair is considered at the age of 15 to 20 years.

  20. Development of a fatigue-life methodology for composite structures subjected to out-of-plane load components

    NASA Technical Reports Server (NTRS)

    Sumich, Mark; Kedward, Keith T.

    1991-01-01

    The efforts to identify and implement a fatigue life methodology applicable to demonstrate delamination failures for use in certifying composite rotor blades are presented. The RSRA/X-Wing vehicle was a proof-of-concept stopped rotor aircraft configuration which used rotor blades primarily constructed of laminated carbon fiber. Delamination of the main spar during ground testing demonstrated that significant interlaminar stresses were produced. Analysis confirmed the presence of out-of-plane load components. The wear out (residual strength) methodology and the requirements for its implementation are discussed.

  1. A study of stiffness, residual strength and fatigue life relationships for composite laminates

    NASA Technical Reports Server (NTRS)

    Ryder, J. T.; Crossman, F. W.

    1983-01-01

    Qualitative and quantitative exploration of the relationship between stiffness, strength, fatigue life, residual strength, and damage of unnotched, graphite/epoxy laminates subjected to tension loading. Clarification of the mechanics of the tension loading is intended to explain previous contradictory observations and hypotheses; to develop a simple procedure to anticipate strength, fatigue life, and stiffness changes; and to provide reasons for the study of more complex cases of compression, notches, and spectrum fatigue loading. Mathematical models are developed based upon analysis of the damage states. Mathematical models were based on laminate analysis, free body type modeling or a strain energy release rate. Enough understanding of the tension loaded case is developed to allow development of a proposed, simple procedure for calculating strain to failure, stiffness, strength, data scatter, and shape of the stress-life curve for unnotched laminates subjected to tension load.

  2. The bacteriological composition of biomass recovered by flushing an operational drinking water distribution system.

    PubMed

    Douterelo, I; Husband, S; Boxall, J B

    2014-05-01

    This study investigates the influence of pipe characteristics on the bacteriological composition of material mobilised from a drinking water distribution system (DWDS) and the impact of biofilm removal on water quality. Hydrants in a single UK Distribution Management Area (DMA) with both polyethylene and cast iron pipe sections were subjected to incremental increases in flow to mobilise material from the pipe walls. Turbidity was monitored during these operations and water samples were collected for physico-chemical and bacteriological analysis. DNA was extracted from the material mobilised into the bulk water before and during flushing. Bacterial tag-encoded 454 pyrosequencing was then used to characterize the bacterial communities present in this material. Turbidity values were high in the samples from cast iron pipes. Iron, aluminium, manganese and phosphate concentrations were found to correlate to observed turbidity. The bacterial community composition of the material mobilised from the pipes was significantly different between plastic and cast iron pipe sections (p < 0.5). High relative abundances of Alphaproteobacteria (23.3%), Clostridia (10.3%) and Actinobacteria (10.3%) were detected in the material removed from plastic pipes. Sequences related to Alphaproteobacteria (22.8%), Bacilli (16.6%), and Gammaproteobacteria (1.4%) were predominant in the samples obtained from cast iron pipes. The highest species richness and diversity were found in the samples from material mobilised from plastic pipes. Spirochaeta spp., Methylobacterium spp. Clostridium spp. and Desulfobacterium spp., were the most represented genera in the material obtained prior to and during the flushing of the plastic pipes. In cast iron pipes a high relative abundance of bacteria able to utilise different iron and manganese compounds were found such as Lysinibacillus spp., Geobacillus spp. and Magnetobacterium spp. PMID:24565801

  3. Decompression vs. Decomposition: Distribution, Amount, and Gas Composition of Bubbles in Stranded Marine Mammals

    PubMed Central

    de Quirós, Yara Bernaldo; González-Diaz, Oscar; Arbelo, Manuel; Sierra, Eva; Sacchini, Simona; Fernández, Antonio

    2012-01-01

    Gas embolic lesions linked to military sonar have been described in stranded cetaceans including beaked whales. These descriptions suggest that gas bubbles in marine mammal tissues may be more common than previously thought. In this study we have analyzed gas amount (by gas score) and gas composition within different decomposition codes using a standardized methodology. This broad study has allowed us to explore species-specific variability in bubble prevalence, amount, distribution, and composition, as well as masking of bubble content by putrefaction gases. Bubbles detected within the cardiovascular system and other tissues related to both pre- and port-mortem processes are a common finding on necropsy of stranded cetaceans. To minimize masking by putrefaction gases, necropsy, and gas sampling must be performed as soon as possible. Before 24 h post mortem is recommended but preferably within 12 h post mortem. At necropsy, amount of bubbles (gas score) in decomposition code 2 in stranded cetaceans was found to be more important than merely presence vs. absence of bubbles from a pathological point of view. Deep divers presented higher abundance of gas bubbles, mainly composed of 70% nitrogen and 30% CO2, suggesting a higher predisposition of these species to suffer from decompression-related gas embolism. PMID:22675306

  4. Temperature Distribution in a Composite of Opaque and Semitransparent Spectral Layers

    NASA Technical Reports Server (NTRS)

    Siegel, Robert

    1997-01-01

    The analysis of radiative transfer becomes computationally complex for a composite when there are multiple layers and multiple spectral bands. A convenient analytical method is developed for combined radiation and conduction in a composite of alternating semitransparent and opaque layers. The semi- transparent layers absorb, scatter, and emit radiation, and spectral properties with large scattering are included. The two-flux method is used, and its applicability is verified by comparison with a basic solution in the literature. The differential equation in the two-flux method Is solved by deriving a Green's function. The solution technique is applied to analyze radiation effects in a multilayer zirconia thermal barrier coating with internal radiation shields for conditions in an aircraft engine combustor. The zirconia radiative properties are modeled by two spectral bands. Thin opaque layers within the coating are used to decrease radiant transmission that can degrade the zirconia insulating ability. With radiation shields, the temperature distributions more closely approach the opaque limit that provides the lowest metal wall temperatures.

  5. Processing and Characterization of a Novel Distributed Strain Sensor Using Carbon Nanotube-Based Nonwoven Composites

    PubMed Central

    Dai, Hongbo; Thostenson, Erik T.; Schumacher, Thomas

    2015-01-01

    This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM). This novel strain sensor is fabricated using a readily scalable process of coating Carbon nanotubes (CNT) onto a nonwoven carrier fabric to form an electrically-isotropic conductive network. Epoxy is then infused into the CNT-modified fabric to form a free-standing nanocomposite strain sensor. By measuring the changes in the electrical properties of the sensing composite the deformation can be measured in real-time. The sensors are repeatable and linear up to 0.4% strain. Highest elastic strain gage factors of 1.9 and 4.0 have been achieved in the longitudinal and transverse direction, respectively. Although the longitudinal gage factor of the newly formed nanocomposite sensor is close to some metallic foil strain gages, the proposed sensing methodology offers spatial coverage, manufacturing customizability, distributed sensing capability as well as transverse sensitivity. PMID:26197323

  6. Processing and Characterization of a Novel Distributed Strain Sensor Using Carbon Nanotube-Based Nonwoven Composites.

    PubMed

    Dai, Hongbo; Thostenson, Erik T; Schumacher, Thomas

    2015-01-01

    This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM). This novel strain sensor is fabricated using a readily scalable process of coating Carbon nanotubes (CNT) onto a nonwoven carrier fabric to form an electrically-isotropic conductive network. Epoxy is then infused into the CNT-modified fabric to form a free-standing nanocomposite strain sensor. By measuring the changes in the electrical properties of the sensing composite the deformation can be measured in real-time. The sensors are repeatable and linear up to 0.4% strain. Highest elastic strain gage factors of 1.9 and 4.0 have been achieved in the longitudinal and transverse direction, respectively. Although the longitudinal gage factor of the newly formed nanocomposite sensor is close to some metallic foil strain gages, the proposed sensing methodology offers spatial coverage, manufacturing customizability, distributed sensing capability as well as transverse sensitivity. PMID:26197323

  7. [Characteristics of distribution and composition of organic carbon in Dongting Lake floodplain].

    PubMed

    Zhang, Wen-ju; Peng, Pei-qin; Tong, Cheng-li; Wang, Xiao-li; Wu, Jin-shui

    2005-05-01

    Distribution and composition of organic carbon (OC) at nine soil profiles of three types of wetlands in Dongting Lake floodplain were analyzed. Results show that the OC content at top layer (0-10 cm) in Carex spp-dominated floodplain was much higher (>40 g/kg) than that in Phragmites-dominated floodplain (20 +/- 2.8) g/kg and paddy soil (28 +/- 8.6) g/kg. The OC content decreased with increasing depth from 0 to 30 cm, while it was relatively stable (around 15 g/kg) at depths deeper than 30 cm in Carex spp-dominated and Phragmites-dominated floodplain. However, there was a substantial variability in OC content in paddy soil profiles. In terms of the composition of OC, at top layer (0-10 cm), light fraction carbon in Carex spp-dominated floodplain accounted for more than 20% of the total organic carbon, whereas more than 90% of total organic carbon were heavy fraction that were much more difficult to be decomposed in Phragmites-dominated floodplain and paddy soils. The ratio of light fraction to total organic carbon at the soil profiles was greatly affected by the origin of organic matter. Statistical analyses indicate that there were significant correlations between heavy fraction and total organic carbon, between bulk density and total organic carbon, and between OC and nitrogen in heavy fraction (p<0.01). PMID:16124470

  8. Decompression vs. Decomposition: Distribution, Amount, and Gas Composition of Bubbles in Stranded Marine Mammals.

    PubMed

    de Quirós, Yara Bernaldo; González-Diaz, Oscar; Arbelo, Manuel; Sierra, Eva; Sacchini, Simona; Fernández, Antonio

    2012-01-01

    Gas embolic lesions linked to military sonar have been described in stranded cetaceans including beaked whales. These descriptions suggest that gas bubbles in marine mammal tissues may be more common than previously thought. In this study we have analyzed gas amount (by gas score) and gas composition within different decomposition codes using a standardized methodology. This broad study has allowed us to explore species-specific variability in bubble prevalence, amount, distribution, and composition, as well as masking of bubble content by putrefaction gases. Bubbles detected within the cardiovascular system and other tissues related to both pre- and port-mortem processes are a common finding on necropsy of stranded cetaceans. To minimize masking by putrefaction gases, necropsy, and gas sampling must be performed as soon as possible. Before 24 h post mortem is recommended but preferably within 12 h post mortem. At necropsy, amount of bubbles (gas score) in decomposition code 2 in stranded cetaceans was found to be more important than merely presence vs. absence of bubbles from a pathological point of view. Deep divers presented higher abundance of gas bubbles, mainly composed of 70% nitrogen and 30% CO(2), suggesting a higher predisposition of these species to suffer from decompression-related gas embolism. PMID:22675306

  9. Tracing subsoil organic matter compositional changes by radiocarbon and plant leaf wax distributional changes

    NASA Astrophysics Data System (ADS)

    John, Stephan; Angst, Gerrit; Mueller, Carsten W.; Heinze, Stefanie; Marschner, Bernd; Rethemeyer, Janet

    2014-05-01

    The carbon pool in subsoils is thought to be considerably larger than in the upper 30 cm. However, factors like turnover, stabilization and distribution of organic matter (OM) are less well understood than in topsoils. The investigation of changes in OM composition with depth enables a better understanding of the peculiarity of subsoil OM in contrast to the already extensively studied topsoil OM. Analysis of long chained n-alkanes and n-fatty acids in soil profiles sampled in high resolution, combined with radiocarbon data of bulk soil, is a tool to demonstrate spatial distribution and the degradation of plant leaf wax-derived material as a defined source of soil organic. We analysed the OM in 3.15 m long soil transects under an even aged European beech (Fagus sylvatica L.) forest in Northern Germany (Grinderwald, Lower Saxony) for lipid and radiocarbon analysis. Samples were taken from a grid raster with eight sampling points increasing in distance to the main tree (45cm grid dimension) and from five depths (10, 35, 60, 85, 110 cm) resulting 40 samples per transect. Organic carbon contents in the podzolic Cambisol decrease from 1.69 % in the A-horizon to 0.02 % in the C-horizon at 110 cm depth. The distribution of organic carbon contents shows no significant trend with increasing distance to the beeches in all transects. We compare the distribution of long-chain n-alkanes (C27, C29 and C31) and n-fatty acids (>C20), known as components mainly derived from leaf waxes of higher plants, in the different transect/depth intervals. Distributional and quantitative changes in the transects, combined with bulk soil 14C-analyses, reflecting apparent mean residence time of OM, are used to identify how fast OM is degraded from surface to subsoil horizons. Furthermore, spatial OM heterogeneity in the transects is investigated. We expect a more significant heterogeneity in the lipid distribution and nearly similar decreasing contents for n-alkanes as well as n-fatty acids. Furthermore, the comparison between these two compound classes with increasing depth gives information on the accumulation of more resistant (aliphatic) and more easily degradable (carboxylic acids) OM components.

  10. Comparative life cycle studies on poly(3-hydroxybutyrate)-based composites as potential replacement for conventional petrochemical plastics.

    PubMed

    Pietrini, Matteo; Roes, Lex; Patel, Martin K; Chiellini, Emo

    2007-07-01

    A cradle-to-grave environmental life cycle assessment (LCA) of a few poly(3-hydroxybutyrate) (PHB) based composites has been performed and was compared to commodity petrochemical polymers. The end products studied are a cathode ray tube (CRT) monitor housing (conventionally produced from high-impact polystyrene, HIPS) and the internal panels of an average car (conventionally produced from glass-fibers-filled polypropylene, PP-GF). The environmental impact is evaluated on the basis of nonrenewable energy use (NREU) and global warming potential over a 100 years time horizon (GWP100). Sugar cane bagasse (SCB) and nanoscaled organophilic montmorillonite (OMMT) are used as PHB fillers. The results obtained show that, despite the unsatisfying mechanical properties of PHB composites, depending on the type of filler and on the product, it is possible to reach lower environmental impacts than by use of conventional petrochemical polymers. These savings are mainly related to the PHB production process, while there are no improvements related to composites preparation. SCB-based composites seem to be environmentally superior to clay-based ones. PMID:17583946

  11. Using and Distributing Spaceflight Data: The Johnson Space Center Life Sciences Data Archive

    NASA Technical Reports Server (NTRS)

    Cardenas, J. A.; Buckey, J. C.; Turner, J. N.; White, T. S.; Havelka,J. A.

    1995-01-01

    Life sciences data collected before, during and after spaceflight are valuable and often irreplaceable. The Johnson Space Center Life is hard to find, and much of the data (e.g. Sciences Data Archive has been designed to provide researchers, engineers, managers and educators interactive access to information about and data from human spaceflight experiments. The archive system consists of a Data Acquisition System, Database Management System, CD-ROM Mastering System and Catalog Information System (CIS). The catalog information system is the heart of the archive. The CIS provides detailed experiment descriptions (both written and as QuickTime movies), hardware descriptions, hardware images, documents, and data. An initial evaluation of the archive at a scientific meeting showed that 88% of those who evaluated the catalog want to use the system when completed. The majority of the evaluators found the archive flexible, satisfying and easy to use. We conclude that the data archive effectively provides key life sciences data to interested users.

  12. Application of Distribution Transformer Thermal Life Models to Electrified Vehicle Charging Loads Using Monte-Carlo Method: Preprint

    SciTech Connect

    Kuss, M.; Markel, T.; Kramer, W.

    2011-01-01

    Concentrated purchasing patterns of plug-in vehicles may result in localized distribution transformer overload scenarios. Prolonged periods of transformer overloading causes service life decrements, and in worst-case scenarios, results in tripped thermal relays and residential service outages. This analysis will review distribution transformer load models developed in the IEC 60076 standard, and apply the model to a neighborhood with plug-in hybrids. Residential distribution transformers are sized such that night-time cooling provides thermal recovery from heavy load conditions during the daytime utility peak. It is expected that PHEVs will primarily be charged at night in a residential setting. If not managed properly, some distribution transformers could become overloaded, leading to a reduction in transformer life expectancy, thus increasing costs to utilities and consumers. A Monte-Carlo scheme simulated each day of the year, evaluating 100 load scenarios as it swept through the following variables: number of vehicle per transformer, transformer size, and charging rate. A general method for determining expected transformer aging rate will be developed, based on the energy needs of plug-in vehicles loading a residential transformer.

  13. Body composition of infants fed breast-milk, milk-based formula or soy-based formula during the first 6 months of life

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Literature on the impact of infant feeding on body composition is sparse and inconclusive. We assessed body composition in infants exclusively fed breast-milk (BF), milk-based formula (MF) or soy-based formula (SF) for at least the first 4 months of life. Participants are part of the on-going prosp...

  14. Bumble Bees (Hymenoptera: Apidae: Bombus spp.) of Interior Alaska: Species Composition, Distribution, Seasonal Biology, and Parasites

    PubMed Central

    Pampell, Rehanon; Pantoja, Alberto; Holloway, Patricia; Knight, Charles; Ranft, Richard

    2015-01-01

    Abstract Background Despite the ecological and agricultural significance of bumble bees in Alaska, very little is known and published about this important group at the regional level. The objectives of this study were to provide baseline data on species composition, distribution, seasonal biology, and parasites of the genus Bombus at three major agricultural locations within Alaska: Fairbanks, Delta Junction, and Palmer, to lay the groundwork for future research on bumble bee pollination in Alaska. New information A total of 8,250 bumble bees representing 18 species was collected from agricultural settings near Delta Junction, Fairbanks, and Palmer, Alaska in 2009 and 2010. Of the 8,250 specimens, 51% were queens, 32.7% were workers, and 16.2% were males. The species composition and relative abundances varied among sites and years. Delta Junction had the highest relative abundance of bumble bees, representing 51.6% of the specimens collected; the other two locations, Fairbanks and Palmer represented 26.5% and 21.8% of the overall catch respectively. The species collected were: Bombus bohemicus Seidl 1837 (= B. ashtoni (Cresson 1864)), B. balteatus Dahlbom 1832, B. bifarius Cresson 1878, B. centralis Cresson 1864, B. cryptarum (Fabricius 1775) (=B. moderatus Cresson 1863), B. distinguendus Morawitz 1869, B. flavidus Eversmann 1852 (=B. fernaldae Franklin 1911), B. flavifrons Cresson 1863, B. frigidus Smith 1854, B. insularis (Smith 1861), B. jonellus (Kirby 1802), B. melanopygus Nylander 1848, B. mixtus Cresson 1878, B. neoboreus Sladen 1919, B. occidentalis Greene 1858, B. perplexus Cresson 1863, B. rufocinctus Cresson 1863, and B. sylvicola Kirby 1837. Overall, the most common bumble bees near agricultural lands were B. centralis, B. frigidus, B. jonellus, B. melanopygus, B. mixtus, and B. occidentalis. Species' relative population densities and local diversity were highly variable from year to year. Bombus occidentalis, believed to be in decline in the Pacific Northwest states, represented 10.4% of the overall specimens collected from the three sites studied. Bumble bees were found to be infected by Nosema and nematodes with infection rates up to 2.1% and 16.7% respectively. Of the eight species infected by parasites, B. occidentalis displayed the highest Nosema infection, while B. centralis was the species with the highest infection of nematodes. To our knowledge this represents the first multi-year study on bumble bees from the main agricultural areas of Alaska to provide baseline data on species composition, distribution, seasonal biology, and parasites of the genus Bombus. PMID:25977613

  15. Transverse Tension Fatigue Life Characterization Through Flexure Testing of Composite Materials

    NASA Technical Reports Server (NTRS)

    OBrien, T. Kevin; Chawan, Arun D.; Krueger, Ronald; Paris, Isabelle

    2001-01-01

    The transverse tension fatigue life of S2/8552 glass-epoxy and IM7/8552 carbon-epoxy was characterized using flexure tests of 90-degree laminates loaded in 3-point and 4-point bending. The influence of specimen polishing and specimen configuration on transverse tension fatigue life was examined using the glass-epoxy laminates. Results showed that 90-degree bend specimens with polished machined edges and polished tension-side surfaces, where bending failures where observed, had lower fatigue lives than unpolished specimens when cyclically loaded at equal stress levels. The influence of specimen thickness and the utility of a Weibull scaling law was examined using the carbon-epoxy laminates. The influence of test frequency on fatigue results was also documented for the 4-point bending configuration. A Weibull scaling law was used to predict the 4-point bending fatigue lives from the 3-point bending curve fit and vice-versa. Scaling was performed based on maximum cyclic stress level as well as fatigue life. The scaling laws based on stress level shifted the curve fit S-N characterizations in the desired direction, however, the magnitude of the shift was not adequate to accurately predict the fatigue lives. Furthermore, the scaling law based on fatigue life shifted the curve fit S-N characterizations in the opposite direction from measured values. Therefore, these scaling laws were not adequate for obtaining accurate predictions of the transverse tension fatigue lives.

  16. Improved modeling of the percolation behavior of conductor-insulator composites with modulated granular size distributions

    NASA Astrophysics Data System (ADS)

    Shida, Kazuhito; Sahara, Ryoji; Tripathi, Madhvendra; Mizuseki, Hiroshi; Kawazoe, Yoshiyuki

    2010-03-01

    The percolation threshold shows a universality that may cause a strict limit on the mixture ratio of composite materials. When particles A and B are randomly filling a material and A must form an interconnected cluster (e.g. for electrical conduction), there is a strict limit on the fraction of A (for example, 0.598 in 2D). A solution to solve this problem is introducing size distribution on B particles (N.Lebovka J.Phys.D (2006) and WJ Kim J.Appl.Phys (1998)). However, theoretical understanding of this phenomenon is still in a quite immature stage despite of its importance in applications. We report the reduction of the percolation threshold observed in square lattices with a number of binary size distributions, as well as our approach toward semi-empirical theoretical method, that is based on an enumeration of local particle configurations generated in a totally random manner. This is a notable advance because most of previous theoretical methods were considering only limited combination of configurations, in which the positions of the B particles are not fully randomized.

  17. Vegetation in Bangalore's Slums: Composition, Species Distribution, Density, Diversity, and History

    NASA Astrophysics Data System (ADS)

    Gopal, Divya; Nagendra, Harini; Manthey, Michael

    2015-06-01

    There is widespread acknowledgement of the need for biodiversity and greening to be part of urban sustainability efforts. Yet we know little about greenery in the context of urban poverty, particularly in slums, which constitute a significant challenge for inclusive development in many rapidly growing cities. We assessed the composition, density, diversity, and species distribution of vegetation in 44 slums of Bangalore, India, comparing these to published studies on vegetation diversity in other land-use categories. Most trees were native to the region, as compared to other land-use categories such as parks and streets which are dominated by introduced species. Of the most frequently encountered tree species, Moringa oleifera and Cocos nucifera are important for food, while Ficus religiosa plays a critical cultural and religious role. Tree density and diversity were much lower in slums compared to richer residential neighborhoods. There are also differences in species preferences, with most plant (herb, shrub and vines) species in slums having economic, food, medicinal, or cultural use, while the species planted in richer residential areas are largely ornamental. Historic development has had an impact on species distribution, with older slums having larger sized tree species, while recent slums were dominated by smaller sized tree species with greater economic and food use. Extensive focus on planting trees and plant species with utility value is required in these congested neighborhoods, to provide livelihood support.

  18. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions

    DOEpatents

    Mrazek, Franklin C.; Smaga, John A.; Battles, James E.

    1983-01-01

    A positive electrode for a secondary electrochemical cell wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

  19. Simulating the size distribution and chemical composition of ultrafine particles during nucleation events

    NASA Astrophysics Data System (ADS)

    Jung, JaeGun; Adams, Peter J.; Pandis, Spyros N.

    We describe the development and evaluation of a computationally efficient new multicomponent aerosol dynamics model that simulates the full aerosol size distribution and composition starting at a diameter of 0.8 nm. The model uses a recently developed ternary (sulfuric acid-ammonia-water) nucleation parameterization and a two-moment sectional algorithm, simulating both the aerosol number and mass distributions. Three chemical components, sulfate, ammonium, and non-volatile organics are simulated. The model is evaluated first against analytical solutions of the coagulation and condensation equations and then against ambient measurements from the Pittsburgh Air Quality Study. The model is able to reproduce nucleation events from their start to completion. The simulations suggest that ammonia availability controls the nucleation bursts in the northeastern US. The first stage of the nucleation event in that area is the nucleation burst with growth of neutral ultrafine particles. In a second stage, the gas phase ammonia concentration approaches zero, the nucleation burst stops and the ultrafine particles become acidic growing by condensation of sulfuric acid. The present model is thirty times faster than comparable high-resolution models of aerosol dynamics and nucleation.

  20. Vegetation in Bangalore's Slums: Composition, Species Distribution, Density, Diversity, and History.

    PubMed

    Gopal, Divya; Nagendra, Harini; Manthey, Michael

    2015-06-01

    There is widespread acknowledgement of the need for biodiversity and greening to be part of urban sustainability efforts. Yet we know little about greenery in the context of urban poverty, particularly in slums, which constitute a significant challenge for inclusive development in many rapidly growing cities. We assessed the composition, density, diversity, and species distribution of vegetation in 44 slums of Bangalore, India, comparing these to published studies on vegetation diversity in other land-use categories. Most trees were native to the region, as compared to other land-use categories such as parks and streets which are dominated by introduced species. Of the most frequently encountered tree species, Moringa oleifera and Cocos nucifera are important for food, while Ficus religiosa plays a critical cultural and religious role. Tree density and diversity were much lower in slums compared to richer residential neighborhoods. There are also differences in species preferences, with most plant (herb, shrub and vines) species in slums having economic, food, medicinal, or cultural use, while the species planted in richer residential areas are largely ornamental. Historic development has had an impact on species distribution, with older slums having larger sized tree species, while recent slums were dominated by smaller sized tree species with greater economic and food use. Extensive focus on planting trees and plant species with utility value is required in these congested neighborhoods, to provide livelihood support. PMID:25840697

  1. Distribution of volatile composition in 'marion' ( rubus species hyb) blackberry pedigree.

    PubMed

    Du, Xiaofen; Finn, Chad; Qian, Michael C

    2010-02-10

    The distribution of volatile constituents in ancestral genotypes of 'Marion' blackberry's pedigree was investigated over two growing seasons. Each genotype in the pedigree had a specific volatile composition. Red raspberry was dominated by norisoprenoids, lactones, and acids. 'Logan' and 'Olallie' also had a norisoprenoid dominance but at much lower concentrations. The concentration of norisoprenoids in other blackberry genotypes was significantly lower. Terpenes and furanones were predominant in wild 'Himalaya' blackberry, whereas terpenes were the major volatiles in 'Santiam'. 'Marion', a selection from 'Chehalem' and 'Olallie', contained almost all of the volatile compounds in its pedigree at moderate amount. The chiral isomeric ratios of 11 pairs of compounds were also studied. Strong chiral isomeric preference was observed for most of the chiral compounds, and each cultivar had its unique chiral isomeric distribution. An inherent pattern was observed for some volatile compounds in the 'Marion' pedigree. Raspberry and 'Logan' had a very high concentration of beta-ionone, but was reduced by half in 'Olallie' and by another half in 'Marion' as the crossing proceeded. A high content of linalool in 'Olallie' and a low content in 'Chehalem' resulted in a moderate content of linalool in their progeny 'Marion'. However, the concentration of furaneol in 'Marion' was higher than in its parents. A high content of (S)-linalool in 'Olallie' and a racemic content of (S)-,(R)-linalool in 'Chehalem' resulted in a preference for the (S)-form in 'Marion'. PMID:20055446

  2. Research on the Composition and Distribution of Organic Sulfur in Coal.

    PubMed

    Zhang, Lanjun; Li, Zenghua; Yang, Yongliang; Zhou, Yinbo; Li, Jinhu; Si, Leilei; Kong, Biao

    2016-01-01

    The structure and distribution of organic sulfur in coals of different rank and different sulfur content were studied by combining mild organic solvent extraction with XPS technology. The XPS results have shown that the distribution of organic sulfur in coal is related to the degree of metamorphism of coal. Namely, thiophenic sulfur content is reduced with decreasing metamorphic degree; sulfonic acid content rises with decreasing metamorphic degree; the contents of sulfate sulfur, sulfoxide and sulfone are rarely related with metamorphic degree. The solvent extraction and GC/MS test results have also shown that the composition and structure of free and soluble organic sulfur small molecules in coal is closely related to the metamorphic degree of coal. The free organic sulfur small molecules in coal of low metamorphic degree are mainly composed of aliphatic sulfides, while those in coal of medium and high metamorphic degree are mainly composed of thiophenes. Besides, the degree of aromatization of organic sulfur small molecules rises with increasing degree of coalification. PMID:27187339

  3. Supporting Distributed Team Working in 3D Virtual Worlds: A Case Study in Second Life

    ERIC Educational Resources Information Center

    Minocha, Shailey; Morse, David R.

    2010-01-01

    Purpose: The purpose of this paper is to report on a study into how a three-dimensional (3D) virtual world (Second Life) can facilitate socialisation and team working among students working on a team project at a distance. This models the situation in many commercial sectors where work is increasingly being conducted across time zones and between

  4. Supporting Distributed Team Working in 3D Virtual Worlds: A Case Study in Second Life

    ERIC Educational Resources Information Center

    Minocha, Shailey; Morse, David R.

    2010-01-01

    Purpose: The purpose of this paper is to report on a study into how a three-dimensional (3D) virtual world (Second Life) can facilitate socialisation and team working among students working on a team project at a distance. This models the situation in many commercial sectors where work is increasingly being conducted across time zones and between…

  5. Composition and spatial distribution of volatile deposits in Loki Patera, Io

    NASA Astrophysics Data System (ADS)

    Landis, Claire E.

    Loki Patera is an active volcanic feature on Jupiter's moon Io which, at approximately 200 km in diameter, is perhaps the largest active lava lake in the solar system. Several images taken by the narrow angle camera of Voyager 1 during its 1979 flyby of Io reveal the patera surface is populated with many bright features roughly 2 to 4 km in diameter, colloquially referred to as "bergs." The bergs may be gas vents, similar to terrestrial fumaroles, which allow the sulfur-rich volatiles in the lava beneath the solid patera crust to escape and deposit on the surface. This thesis examines the spatial distribution of the bergs and their spectral signature in comparison with other features in the Loki region. The spectral analysis specifically focuses on the brightness in the blue and violet filters in an attempt to determine their composition and better understand how the bergs are related to the volcanic activity observed at Loki. The spatial distribution analysis reveals that the bergs are not randomly distributed across the patera surface and they avoid the inner and outer margins of the patera. There are no bergs within 4.96 km of the outer margin and only one berg occurs closer than 4.02 km to the inner margin. The bergs also avoid each other; bergs are on average 5.34 km from each other, and there is little deviation from this mean aside from the bergs in the southwest corner, which are spaced further apart. This corner has fewer bergs than elsewhere in the patera and is the site of the most volcanic activity. Data from the Voyager and Galileo missions were included in the spectral analyses. Assuming a macroscopic mixture, the spectral signature of the bergs indicate compositions ranging from bare basalt in the southwestern portion of the patera to approximately 43% sulfur and 57% basalt for the bergs. Other features around Loki, such as the large island in the middle of the patera, have slightly different brightnesses in the blue and violet filters which may indicate the presence of some SO 2 in addition to sulfur. There is evidence that a few of the largest bergs were not resurfaced between the Voyager and Galileo observations, suggesting some bergs may be fixed features. The bergs may be sulfur volatiles deposited on top of large mounds in the patera which could form during resurfacing events. One type of terrestrial lava mound, tumuli, typically have a linear crack running along the axis of the mound. If the bergs are a much larger version of tumuli seen on Earth, the axial fissure could provide a route for volatiles beneath the crust to escape onto the surface and deposit around the opening.

  6. MinSORTING: an Excel macro for modelling sediment composition and grain-size distribution

    NASA Astrophysics Data System (ADS)

    Resentini, Alberto; Malusà, Marco G.; Garzanti, Eduardo

    2013-04-01

    Detrital mineral analyses are gaining increasing attention in the geosciences as new single-grain analytical techniques are constantly improving their resolution, and consequently widening their range of application, including sedimentary petrology, tectonic geomorphology and archaeology (Mange and Wright, 2007; von Eynatten and Dunkl, 2012). We present here MinSORTING, a new tool to quickly predict the size distribution of various minerals and rock fragments in detrital sediments, based on the physical laws that control sedimentation by tractive wind or water currents (Garzanti et al., 2008). The input values requested by the software are the sediment mean size, sorting, fluid type (seawater, freshwater, air) and standard sediment composition chosen from a given array including nine diverse tectonic settings. MinSORTING calculates the bulk sediment density and the settling velocity. The mean size of each single detrital component, assumed as lognormally-distributed, is calculated from its characteristic size-shift with respect to bulk sediment mean size, dependent in turn on its density and shape. The final output of MinSORTING is the distribution of each single detrital mineral in each size classes (at the chosen 0.25, 0.5 or 1 phi intervals). This allows geochronolgists to select the most suitable grain size of sediment to be sampled in the field, as well as the most representative size-window for analysis. Also, MinSORTING provides an estimate of the volume/weight of the fractions not considered in both sizes finer and coarser than the selected size-window. A beta version of the software is available upon request from: alberto.resentini@unimib.it Mange, M., and Wright, D. (eds), 2007. Heavy minerals in use. Developments in Sedimentology Series, 58. Elsevier, Amsterdam. Garzanti, E., Andò, S., Vezzoli, G., 2008. Settling-equivalence of detrital minerals and grain-size dependence of sediment composition. Earth and Planetary Science Letters 273, 138-151. von Eynatten, H., and Dunkl, I., 2012. Assessing the sediment factory: The role of single grain analysis. Earth Sciences Reviews, 115, 97-120.

  7. Composition and distribution of selected munnopsid genera (Crustacea, Isopoda, Asellota) in Icelandic waters

    NASA Astrophysics Data System (ADS)

    Schnurr, Sarah; Brandt, Angelika; Brix, Saskia; Fiorentino, Dario; Malyutina, Marina; Svavarsson, Jörundur

    2014-02-01

    The Greenland-Scotland Ridge (GSR) is a major topographic feature, extending from Greenland to Scotland. It constrains the water exchange between the northernmost North Atlantic Ocean and the Greenland, Iceland and Norwegian Seas (GIN Seas) and thus forms a potential barrier for faunal exchange from the Arctic to the North Atlantic (and vice versa). Recently an increase in Atlantic water inflow has been observed, leading to changes in physical parameters (i.e. temperature and salinity), which may have an impact on the resident fauna. In this study, we analyzed the composition and distribution of six selected genera of the isopod family Munnopsidae (Crustacea) occurring north and south of the GSR. We examined 82 epibenthic sledge samples and 26 additional sub-samples taken in the course of the Benthic Invertebrates of Icelandic Waters (BIOICE) and Icelandic Marine Animals: Genetics and Ecology (IceAGE) projects, respectively, covering a total depth range from 103 to 2752 m depth. Overall, 58 of the evaluated stations originated in the area north of the GSR, while the remaining 50 samples were collected south of the ridge. In total, 10517 individuals could be assigned to 15 species, most belonging to the genus EurycopeSars, 1864. Due to the presence of the GSR as well as differences in the environment, we expected significant dissimilarities in faunal composition between the two study areas. However, most species (8) occurred on both sides of the ridge, while four species were restricted to the region north of Iceland, and three to the region south of the ridge. Depth (or factors related to depth) appeared to be the most important factor in driving distributional patterns of the studied species. Temperature was also an important driver, but not to the same extent as depth. On the contrary, salinity and sediment type did not have much influence on munnopsid distribution patterns. Hence, the presence of the ridge does not restrict faunal exchange between the northern North Atlantic Ocean and GIN Seas for most of the investigated species, which may be explained by the good swimming abilities and the ecological flexibility of these munnopsid species.

  8. Friction Stir Processing of Al-TiB2 In Situ Composite: Effect on Particle Distribution, Microstructure and Properties

    NASA Astrophysics Data System (ADS)

    Yadav, Devinder; Bauri, Ranjit

    2015-03-01

    Aluminum-based in situ composites suffer from the age-old issue of particle segregation along the grain boundaries after casting. In the present study, friction stir processing (FSP) was employed as a secondary process to improve the distribution of in situ formed TiB2 particles in Al-based composite. All the agglomerates of TiB2 were broken, and uniform distribution of particles was achieved after double-pass FSP. Also, FSP removed the casting defects and caused significant grain refinement of the Al matrix. The microstructure was characterized by equiaxed fine grains with average size of 3 µm and narrow grain size distribution. The microstructural refinements and homogenization after FSP not only enhanced the strength but also improved the ductility of the as-cast composite.

  9. Energy Analysis of Aluminosilicate Zeolites with Comprehensive Ranges of Framework Topologies, Chemical Compositions, and Aluminum Distributions.

    PubMed

    Muraoka, Koki; Chaikittisilp, Watcharop; Okubo, Tatsuya

    2016-05-18

    The contents and locations of Al in the zeolite frameworks are one of the key factors determining the physicochemical properties of zeolites. Systematic evaluation of the characteristics of zeolites with a wide variety of framework topologies, a wide range of Si/Al ratios, and various locations of Al is of great significance, but very challenging due to the limitation of the realizable ranges of Al contents in zeolites as well as the limited information on the Al locations obtained from the current analytical techniques. Here, we report the systematic analysis of the energetics of aluminosilicate zeolites with 209 existing framework topologies at different Si/Al ratios using molecular mechanics. More than 43 000 initial structures were generated to give comprehensive views of the energetics of zeolites. The results coincide well with the structural knowledge obtained experimentally. It was revealed that the relation between the relative framework energies versus the Al contents varies in accordance with the topologies, suggesting that the relative stability of zeolites depends not only on the topologies, but also on the substituting contents of Al. For particular topologies with the same Al contents, in addition, comparisons between random and specific distributions of Al showed that zeolite with Al at a particular T site is energetically more stable than those with random distributions, suggesting the inherent influences of the Al locations. The contents and locations of Al in zeolites likely have a certain preference that may reflect the range of chemical compositions, the Al distributions, and consequently the physicochemical properties of realizable aluminosilicate zeolites. PMID:27097121

  10. The primary divisions of life: a phylogenomic approach employing composition-heterogeneous methods

    PubMed Central

    Foster, Peter G.; Cox, Cymon J.; Embley, T. Martin

    2009-01-01

    The three-domains tree, which depicts eukaryotes and archaebacteria as monophyletic sister groups, is the dominant model for early eukaryotic evolution. By contrast, the ‘eocyte hypothesis’, where eukaryotes are proposed to have originated from within the archaebacteria as sister to the Crenarchaeota (also called the eocytes), has been largely neglected in the literature. We have investigated support for these two competing hypotheses from molecular sequence data using methods that attempt to accommodate the across-site compositional heterogeneity and across-tree compositional and rate matrix heterogeneity that are manifest features of these data. When ribosomal RNA genes were analysed using standard methods that do not adequately model these kinds of heterogeneity, the three-domains tree was supported. However, this support was eroded or lost when composition-heterogeneous models were used, with concomitant increase in support for the eocyte tree for eukaryotic origins. Analysis of combined amino acid sequences from 41 protein-coding genes supported the eocyte tree, whether or not composition-heterogeneous models were used. The possible effects of substitutional saturation of our data were examined using simulation; these results suggested that saturation is delayed by among-site rate variation in the sequences, and that phylogenetic signal for ancient relationships is plausibly present in these data. PMID:19571240

  11. Experimental Investigation of the Shuttle Transportation System Composite Overwrapped Pressure Vessels for Stress Rupture Life

    NASA Technical Reports Server (NTRS)

    Greene, Nathanael; Saulsberry, Regor; Yoder, Tommy; Forsyth, Brad; Carillo, Marlene; Thesken, John

    2006-01-01

    A viewgraph presentation describing stress rupture testing on Composite Overwrapped Pressure Vessels (COPV) is shown. The topics include: 1) Purpose for Testing; 2) NASA WSTF COPV Test Program; 3) NASA WSTF Test Facilities; 4) COPV Impact Study; 5) Fluids Compatibility Testing; 6) Stress Rupture Testing; and 7) COPV Lifting.

  12. Nano-enhanced aerospace composites for increased damage tolerance and service life damage monitoring

    NASA Astrophysics Data System (ADS)

    Paipetis, A.; Matikas, T. E.; Barkoula, N. M.; Karapappas, P.; Vavouliotis, A.; Kostopoulos, V.

    2009-03-01

    This study deals with new generation composite systems which apart from the primary reinforcement at the typical fiber scale (~10 ?m) are also reinforced at the nanoscale. This is performed via incorporation of nano-scale additives in typical aerospace matrix systems, such as epoxies. Carbon Nanotubes (CNTs) are ideal candidates as their extremely high aspect ratio and mechanical properties render them advantageous to other nanoscale materials. The result is the significant increase in the damage tolerance of the novel composite systems even at very low CNT loadings. By monitoring the resistance change of the CNT network, information both on the real time deformation state of the composite is obtained as a reversible change in the bulk resistance of the material, and the damage state of the material as an irreversible change in the bulk resistance of the material. The irreversible monotonic increase of the electrical resistance can be related to internal damage in the hybrid composite system and may be used as an index of the remaining lifetime of a structural component.

  13. Effects of dietary composition on life span of Drosophila buzzatii and its short-lived sibling species D. koepferae.

    PubMed

    Gomez, Federico H; Sambucetti, Pablo; Norry, Fabian M

    2013-08-01

    Two sibling Drosophila species dramatically divergent in longevity, Drosophila buzzatii and D. koepferae, were examined for possible effects of both developmental culture medium and dietary composition (DC) on longevity. Longevity was greatly increased in the longer lived D. buzzatii when flies were reared and fed on a rich-in-nutrient and cactus-based culture (R-CBC) as compared to longevity in a poor nutrient culture (PNC). In D. buzzatii, life span was further increased by exposing flies to short periods of a poor-in-nutrient and cactus-based culture (P-CBC). In contrast, variation in the here used nutrient composition did not change life span in the shorter lived D. koepferae, as longevity in this species did not differ among R-CBC, P-CBC and PNC cultures. Hormesis is a plausible explanation for the beneficial biological effects against aging arising from brief exposure to a lowed calorie food source in D. buzzatii. This study shows that genetic variation between closely related species is substantial for dietary effects on longevity. PMID:23835870

  14. Life on the boundary: Environmental factors as drivers of habitat distribution in the littoral zone

    NASA Astrophysics Data System (ADS)

    Cefalì, Maria Elena; Cebrian, Emma; Chappuis, Eglantine; Pinedo, Susana; Terradas, Marc; Mariani, Simone; Ballesteros, Enric

    2016-04-01

    The boundary between land and sea, i.e. the littoral zone, is home to a large number of habitats whose distribution is primarily driven by the distance to the sea level but also by other environmental factors such as littoral's geomorphological features, wave exposure, water temperature or orientation. Here we explore the relative importance of those major environmental factors that drive the presence of littoral rocky habitats along 1100 Km of Catalonia's shoreline (Spain, NW Mediterranean) by using Geographic Information Systems and Generalized Linear Models. The distribution of mediolittoral and upper infralittoral habitats responded to different environmental factors. Mediolittoral habitats showed regional differences drawn by sea-water temperature and substrate type. Wave exposure (hydrodynamism), slope and geological features were only relevant to those mediolittoral habitats with specific environmental needs. We did not find any regional pattern of distribution in upper infralittoral habitats, and selected factors only played a moderate role in habitat distribution at the local scale. This study shows for the first time that environmental factors determining habitat distribution differ within the mediolittoral and the upper infralittoral zones and provides the basis for further development of models oriented at predicting the distribution of littoral marine habitats.

  15. Fatigue, fracture, and life prediction criteria for composite materials in magnets

    SciTech Connect

    Wong, F.M.G.

    1990-06-01

    An explosively-bonded copper/Inconel 718/copper laminate conductor was proposed to withstand the severe face compression stresses in the central core of the Alcator C-MOD tokamak toroidal field (TF) magnet. Due to the severe duty of the TF magnet, it is critical that an accurate estimate of useful life be determined. As part of the effort to formulate an appropriate life prediction, fatigue crack growth experiments were performed on the laminate as well as its components. Metallographic evaluation of the laminate interface revealed many shear bands in the Inconel 718. Shear bands and shear band cracks were produced in the Inconel 718 as a result of the explosion bonding process. These shear bands were shown to have a detrimental effect on the crack growth behavior of the laminate, by significantly reducing the load carrying capability of the reinforcement layer and providing for easy crack propagation paths. Fatigue crack growth rate was found not only to be dependent on temperature but also on orientation. Fatigue cracks grew faster in directions which contained shear bands in the plane of the propagating crack. Fractography showed crack advancement by fatigue cracking in the Inconel 718 and ductile tearing of the copper at the interface. However, further away from the interfaces, the copper exhibited fatigue striations indicating that cracks were now propagating by fatigue. Laminate life prediction results showed a strong dependence on shear band orientation, and exhibited little variation between room temperature and 77{degree}K. Predicted life of this laminate was lower when the crack propagation was along a shear band than when crack propagation was across the shear bands. Shear bands appear to have a dominating effect on crack growth behavior.

  16. A requirement for reduced pressure and modified atmosphere composition in lunar and martian biological life support systems

    NASA Astrophysics Data System (ADS)

    Dixon, Mike; Stasiak, Michael; Wehkamp, Cara Ann; Lawson, Jamie

    The Controlled Environment Systems Research Facility at the PlaceTypeUniversity of Place- NameGuelph (country-regionplaceCanada) represents an extensive collection of variable pressure plant growth chambers devoted to the study of biological systems including plants and microbes, in life support roles for space exploration. To simplify engineering requirements for plant growth structures on the Moon or Mars, lower pressures are required in order to reduce mass and decrease atmospheric leakage. Few facilities exist that can provide low pressure plant growth capabilities coupled with complete control over temperature, vapour pressure deficit (humidity), gas composition, nutrient delivery, and pressure. The Controlled Environment Systems Research Facility maintains five canopy-scale hypobaric plant growth chambers with capabilities ideally suited for low pressure advanced life support research. System performance evaluations during low pressure experiments on radish (Raphanus sativa L. cv. Cherry Bomb II) have demonstrated temperature control of +/- 0.5 ° C, vapour pressure deficit control of +/- 0.5 mb, CO2 injection control of +/- 20 ` ımol mol-1 , and leakage rates of less than 1% per day. Keywords: hypobaric, plant growth chamber, advanced life support, controlled environment, low pressure, atmospheric control

  17. Unequally Distributed Psychological Assets: Are There Social Disparities in Optimism, Life Satisfaction, and Positive Affect?

    PubMed Central

    Boehm, Julia K.; Chen, Ying; Williams, David R.; Ryff, Carol; Kubzansky, Laura D.

    2015-01-01

    Socioeconomic status is associated with health disparities, but underlying psychosocial mechanisms have not been fully identified. Dispositional optimism may be a psychosocial process linking socioeconomic status with health. We hypothesized that lower optimism would be associated with greater social disadvantage and poorer social mobility. We also investigated whether life satisfaction and positive affect showed similar patterns. Participants from the Midlife in the United States study self-reported their optimism, satisfaction, positive affect, and socioeconomic status (gender, race/ethnicity, education, occupational class and prestige, income). Social disparities in optimism were evident. Optimistic individuals tended to be white and highly educated, had an educated parent, belonged to higher occupational classes with more prestige, and had higher incomes. Findings were generally similar for satisfaction, but not positive affect. Greater optimism and satisfaction were also associated with educational achievement across generations. Optimism and life satisfaction are consistently linked with socioeconomic advantage and may be one conduit by which social disparities influence health. PMID:25671665

  18. Out-Life Characteristics of IM7/977-3 Composites

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G.; Sutter, James K.; Hou, Tan-Hung; Scheiman, Daniel A.; Martin, Richard E.; Maryanski, Michael; Schlea, Michelle; Gardner, John M.; Schiferl, Zack R.

    2010-01-01

    The capability to manufacture large structures leads to weight savings and reduced risk relative to joining smaller components. However, manufacture of increasingly large composite components is pushing the out-time limits of epoxy/ carbon fiber prepreg. IM7/977-3 is an autoclave processable prepreg material, commonly used in aerospace structures. The out-time limit is reported as 30 days by the manufacturer. The purpose of this work was to evaluate the material processability and composite properties of 977-3 resin and IM7/977-3 prepreg that had been aged at room temperature for up to 60 days. The effects of room temperature aging on the thermal and visco-elastic properties of the materials were investigated. Neat resin was evaluated by differential scanning calorimetry to characterize thermal properties and change in activation energy of cure. Neat resin was also evaluated by rheometry to characterize its processability in composite fabrication. IM7/977-3 prepreg was evaluated by dynamic mechanical analysis to characterize the curing behavior. Prepreg tack was also evaluated over 60 days. The overall test results suggested that IM7/977-3 was a robust material that offered quality laminates throughout this aging process when processed by autoclave.

  19. The plankton community in Norwegian coastal waters—abundance, composition, spatial distribution and diel variation

    NASA Astrophysics Data System (ADS)

    Bratbak, Gunnar; Jacquet, Stéphan; Larsen, Aud; Pettersson, Lasse H.; Sazhin, Andrey F.; Thyrhaug, Runar

    2011-09-01

    The purpose of the present study was to explore the composition and variation of the pico-, nano- and micro-plankton communities in Norwegian coastal waters and Skagerrak, and the co-occurrence of bacteria and viruses. Samples were collected along three cruise transects from Jæren, Lista and Oksøy on the south coast of Norway and into the North Sea and Skagerrak. We also followed a drifting buoy for 55 h in Skagerrak in order to observe diel variations. Satellite ocean color images (SeaWiFS) of the chlorophyll a (chl a) distribution compared favorably to in situ measurements in open waters, while closer to the shore remote sensing chl a data was overestimated compared to the in situ data. Using light microscopy, we identified 49 micro- and 15 nanoplankton sized phototrophic forms as well as 40 micro- and 12 nanoplankton sized heterotrophic forms. The only picoeukaryote (0.2-2.0 μm) we identified was Resultor micron (Pedinophyceae ). Along the transects a significant variation in the distribution and abundance of different plankton forms were observed, with Synechococcus spp and autotrophic picoeukaryotes as the most notable examples. There was no correlation between viruses and chl a, but between viruses and bacteria, and between viruses and some of the phytoplankton groups, especially the picoeukaryotes. Moreover, there was a negative correlation between nutrients and small viruses (Low Fluorescent Viruses) but a positive correlation between nutrients and large viruses (High Fluorescent Viruses). The abundance of autotrophic picoplankton, bacteria and viruses showed a diel variation in surface waters with higher values around noon and late at night and lower values in the evening. Synechococcus spp were found at 20 m depth 25-45 nautical miles from shore apparently forming a bloom that stretched out for more than 100 nautical miles from Skagerrak and up the south west coast of Norway. The different methods used for assessing abundance, distribution and diversity of microorganisms yielded complementary information about the plankton community. Flow cytometry enabled us to map the distribution of the smaller phytoplankton forms, bacteria and viruses in more detail than has been possible before but detection and quantification of specific forms (genus or species) still requires taxonomic skills, molecular analysis or both.

  20. Sediment size distribution and composition in a reservoir affected by severe water level fluctuations.

    PubMed

    López, Pilar; López-Tarazón, José A; Casas-Ruiz, Joan P; Pompeo, Marcelo; Ordoñez, Jaime; Muñoz, Isabel

    2016-01-01

    The reservoir sediments are important sinks for organic carbon (OC), the OC burial being dependent on two opposite processes, deposition and mineralization. Hence factors such as severe water level fluctuations are expected to influence the rate of OC accumulation as they may affect both deposition and mineralization. The Barasona Reservoir has been historically threatened by siltation, whilst the use of water for irrigation involves a drastic decrease of the water level. In this context, we have studied the physical and chemical characteristics (grain size, major and minor elemental compositions, organic and inorganic carbon, and nitrogen) of the recent sediments of the Barasona Reservoir and the relationships among them in order to: a) elucidate the main processes governing OC accumulation, b) evaluate the rate of OC mineralization and c) approach the effect of drought on the sediment characteristics in this system. Our results indicated that Barasona sediments were dominated by fine silts (>60%) and clays (>20%), the mean particle size decreasing from tail to dam. Desiccation increased particle sorting and size distribution became bimodal, but no effect on average size was observed. Attending to the composition, Barasona sediments were very homogeneous with low concentrations of nitrogen (TN) and phosphorus (<1.2 g kg(-1) dw and <0.6 g kg(-1) dw, respectively) and high concentration of OC (≈36 g kg(-1) dw). TN was negatively related to dry weight. Sediment mixing due to drastic changes in water level may have favoured the observed homogeneity of Barasona sediments affecting carbon, major ions and grain size. The high amount of OC deposited in Barasona sediment suggested that the adsorption of OC onto fine particles was more important than in boreal lakes. The rate of oxygen consumption by wet sediment ranged from 2.26 to 3.15 mg O2 m(-2) day(-1), values close to those compiled for Mediterranean running waters. PMID:26105704

  1. Spatial distribution and cellular composition of adult brain proliferative zones in the teleost, Gymnotus omarorum

    PubMed Central

    Olivera-Pasilio, Valentina; Peterson, Daniel A.; Castelló, María E.

    2014-01-01

    Proliferation of stem/progenitor cells during development provides for the generation of mature cell types in the CNS. While adult brain proliferation is highly restricted in the mammals, it is widespread in teleosts. The extent of adult neural proliferation in the weakly electric fish, Gymnotus omarorum has not yet been described. To address this, we used double thymidine analog pulse-chase labeling of proliferating cells to identify brain proliferation zones, characterize their cellular composition, and analyze the fate of newborn cells in adult G. omarorum. Short thymidine analog chase periods revealed the ubiquitous distribution of adult brain proliferation, similar to other teleosts, particularly Apteronotus leptorhynchus. Proliferating cells were abundant at the ventricular-subventricular lining of the ventricular-cisternal system, adjacent to the telencephalic subpallium, the diencephalic preoptic region and hypothalamus, and the mesencephalic tectum opticum and torus semicircularis. Extraventricular proliferation zones, located distant from the ventricular-cisternal system surface, were found in all divisions of the rombencephalic cerebellum. We also report a new adult proliferation zone at the caudal-lateral border of the electrosensory lateral line lobe. All proliferation zones showed a heterogeneous cellular composition. The use of short (24 h) and long (30 day) chase periods revealed abundant fast cycling cells (potentially intermediate amplifiers), sparse slow cycling (potentially stem) cells, cells that appear to have entered a quiescent state, and cells that might correspond to migrating newborn neural cells. Their abundance and migration distance differed among proliferation zones: greater numbers and longer range and/or pace of migrating cells were associated with subpallial and cerebellar proliferation zones. PMID:25249943

  2. [Composition, abundance and distribution of populations of commercially important gastropods in La Guajira, Colombian Caribbean].

    PubMed

    Nieto-Bernal, Ramón; Luis, Chasqui; Rodriguez, Angélica María; Castro, Erick; Gil-Agudelo, Diego L

    2013-06-01

    In the continental Colombian Caribbean the conch resource exploitation and the status of snails populations has been poorly studied, which are reflected in the lack of fisheries management. This study assesses composition, population density and distribution of the gastropods species that make conch resource in La Guajira region. Underwater visual censuses for snails were performed between September-November 2009 in 145100x4m (400m2) transects, spanning a total area of 56920m2 between Riohacha and Cabo de la Vela. The study was complemented with the evaluation of composition, abundance and size of gastropods conch found in the discarded-by-fishermen shell mounds in 13 beaches. In October 2010 another 40 transects were evaluated (16 000 m2) from the Southern of Riohacha to the Camarones village (La Guajira). We found a total of 9911 snails belonging to 12 species, the most abundant being Strombus pugilis with 8 912 individuals and an average density of 1 538.4 +/- 3 662.6 ind./ha, followed by Vasum muricatum with 374 individuals and an average density of 51.8 +/- 91.2 ind./ha. Calculating the importance value index (IVI) for both living organisms as the empty shells on beaches, shows that Turbinella angulata is the most used species by artisanal fishermen in the region. Cassis madagascariensis and Cassis tuberosa are also important snail resources in the region (as suggested by the number of empty shells found in beaches), but its densities were low. Strombus gigas, with only three living organisms found in the area, presented the lowest abundance ever found in the Colombian Caribbean (0.52 +/- 3.6 ind./ha), showing that queen conch population in La Guajira cannot support commercial exploitation. The abundance of discarded S. gigas shells on beaches suggests resource exploitation in the recent past. Results remarks the urgency of implementing management plans for snail fisheries in the region. PMID:23885583

  3. Assessing Historical Fish Community Composition Using Surveys, Historical Collection Data, and Species Distribution Models

    PubMed Central

    Labay, Ben; Cohen, Adam E.; Sissel, Blake; Hendrickson, Dean A.; Martin, F. Douglas; Sarkar, Sahotra

    2011-01-01

    Accurate establishment of baseline conditions is critical to successful management and habitat restoration. We demonstrate the ability to robustly estimate historical fish community composition and assess the current status of the urbanized Barton Creek watershed in central Texas, U.S.A. Fish species were surveyed in 2008 and the resulting data compared to three sources of fish occurrence information: (i) historical records from a museum specimen database and literature searches; (ii) a nearly identical survey conducted 15 years earlier; and (iii) a modeled historical community constructed with species distribution models (SDMs). This holistic approach, and especially the application of SDMs, allowed us to discover that the fish community in Barton Creek was more diverse than the historical data and survey methods alone indicated. Sixteen native species with high modeled probability of occurrence within the watershed were not found in the 2008 survey, seven of these were not found in either survey or in any of the historical collection records. Our approach allowed us to more rigorously establish the true baseline for the pre-development fish fauna and then to more accurately assess trends and develop hypotheses regarding factors driving current fish community composition to better inform management decisions and future restoration efforts. Smaller, urbanized freshwater systems, like Barton Creek, typically have a relatively poor historical biodiversity inventory coupled with long histories of alteration, and thus there is a propensity for land managers and researchers to apply inaccurate baseline standards. Our methods provide a way around that limitation by using SDMs derived from larger and richer biodiversity databases of a broader geographic scope. Broadly applied, we propose that this technique has potential to overcome limitations of popular bioassessment metrics (e.g., IBI) to become a versatile and robust management tool for determining status of freshwater biotic communities. PMID:21966438

  4. A Novel Conditional Probability Density Distribution Surface for the Analysis of the Drop Life of Solder Joints Under Board Level Drop Impact

    NASA Astrophysics Data System (ADS)

    Gu, Jian; Lei, YongPing; Lin, Jian; Fu, HanGuang; Wu, Zhongwei

    2016-01-01

    The scattering of fatigue life data is a common problem and usually described using the normal distribution or Weibull distribution. For solder joints under drop impact, due to the complicated stress distribution, the relationship between the stress and the drop life is so far unknown. Furthermore, it is important to establish a function describing the change in standard deviation for solder joints under different drop impact levels. Therefore, in this study, a novel conditional probability density distribution surface (CPDDS) was established for the analysis of the drop life of solder joints. The relationship between the drop impact acceleration and the drop life is proposed, which comprehensively considers the stress distribution. A novel exponential model was adopted for describing the change of the standard deviation with the impact acceleration (0 → +∞). To validate the model, the drop life of Sn-3.0Ag-0.5Cu solder joints was analyzed. The probability density curve of the logarithm of the fatigue life distribution can be easily obtained for a certain acceleration level fixed on the acceleration level axis of the CPDDS. The P- A- N curve was also obtained using the functions μ( A) and σ( A), which can reflect the regularity of the life data for an overall reliability P.

  5. Resonance line shape, strain and electric potential distributions of composite magnetoelectric sensors

    NASA Astrophysics Data System (ADS)

    Gerken, Martina

    2013-06-01

    Multiferroic composite magnetoelectric (ME) sensors are based on the elastic coupling of a magnetostrictive phase and a piezoelectric phase. A deformation of the magnetostrictive phase causes strain in the piezoelectric phase and thus an induced voltage. Such sensors may be applied both for static as well as for dynamic magnetic field measurements. Particularly high sensitivities are achieved for operation at a mechanical resonance. Here, the resonance line shape of layered (2-2 composite) cantilever ME sensors at the first bending-mode resonance is investigated theoretically. Finite element method (FEM) simulations using a linear material model reveal an asymmetric resonance profile and a zero-response frequency for the ME coefficient. Frequency-dependent strain and electric potential distributions inside the magnetoelectric composite are studied for the case of a magnetostrictive-piezoelectric bilayer. It is demonstrated that a positive or a negative voltage may be induced across the piezoelectric layer depending on the position of the neutral plane. The frequency-dependent induced electric potential is investigated for structured cantilevers that exhibit magnetostriction only at specific positions. For static operation an induced voltage is obtained locally at positions with magnetostriction. In addition to this direct effect a resonance-assisted effect is observed for dynamic operation. Magnetostriction in a limited area of the cantilever causes a global vibration of the cantilever. Thus, deformation of the piezoelectric layer and an induced electric potential also occur in areas of the cantilever without magnetostriction. The direct and the resonance-assisted pathway may induce voltages of equal or of opposite sign. The net induced voltage results from the superposition of the two effects. As the resonance-assisted induced voltage changes sign upon passing the resonance frequency, while the direct component is constant, an asymmetric line shape and a zero-response frequency result for the ME coefficient. The zero-response oscillator frequency may be below or above the resonance frequency. The calculated FEM resonance line shapes are fitted successfully to a superposition function of a constant component and a resonant component with a Lorentzian line shape. Equivalence of the superposition function line shape to a Fano resonance profile is derived for frequencies around the resonance. Fano resonances are ubiquitous in physics occurring due to the constructive and destructive quantum interference of two different scattering pathways, e.g., for photons or electrons. The superposition fit parameters describing the resonance line shape are calculated as a function of the cantilever substrate thickness. The inclusion of loss by adjustment of the damping parameter is discussed. The results derived here also are applicable to higher order modes or longitudinal resonance modes.

  6. Progressive failure methodologies for predicting residual strength and life of laminated composites

    NASA Technical Reports Server (NTRS)

    Harris, Charles E.; Allen, David H.; Obrien, T. Kevin

    1991-01-01

    Two progressive failure methodologies currently under development by the Mechanics of Materials Branch at NASA Langley Research Center are discussed. The damage tolerance/fail safety methodology developed by O'Brien is an engineering approach to ensuring adequate durability and damage tolerance by treating only delamination onset and the subsequent delamination accumulation through the laminate thickness. The continuum damage model developed by Allen and Harris employs continuum damage laws to predict laminate strength and life. The philosophy, mechanics framework, and current implementation status of each methodology are presented.

  7. Distribution and species composition of juvenile and adult scombropids (Teleostei, Scombropidae) in Japanese coastal waters.

    PubMed

    Itoi, S; Odaka, J; Yuasa, K; Akeno, S; Nakajima, A; Suenaga, A; Noda, T; Akimoto, S; Myojin, T; Ikeda, Y; Masuda, Y; Takai, N; Yoshihara, K; Sugita, H

    2010-02-01

    Two scombropid fishes, Scombrops boops and Scombrops gilberti, are closely related and commercially important species in Japan. These species are often confused in commercial markets because of their morphological similarity. In this study, scombropid specimens collected from various Japanese coastal waters were subjected to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and phylogenetic analysis of the 16S rRNA gene in mitochondrial DNA. These analyses showed that all the scombropid specimens collected from localities in the Sea of Japan were identified as S. boops, whereas those from the Pacific Ocean included two species, S. boops and S. gilberti. Almost all juvenile (<200 mm standard body length, S(L)) S. gilberti originated from the Pacific coastal waters of the northern Japan, whereas adults (>400 mm S(L)) were found only in deep water off the Izu Peninsula to the Izu Islands. This suggests that S. gilberti might migrate extensively during its life cycle. In addition, differences in the number of specimens and the distribution between the two species suggest that S. gilberti is less abundant than S. boops in Japanese waters. PMID:20738713

  8. The microscopic state of the solar wind: Links between composition, velocity distributions, waves and turbulence

    NASA Technical Reports Server (NTRS)

    Marsch, E.

    1995-01-01

    An overview is given of the microscopic state of the solar wind with emphasis on recent Ulysses high-latitude observations and previous Helios in-ecliptic observations. The possible links between composition, ionization state. velocity distribution functions of electrons, protons and heavy ions. kinetic plasma waves and MHD-scale turbulence are elaborated. Emphasis is placed on a connection of interplanetary kinetic-scale phenomena with their generating microscopic processes in the corona. The fast streams seem to consist of mesoscale pressure-balanced plasma filaments and magnetic flux tubes, reminiscent of the supergranular-size structures building the open corona, from which copious Alfven waves emanate. The wind from the magnetically structured and active corona shows developed compressive turbulence and considerable abundance and ionization state variations. Some modelling attempts to explain the observed element fractionation are briefly reviewed. The causes of the nonthermal particle features. such as proton-ion differential streaming, ion beams. temperature anisotropies, and skewed distributions associated with collisionless heat conduction, are ultimately to be searched in the fact, that the corona is never quiescent but fundamentally variable in space and time. Consequently, the radial evolution of the internal state of the wind resembles at all latitudes a complicated relaxation process, in the course of which the free (in comparison with LTE conditions) particle kinetic energy is converted into plasma waves and MHD turbulence on a wide range of scales. This leads to intermittent wave-particle interactions and unsteady anomalous transport, mixed with the weak effects of the rare Coulomb collisions. Spherical expansion and large-scale inhomogeneity forces the wind to attain microscopically a complex internal state of dynamic statistical equilibrium.

  9. Muscle-spindle distribution in relation to the fibre-type composition of masseter in mammals.

    PubMed Central

    Rowlerson, A; Mascarello, F; Barker, D; Saed, H

    1988-01-01

    The various parts of the masseter muscle complex (pars superficialis, pars profunda, zygomaticomandibularis, maxillomandibularis) in the rat, guinea-pig, rabbit, cat and macaque monkey were examined to discover whether they showed any relationship between the distribution of muscle spindles and extrafusal fibre types. Intrafusal (spindle) and extrafusal fibre types in masseter were compared with those in limb muscles and were identified by a combination of standard histochemical methods and indirect immunoperoxidase staining with antibodies specific for the various isoforms of myosin characteristic of fibre types in mammalian muscle. In general, the fibre-type properties of intrafusal fibres in masseter resembled those in limb muscle spindles, but the extrafusal fibre-type composition was unlike that in most limb muscles. In the rat masseter, most of the spindles were clustered together in a few very restricted areas. Extensive fusion of the external capsules of adjacent spindles, resulting in the formation of giant spindles, was seen in the cat and monkey masseter; this was sometimes accompanied by the enclosure of extrafusal fibres within the fused spindles. Common to all species, but strongest of all in the rat, was a close association between the distributions of muscle spindles and extrafusal Type I (slow twitch) fibres within the masseter complex. Muscle spindles and Type I fibres were either absent or rarest in the superficial part of masseter, but were most common in the deep layer (pars profunda) or zygomaticomandibularis. The functional significance of these observations is discussed. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 PMID:2978294

  10. Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai.

    PubMed

    Wang, Xuemei; Chen, Jianmin; Cheng, Tiantao; Zhang, Renyi; Wang, Xinming

    2014-09-01

    The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe (visibility<2km) and moderate (2km≤visibility<3km) haze, mainly distributed in winter and spring. The mean particle number concentration was about 17,000/cm(3) in haze, more than 2 times that in clean days. The greatest increase of particle number concentration was in 0.5-1μm and 1-10μm size fractions during haze events, about 17.78 times and 8.78 times those of clean days. The largest increase of particle number concentration was within 50-100nm and 100-200nm fractions during photochemical smog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15μm(3)/cm(3) and 949, 649, 206μm(2)/cm(3), respectively. As haze events got more severe, the number concentration of particles smaller than 50nm decreased, but the particles of 50-200nm and 0.5-1μm increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4(+), SO4(2-) and NO3(-) increased greatly, followed by Na(+), K(+), Ca(2+) and Cl(-). These ions were very different in size-resolved particles during haze and photochemical smog episodes. PMID:25193840

  11. Rate of Return to Education: A Distributional Analysis Using the LifePaths Model

    ERIC Educational Resources Information Center

    Boothby, Daniel; Rowe, Geoff

    2002-01-01

    This paper reports estimates of the distribution of individual private rates of return to undergraduate and community college education by field of study for Canada. It is important to know the dispersion of the private rate of return to post-secondary education, as well as its average level. There are very different implications for…

  12. "A Bit More Life in the Leadership": Co-Principalship as Distributed Leadership Practice

    ERIC Educational Resources Information Center

    Gronn, Peter; Hamilton, Andrew

    2004-01-01

    Most commentators think of leadership as individually focused, a preference which reflects historical understandings and usage. With the example of a co-principalship, this article shows how focused leadership is at odds with the reality of distributed work practice. The article reports research at College A, a Catholic all-girls' secondary school…

  13. Method of improving fatigue life of cast nickel based superalloys and composition

    DOEpatents

    Denzine, Allen F.; Kolakowski, Thomas A.; Wallace, John F.

    1978-03-14

    The invention consists of a method of producing a fine equiaxed grain structure (ASTM 2-4) in cast nickel-base superalloys which increases low cycle fatigue lives without detrimental effects on stress rupture properties to temperatures as high as 1800.degree. F. These superalloys are variations of the basic nickel-chromium matrix, hardened by gamma prime [Ni.sub.3 (Al, Ti)] but with optional additions of cobalt, tungsten, molybdenum, vanadium, columbium, tantalum, boron, zirconium, carbon and hafnium. The invention grain refines these alloys to ASTM 2 to 4 increasing low cycle fatigue life by a factor of 2 to 5 (i.e. life of 700 hours would be increased to 1400 to 3500 hours for a given stress) as a result of the addition of 0.01% to 0.2% of a member of the group consisting of boron, zirconium and mixtures thereof to aid heterogeneous nucleation. The alloy is vacuum melted and heated to 250.degree.-400.degree. F. above the melting temperature, cooled to partial solidification, thus resulting in said heterogeneous nucleation and fine grains, then reheated and cast at about 50.degree.-100.degree. F. of superheat. Additions of 0.1% boron and 0.1% zirconium (optional) are the preferred nucleating agents.

  14. Entire Life Time Monitoring of Filament Wound Composite Cylinders Using Bragg Grating Sensors: II. Process Monitoring

    NASA Astrophysics Data System (ADS)

    Hernández-Moreno, H.; Collombet, F.; Douchin, B.; Choqueuse, D.; Davies, P.; González Velázquez, J. L.

    2009-08-01

    This article is the second of a series of three papers concerning monitoring of filament wound cylinders using Bragg gratings. In this second part, the tooling presented in Part I is used to embed gratings and thermocouples in filament wound glass reinforced epoxy composite cylinders during fabrication. Bragg grating strain was obtained from wavelength and temperature response, by a calibration technique described here. Results from tests on five cylinders show the Bragg grating’s capability to monitor strain evolution during fabrication, and the capacity to detect several phenomena occurring during cure is established, in addition to quantifying the initial material condition of the cylinder before it enters service.

  15. Biochemical composition of deep-sea decapod crustaceans with two different benthic life strategies off the Portuguese south coast

    NASA Astrophysics Data System (ADS)

    Rosa, R.; Nunes, M. L.

    2003-01-01

    The objectives of the present study were to characterize the benthic life strategies of Aristeus antennatus (Crustacea: Penaeidea), Parapenaeus longirostris (Crustacea: Penaeidea) and Nephrops norvegicus (Crustacea: Astacidea) on the basis of biochemical composition (proximate chemical composition, total lipids, glycogen and cholesterol contents), and its response to biological and environmental factors (sex, maturation, reproduction, food availability and depth) into account. The specimens were collected at depths between 200 and 600 m off the Portuguese south coast (Algarve). The nektobenthic species ( A. antennatus and P. longirostris) showed higher protein, lipid, cholesterol and glycogen contents, and lower moisture content in the muscle than the benthic-endobenthic species ( N. norvegicus). Consequently, the energy content of the nektobenthic species was also higher. Principal component analyses were used to assess the relationship between the different biochemical contents and to relate them to the biotic and abiotic factors. Depth seems to have the most important role in the observed trends of the biochemical composition. The increase of the ovarian lipid levels occurs as a result of the maturation process. The highest values were obtained in mature N. norvegicus females. The differences can be due to maternal investment (lipid metabolism of the female is geared to the provision of egg lipid), since N. norvegicus produce large lecithotrophic eggs. The biochemical differences observed in the three species did not seem to be due to distinct trophic strategies, but instead were a consequence of depth, which may have a significant interspecific effect on food intake. It was also evident that reproductive cycle has profound effects upon the biochemistry of the three species. Gonadal maturation has large associated energy costs due to the increase in biosynthetic work. Moreover, the biochemical composition would be influenced by or synchronized with seasonal feeding activity or food availability.

  16. USE OF MULTI-PHOTON LASER-SCANNING MICROSCOPY TO DESCRIBE THE DISTRIBUTION OF XENOBIOTIC CHEMICALS IN FISH EARLY LIFE STAGES

    EPA Science Inventory

    To better understand the mechanisms by which persistent bioaccumulative toxicants (PBTs) produce toxicity during fish early life stages (ELS), dose response relationships need to be determined in relation to the dynamic distribution of chemicals in sensitive tissues. In this stud...

  17. Species Composition and Distribution of Adult Anopheles (Diptera: Culicidae) in Panama

    PubMed Central

    LOAIZA, J. R.; BERMINGHAM, E.; SCOTT, M. E.; ROVIRA, J. R.; CONN, J. E.

    2010-01-01

    Anopheles (Diptera: Culicidae) species composition and distribution were studied using human landing catch data over a 35-yr period in Panama. Mosquitoes were collected from 77 sites during 228 field trips carried out by members of the National Malaria Eradication Service. Fourteen Anopheles species were identified. The highest average human biting rates were recorded from Anopheles (Nyssorhynchus) albimanus (Wiedemann) (9.8 bites/person/night) and Anopheles (Anopheles) punctimacula (Dyar and Knab) (6.2 bites/person/night). These two species were also the most common, present in 99.1 and 74.9%, respectively, of the sites. Anopheles (Nyssorhynchus) aquasalis (Curry) was encountered mostly in the indigenous Kuna Yala Comarca along the eastern Atlantic coast, where malaria case history and average human biting rate (9.3 bites/person/night) suggest a local role in malaria transmission. An. albimanus, An. punctimacula, and Anopheles (Anopheles) vestitipennis (Dyar and Knab) were more abundant during the rainy season (May–December), whereas An. aquasalis was more abundant in the dry season (January–April). Other vector species collected in this study were Anopheles (Kerteszia) neivai (Howard, Dyar, and Knab) and Anopheles (Anopheles) pseudopunctipennis s.l. (Theobald). High diversity of Anopheles species and six confirmed malaria vectors in endemic areas of Panama emphasize the need for more detailed studies to better understand malaria transmission dynamics. PMID:18826025

  18. Composition and Distribution of Streambed Sediments in the Penobscot River, Maine, May 1999

    USGS Publications Warehouse

    Dudley, Robert W.; Giffen, Sarah E.

    2001-01-01

    Sediment samples were collected and geophysical surveys were run along 50 miles of the Penobscot River, Maine, in the spring of 1999 to produce maps that describe the composition and distribution of streambed sediments for selected areas in the river channel. The objective of the sediment survey was to locate areas along the river where fine-grained, easily transportable sediment types were deposited between Old Town and Medway, Maine. These data can be used to design future sediment-sampling programs to assess the quality of streambed sediments and evaluate the health of the Penobscot River. This report describes the results of the sediment survey and the methods used to collect, analyze, and interpret the data used to create maps of streambed-sediment types in the study area. Deposits of fine-grained sediments (mud and sand) are scattered along the shorelines of the mainland and the islands and at the downstream ends of islands and at the mouths of brooks and streams. The most extensive depositional areas were found in the Mattaseunk Dam impoundment near Medway. The main areas of the river channel consist primarily of gravel, sand, and rock.

  19. Distribution and size composition of the arctic lamprey Lethenteron camtschaticum in the North Pacific

    NASA Astrophysics Data System (ADS)

    Orlov, A. M.; Baitalyuk, A. A.; Pelenev, D. V.

    2014-03-01

    Results of the long-term study of the spatial and vertical distribution of the parasitic anadromous Arctic lamprey Lethenteron camtschaticum (Tilesius, 1811) (Petromyzontidae) in the North Pacific and data on its size composition are given. This species is most frequent in the northwestern Sea of Japan and the western Bering Sea. The maximum concentrations are noted in waters of southern Primorye, southwestern Sakhalin, the northwestern part of the Sea of Okhotsk, and the northern part of the Bering Sea, which is probably explained by the increased number of its victims, Pacific salmon. Near the bottom, Pacific lampreys are extremely few and are primarily encountered at depths less that 400 m, and in the Pelagic zone, in the 100-m layer. The catches have contained Arctic lampreys having a total length of 15-79 cm. The lampreys of several size groups in the catches may indicate that L. camtschaticum spends not less than four years in the sea. No relationship has been found between the body length and the capture depth. Analyzed are the relationships between the body length and weight and the body length and the condition factor. The seasonal dynamics of these indices are considered.

  20. Species composition and distribution of adult Anopheles (Diptera: Culicidae) in Panama.

    PubMed

    Loaiza, J R; Bermingham, E; Scott, M E; Rovira, J R; Conn, J E

    2008-09-01

    Anopheles (Diptera: Culicidae) species composition and distribution were studied using human landing catch data over a 35-yr period in Panama. Mosquitoes were collected from 77 sites during 228 field trips carried out by members of the National Malaria Eradication Service. Fourteen Anopheles species were identified. The highest average human biting rates were recorded from Anopheles (Nyssorhynchus) albimanus (Wiedemann) (9.8 bites/person/night) and Anopheles (Anopheles) punctimacula (Dyar and Knab) (6.2 bites/person/night). These two species were also the most common, present in 99.1 and 74.9%, respectively, of the sites. Anopheles (Nyssorhynchus) aquasalis (Curry) was encountered mostly in the indigenous Kuna Yala Comarca along the eastern Atlantic coast, where malaria case history and average human biting rate (9.3 bites/person/night) suggest a local role in malaria transmission. An. albimanus, An. punctimacula, and Anopheles (Anopheles) vestitipennis (Dyar and Knab) were more abundant during the rainy season (May-December), whereas An. aquasalis was more abundant in the dry season (January-April). Other vector species collected in this study were Anopheles (Kerteszia) neivai (Howard, Dyar, and Knab) and Anopheles (Anopheles) pseudopunctipennis s.l. (Theobald). High diversity of Anopheles species and six confirmed malaria vectors in endemic areas of Panama emphasize the need for more detailed studies to better understand malaria transmission dynamics. PMID:18826025

  1. Alumina Size Distributions from High-Pressure Composite Solid-Propellant Combustion

    NASA Technical Reports Server (NTRS)

    Povinelli, Louis A.; Rosenstein, Robert A.

    1964-01-01

    Alumina size distributions were obtained for both a coarse and a fine oxidizer composite propellant burning in a nitrogen atmosphere over the pressure range from atmospheric to 500 pounds per square inch. The amount of additive agglomeration was found to be significantly higher for the coarse oxidizer propellant and decreased with increasing pressure to the 0.3 power over the range from atmospheric pressure to 250 pounds per square inch. High-speed photographs of the burning propellant surface revealed that the additives moved on the surface with the average particle velocity decreasing with pressure to approximately the 0.3 power over the pressure range from atmospheric to 50 pounds per square inch. The empirical relation between particle velocity and pressure was used to modify an agglomeration criterion presented previously. Evaluation of the critical aluminum diameter required for agglomeration indicated that both propellant types used in this study should experience some agglomeration over the pressure range studied. The aluminum size required for agglomeration was found to increase with increasing pressure. The experimental findings of the critical aluminum diameter required for agglomeration were in reasonable agreement with the calculated data. The volume mean diameter of the alumina was found to decrease with increasing pressure.

  2. Cosmopolitan distribution of the large composite microbial mat spirochete, Spirosymplokos deltaeiberi

    NASA Technical Reports Server (NTRS)

    Margulis, L.; Navarrete, A.; Sole, M.

    1998-01-01

    Inocula from organic-rich black muds immediately underlying intertidal laminated microbial mats dominated by Microcoleus chthonoplastes yielded large, variable diameter spirochetes. These unusual spirochetes, previously reported only from the Alfacs Peninsula at the delta of the Ebro river in northeast Spain, contain striking arrays of cytoplasmic granules packed into their protoplasmic cylinders. On several occasions, both in summer and winter, the huge spirochetes were recognized in samples from mats growing in the Sippewissett salt marsh at Woods Hole Massachusetts. They were also seen in similar samples from microbial mats at North Pond, Laguna Figueroa, Baja California Norte, Mexico. The identity of these spirochetes was confirmed by electron microscopy: number and disposition of flagella, composite structure, measurements of their distinctive cytoplasmic granules. The granules, larger, more conspicuous and present in addition to ribosomes, are hypothesized to contain ATPases. As culture conditions worsen, these spirochetes retract into membrane-bounded round bodies in which they form refractile inclusions. From morphology and behavior we conclude the North American spirochetes from both Atlantic and Pacific intertidal microbial mats are indistinguishable from those at the delta of the Ebro river. We conclude a cosmopolitan distribution for Spirosymplokos deltaeiberi.

  3. Effect of emissions control strategies on the size and composition distribution of urban particulate air pollution

    SciTech Connect

    Kleeman, M.J.; Cass, G.R.

    1999-01-01

    The predicted behavior of the size- and chemical-composition distribution of airborne particles in the Los Angeles area is examined as it changes in response to specific emissions control strategies. Model calculations indicate that strategies currently envisioned to control the emissions of primary particles in the Los Angeles area effectively reduce the atmospheric concentrations of particles between 0.1--0.3 {micro}m particle diameter and above 2.5 {micro}m particle diameter but do little to reduce particulate concentrations between 0.6 and 0.8 {micro}m particle diameter. Analysis reveals that in Los Angeles, most atmospheric particles with diameters between 0.6--0.8 {micro}m begin as water-soluble nonsea salt background particles over the Pacific Ocean which then are transformed by significant accumulation of gas-to-particle conversion products as they are advected across the urban area. Control of primary particulate emissions alone does not reduce the amount of secondary aerosol which forms in the atmosphere and may even serve to redistribute this secondary material to particles with diameters that scatter light more efficiently.

  4. Bacterial composition in a metropolitan drinking water distribution system utilizing different source waters.

    PubMed

    Gomez-Alvarez, Vicente; Humrighouse, Ben W; Revetta, Randy P; Santo Domingo, Jorge W

    2015-03-01

    We investigated the bacterial composition of water samples from two service areas within a drinking water distribution system (DWDS), each associated with a different primary source of water (groundwater, GW; surface water, SW) and different treatment process. Community analysis based on 16S rRNA gene clone libraries indicated that Actinobacteria (Mycobacterium spp.) and α-Proteobacteria represented nearly 43 and 38% of the total sequences, respectively. Sequences closely related to Legionella, Pseudomonas, and Vibrio spp. were also identified. In spite of the high number of sequences (71%) shared in both areas, multivariable analysis revealed significant differences between the GW and SW areas. While the dominant phylotypes where not significantly contributing in the ordination of samples, the populations associated with the core of phylotypes (1-10% in each sample) significantly contributed to the differences between both service areas. Diversity indices indicate that the microbial community inhabiting the SW area is more diverse and contains more distantly related species coexisting with local assemblages as compared with the GW area. The bacterial community structure of SW and GW service areas were dissimilar, suggesting that their respective source water and/or water quality parameters shaped by the treatment processes may contribute to the differences in community structure observed. PMID:25719474

  5. Effect of sulfate on the transformation of corrosion scale composition and bacterial community in cast iron water distribution pipes

    EPA Science Inventory

    The stability of iron corrosion products and the bacterial composition of biofilm in drinking water distribution systems (DWDS) could have great impact on the water safety at the consumer ends. In this work, pipe loops were setup to investigate the transformation characteristics ...

  6. Characteristics of aerosol size distributions and chemical compositions during wintertime pollution episodes in Beijing

    NASA Astrophysics Data System (ADS)

    Liu, Zirui; Hu, Bo; Zhang, Junke; Yu, Yangchun; Wang, Yuesi

    2016-02-01

    To characterize the features of particle pollution, continuous measurements of particle number size distributions and chemical compositions were performed at an urban site in Beijing in January 2013. The particle number and volume concentration from 14 nm to 1000 nm were (37.4 ± 15.3) × 103 cm- 3 and (85.2 ± 65.6) μm3 cm- 3, respectively. N-Ait (Aitken mode) particles dominated the number concentration, whereas N-Acc (accumulation mode) particles dominated the volume concentration. Submicron particles were generally characterized by a high content of organics and SO42 -, and a low level of NO3- and Cl-. Two types of pollution episodes were observed, characterized by the "explosive growth" (EXP) and "sustained growth" (SUS) of PM2.5. Fine particles greater than 100 nm dominated the volume concentration during the ends of these pollution episodes, shifting the maximum of the number size distribution from 60 nm to greater than 100 nm in a few hours (EXP) or a few days (SUS). Secondary transformation is the main reason for the pollution episodes; SO42 -, NO3- and NH4+ (SNA) accounted for approximately 42% (EXP) and greater than 60% (SUS) of the N-Acc particle mass increase. The size distributions of particulate organics and SNA varied on timescales of hours to days, the characteristics of which changed from bimodal to unimodal during the evolution of haze episodes. The accumulation mode (peaking at approximately 500-700 nm) was dominated by organics that appeared to be internally mixed with nitrate or sulfate. The sulfate was most likely formed via heterogeneous reactions, because the SOR was constant under dry conditions (RH < 50%) and began to increase when RH > 50%, suggesting an important contribution from heterogeneous reactions with abundant aerosol water under wet conditions. Finally, the correlations between [NO3-]/[SO42 -] and [NH4+]/[SO42 -] suggest that the homogenous reaction between HNO3 and NH3 dominated the formation of nitrate under conditions of lower aerosol acidity. Therefore, controlling the precursors of SNA will effectively help to reduce the fine particulate pollution during winter in Beijing.

  7. Community composition, distribution, and contribution of microbenthos in offshore sediments from the Yellow Sea

    NASA Astrophysics Data System (ADS)

    Meng, Zhaocui; Xu, Kuidong; Lei, Yanli

    2011-09-01

    We investigated the spatial distribution and composition of microbenthos in the seafloor sediments from 48 stations in the Yellow Sea using epifluorescence microscopy and quantitative protargol staining techniques. The bacterial abundance ranged from 2.4×10 8 to 1.9×10 9 cells cm -3 in the wet sediment, about three orders of magnitude higher than that of phototrophic (PNFs, from 6.4×10 5 to 8.8×10 6 cells cm -3) and heterotrophic nanoflagellates (HNFs, from 5.8×10 4 to 5.9×10 6 cells cm -3) and four orders of magnitude higher than that of cyanobacteria (from 2.3×10 4 to 2.3×10 6 cells cm -3) in the upper 5 cm of sediments. The abundance of diatoms varied greatly, from 3-1.1×10 5 cells cm -3 in the upper 8 cm of sediments, whereas those of heterotrophic microflagellates (HMFs, 1-182 cells cm -3) and ciliates (1-221 cells cm -3) were less varied and lower. The biomass partitioning indicates the primary importance of benthic bacteria (50.3 μg C cm -3 on average), followed by PNFs (40.7 μg C cm -3), HNFs (19.3 μg C cm -3), and finally by cyanobacteria (8.8 μg C cm -3). Benthic diatoms (0.8 μg C cm -3), ciliates (0.15 μg C cm -3), and HMFs (0.03 μg C cm -3) contribute relatively small fractions to the total biomass of the microbenthos. About 95% of diatoms, 77% of ciliates, and 56% of HMFs were distributed in the upper 2 cm of sediments, whereas no distinct vertical distributions were observed for bacteria, cyanobacteria, PNFs, and HNFs. The microbenthos are quantitatively important in the shallow seafloor, wherein their main components have an average abundance three orders of magnitude higher than the corresponding planktonic organisms in the same sea area. Our estimates indicate that pico-sized phytobenthos might contribute a large proportion to the primary production. Benthic ciliates and heterotrophic flagellates contribute about 90% to the estimated combined metabolic rate of micro- and meiobenthic consumers in the whole sea area, with nanoheterotrophs accounting for the majority. The data suggest the potential for the rapid primary and secondary production of microbenthos and detrital utilization in the shallow seafloor sediments of the Yellow Sea.

  8. On the chemical state and distribution of Zr- and V-based additives in reactive hydride composites

    NASA Astrophysics Data System (ADS)

    Bösenberg, U.; Vainio, U.; Pranzas, P. K.; Bellosta von Colbe, J. M.; Goerigk, G.; Welter, E.; Dornheim, M.; Schreyer, A.; Bormann, R.

    2009-05-01

    Reactive hydride composites (RHCs) are very promising hydrogen storage materials for future applications due to their reduced reaction enthalpies and high gravimetric capacities. At present, the materials' functionality is limited by the reaction kinetics. A significant positive influence can be observed with addition of transition-metal-based additives. To understand the effect of these additives, the chemical state and changes during the reaction as well as the microstructural distribution were investigated using x-ray absorption near-edge structure (XANES) spectroscopy and anomalous small-angle x-ray scattering (ASAXS). In this work, zirconium- and vanadium-based additives were added to 2LiBH4-MgH2 composites and 2LiH-MgB2 composites and measured in the vicinity of the corresponding absorption edge. The measurements reveal the formation of finely distributed zirconium diboride and vanadium-based nanoparticles. The potential mechanisms for the observed influence on the reaction kinetics are discussed.

  9. Structural Health Monitoring of Composite Materials Using Distributed Fiber Bragg Sensors

    NASA Technical Reports Server (NTRS)

    Grant, Joseph; Kual, Raj; Taylor, Scott; Jackson, Kurt V.; Myers, George; Wang, Y.; Sharma, A.; Burdine, Robert (Technical Monitor)

    2002-01-01

    Health monitoring of polymer matrix composite materials using fiber optic Bragg grating (FBG) sensors is accomplished using a tunable IR (infrared) laser via transmission mode. Results are presented from experiments of composite structures with FBG's embedded at various orientations, and surface measurements of various cryogenic composite vessels.

  10. A STUDY ON TEMPORAL DISTRIBUTION OF FREIGHT TRANSPORTATION IN CONSIDERATION OF DAILY WORK-LIFE CYCLE

    NASA Astrophysics Data System (ADS)

    Kitaoka, Daiki; Hara, Hidetaka; Oeda, Yoshinao; Sumi, Tomonori

    As advanced freight service is demanded, the time related requirements fo r freight transportation becomes more and more significant. This study, focusing on temporal distribution of freight transportation responding to the travel time, developed a shipment departure time decision model for each item, aiming at quantitatively grasping social requirement in the time domain. The model takes account of the daily work cycle of both work cy cles of shippers and carriers along with the travel time. The proposed model has a similar structure as that derived from the previous studies taking account of the daily living cycle of individuals. This model properly reproduced temporal distribution of shipment departure time that changes depending on the length of necessary lead time for each item.

  11. Anchovy shelf life as affected by different chilling methods during distribution.

    PubMed

    Careche, Mercedes; Garca, Raul; Borderas, Javier

    2002-02-01

    Anchovies are a very labile fish and deteriorate fast under chilling conditions. In the South of Spain, fishing boats land their catches in wooden boxes with ice (12 to 14 kg). For some years now, fish processors have prepared this species for market distribution by placing about 7 kg fish in expanded polystyrene (EPS) boxes containing water and ice. Then, in the distribution market, boxes are dewatered and re-iced. Transportation of the fish in EPS boxes containing water and ice was recently forbidden on the grounds that boxes for transportation of fish in ice must have holes to let melted ice drain away. In this paper, the effect of preserving the anchovy in water and ice from landing to the distribution market was studied and compared with the more traditional methods of storing the fish in ice in either wooden or EPS boxes. Physical, chemical, microbiological, and sensory analyses were carried out over three different storage trials to account for the effect of seasonality. Little differences were found among lots, but some of the parameters showed that fish transported in water and ice did present less spoilage than fish stored in ice, especially when compared to the wooden boxes. According to these results, chilling of this fish in water and ice can be used as an alternative preserving method during transport. PMID:11848567

  12. Biology, Systematics, Life Cycle, and Distribution of Angiostrongylus cantonensis, the Cause of Rat Lungworm Disease

    PubMed Central

    2013-01-01

    Angiostrongylus cantonensis is a metastrongyloid nematode in the family Angiostrongylidae. It is the cause of angiostrongyliasis (rat lungworm disease), which manifests as eosinophilic meningitis. First described in 1935 from rats in China, A. cantonensis was placed in the genus Parastrongylus in 1986, but most workers have not adopted this treatment. The taxonomy of A. cantonensis and related worms is largely based on adult morphology, notably of the male bursa. However, identification of infective third stage larvae is more difficult. The natural life cycle involves rats as the definitive host and snails or slugs as the intermediate host. Human infection, as accidental hosts, results in worms maturing in the brain, but dying there instead of moving back into the bloodstream, as in rats, thereby leading to eosinophilic meningitis. The disease is an emerging infectious disease; Angiostrongylus cantonensis continues to be reported in new regions beyond its native range. PMID:23901372

  13. The LifeWatch approach to the exploration of distributed species information

    PubMed Central

    Fuentes, Daniel; Fiore, Nicola

    2014-01-01

    Abstract This paper introduces a new method of automatically extracting, integrating and presenting information regarding species from the most relevant online taxonomic resources. First, the information is extracted and joined using data wrappers and integration solutions. Then, an analytical tool is used to provide a visual representation of the data. The information is then integrated into a user friendly content management system. The proposal has been implemented using data from the Global Biodiversity Information Facility (GBIF), the Catalogue of Life (CoL), the World Register of Marine Species (WoRMS), the Integrated Taxonomic Information System (ITIS) and the Global Names Index (GNI). The approach improves data quality, avoiding taxonomic and nomenclature errors whilst increasing the availability and accessibility of the information. PMID:25589865

  14. Biology, systematics, life cycle, and distribution of Angiostrongylus cantonensis, the cause of rat lungworm disease.

    PubMed

    Cowie, Robert H

    2013-06-01

    Angiostrongylus cantonensis is a metastrongyloid nematode in the family Angiostrongylidae. It is the cause of angiostrongyliasis (rat lungworm disease), which manifests as eosinophilic meningitis. First described in 1935 from rats in China, A. cantonensis was placed in the genus Parastrongylus in 1986, but most workers have not adopted this treatment. The taxonomy of A. cantonensis and related worms is largely based on adult morphology, notably of the male bursa. However, identification of infective third stage larvae is more difficult. The natural life cycle involves rats as the definitive host and snails or slugs as the intermediate host. Human infection, as accidental hosts, results in worms maturing in the brain, but dying there instead of moving back into the bloodstream, as in rats, thereby leading to eosinophilic meningitis. The disease is an emerging infectious disease; Angiostrongylus cantonensis continues to be reported in new regions beyond its native range. PMID:23901372

  15. Physical and biological control of protistan community composition, distribution and abundance in the seasonal ice zone of the Southern Ocean between 30 and 80°E

    NASA Astrophysics Data System (ADS)

    Davidson, Andrew T.; Scott, Fiona J.; Nash, Geraldine V.; Wright, Simon W.; Raymond, Ben

    2010-05-01

    Protists are critical components of the Antarctic marine ecosystem as they comprise most of the living carbon and are the base of the Antarctic food web. They are also key determinants of vertical carbon flux and mediate draw-down of atmospheric CO 2 by the ocean. The community composition, abundance and distribution of marine protists (phytoplankton and protozoa) was studied during the Baseline Research on Oceanography, Krill and the Environment-West (BROKE-West) survey, in the seasonal ice zone during the 2005-2006 austral summer between 30°E and 80°E. Light and electron microscopy were used to determine the protistan composition and abundance in samples obtained at 30 sites from surface waters and at 26 sites from the depth of the maximum in situ chlorophyll fluorescence (Chl max). Cluster analysis was used to identify 5 groups of sample sites at the surface and 5 at the Chl max that were of similar protist composition and abundance. The physical characteristics, taxonomic composition, indicator taxa, and taxonomic diversity were determined for each group. In the southwest, a bloom of colonial Phaeocystis antarctica dominated the protistan community composition and biomass amongst the receding ice, but this was replaced by the flagellate life stage/s of this haptophyte in waters to the north. In the southeast, a diatom bloom had the highest diversity of protist taxa observed during the survey and centric diatoms dominated the biomass. Outside these blooms, grazing by krill probably reduced the composition and abundance of large diatoms and autotrophic dinoflagellates in coastal to mid-inshore waters. Only in offshore waters did large diatoms and dinoflagellates increase in abundance and diversity, despite low concentrations of iron and silicate at many of these sites. This increase was probably due to reduced top-down control by krill and other large zooplankton. Large diatoms dominated in offshore waters, despite other coincident studies showing that the trophic structure and function of the microbial community was frequently typical of nanoflagellate-dominated systems in high-nutrient low-chlorophyll waters. Nanoflagellate abundances were low during the survey and were either poorly resolved by our study or limited by microheterotrophic grazing. We propose that protistan abundance and composition in the sea-ice zone of the Indian Sector were determined by synoptic-scale oceanographic features, meso-scale changes caused by sea-ice retreat and meso- to nano- scale interactions between grazers and the composition and abundance of their protistan prey.

  16. The Ichthyoplankton of Selected Estuaries in Sarawak and Sabah: Composition, Distribution and Habitat Affinities

    NASA Astrophysics Data System (ADS)

    Blaber, S. J. M.; Farmer, M. J.; Milton, D. A.; Pang, J.; Boon-Teck, O.; Wong, P.

    1997-08-01

    The ichthyoplankton assemblages of 23 estuaries in Sarawak and Sabah were surveyed with particular reference to the culturally and commercially important clupeid Tenualosa toli. The species composition, distribution and density of all fish larvae were recorded, together with the physical characteristics of each estuary. A more detailed study was made of the Lupar and Lassa estuaries, which are the ' core area ' for T. toli. The estuaries fall into two groups. The first consists of the estuaries of the ' core area ' from the Sebako in the west to the Lassa in the east, and the Labuk and Kinabatangan estuaries of eastern Sabah. They are large and deep, have middle-range salinities with no halocline, are highly turbid and have tidal ranges of >3·5 m and strong currents. There is little seasonal change in freshwater input and their waters are not peat-stained. Their total zooplankton biomasses (approximately 0·05 g m -3dry weight, excluding fish larvae) are an order of magnitude greater than biomasses in the second group of estuaries. The second group consists of all estuaries east of the Lassa as far as the Papar in Sabah. They are mostly smaller, shallower and have more variable salinities than the ' core area ' estuaries, with marked haloclines and seasonal changes in freshwater inflow, lower turbidities, weaker currents, tidal ranges of <2 m and low overall zooplankton biomasses. The composition of the ichthyoplankton is different in these two groups of estuaries. The assemblage in the first group (' core area ') of estuaries consists primarily of taxa associated with estuarine and/or turbid water conditions, whereas those in the smaller estuaries of the second group have mainly marine and clearer water affinities. Only the Gobiidae are ubiquitous. Very few larvae of freshwater species were recorded in any of the estuaries. The number of fish larvae was highly variable, but the mean densities (0·01-9·23 m -3) were similar, and similarly variable, to the densities reported for other tropical estuaries. The diversity of the ichthyoplankton assemblage in Sarawak and Sabah estuaries (56 taxa, 26 families) is lower than in most other tropical estuaries of the Indo-west Pacific. This is possibly because of their rigorous physical nature, particularly the very high turbidities and current speeds, or in smaller, less physically rigorous estuaries, the low biomass of zooplankton available as food for the larvae.

  17. Size-, surface- and crystalline structure composition-related effects of titanium dioxide nanoparticles during their aquatic life cycle.

    PubMed

    Seitz, Frank; Rosenfeldt, Ricki R; Schneider, Sandra; Schulz, Ralf; Bundschuh, Mirco

    2014-09-15

    Nanoparticle toxicity depends amongst others on particle characteristics and nanoparticle behavior during their aquatic life cycle. Aquatic organisms may be exposed to nanoparticle agglomerates of varying size, while lager agglomerates after settling rather affect benthic organisms. In this context, the present study systematically examined the role of particle characteristics, i.e. crystalline structure composition (anatase as well as mixture of anatase-rutile), initial particle size (55-, 100-, and 140-nm) and surface area, in the toxicity of titanium dioxide nanoparticles (nTiO2) to the pelagic filter feeder Daphnia magna (n = 4) and the benthic amphipod Gammarus fossarum (n = 30). Smaller initial particle sizes (i.e. 55-nm) and anatase based particles showed an approximately 90% lower Daphnia EC50-value compared to its respective counterpart. Most importantly, particle surface normalized EC50-values significantly differed for nanoparticles equal to or below 100 nm in size from 140-nm sized particles. Hence, these data suggest that the reactive initial surface area may explain the ecotoxicological potential of different particle size classes only if their size is smaller or around 100 nm. In contrast to Daphnia, Gammarus was not affected by nTiO2 concentrations of up to 5.00 mg/L, irrespective of their characteristics. This indicates fundamental differences in the toxicity of nTiO2 during its aquatic life cycle mediated by alterations in their characteristics over time. PMID:25010941

  18. Design, fabrication, and properties of 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution

    PubMed Central

    Dongyu, Xu; Xin, Cheng; Banerjee, Sourav; Shifeng, Huang

    2014-01-01

    The laminated 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramic as active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction of piezoelectric phase have large piezoelectric strain constant and relative permittivity, and the piezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction of piezoelectric phase have large piezoelectric voltage constant, but also large dielectric loss. The composite with gradually increased dimension of piezoelectric ceramic layer has the smallest dielectric loss, and that with the gradually increased dimension of matrix layer has the largest piezoelectric voltage constant. The novel piezoelectric composites show potential applications in fabricating ultrasonic transducers with varied surface vibration amplitude of the transducer. PMID:25565725

  19. Design, fabrication, and properties of 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution

    SciTech Connect

    Dongyu, Xu; Xin, Cheng; Shifeng, Huang; Banerjee, Sourav

    2014-12-28

    The laminated 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramic as active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction of piezoelectric phase have large piezoelectric strain constant and relative permittivity, and the piezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction of piezoelectric phase have large piezoelectric voltage constant, but also large dielectric loss. The composite with gradually increased dimension of piezoelectric ceramic layer has the smallest dielectric loss, and that with the gradually increased dimension of matrix layer has the largest piezoelectric voltage constant. The novel piezoelectric composites show potential applications in fabricating ultrasonic transducers with varied surface vibration amplitude of the transducer.

  20. Antarctic Marine Biodiversity – What Do We Know About the Distribution of Life in the Southern Ocean?

    PubMed Central

    Griffiths, Huw J.

    2010-01-01

    The remote and hostile Southern Ocean is home to a diverse and rich community of life that thrives in an environment dominated by glaciations and strong currents. Marine biological studies in the region date back to the nineteenth century, but despite this long history of research, relatively little is known about the complex interactions between the highly seasonal physical environment and the species that inhabit the Southern Ocean. Oceanographically, the Southern Ocean is a major driver of global ocean circulation and plays a vital role in interacting with the deep water circulation in each of the Pacific, Atlantic, and Indian oceans. The Census of Antarctic Marine Life and the Scientific Committee on Antarctic Research Marine Biodiversity Information Network (SCAR-MarBIN) have strived to coordinate and unify the available scientific expertise and biodiversity data to improve our understanding of Southern Ocean biodiversity. Taxonomic lists for all marine species have been compiled to form the Register of Antarctic Marine Species, which currently includes over 8,200 species. SCAR-MarBIN has brought together over 1 million distribution records for Southern Ocean species, forming a baseline against which future change can be judged. The sample locations and numbers of known species from different regions were mapped and the depth distributions of benthic samples plotted. Our knowledge of the biodiversity of the Southern Ocean is largely determined by the relative inaccessibility of the region. Benthic sampling is largely restricted to the shelf; little is known about the fauna of the deep sea. The location of scientific bases heavily influences the distribution pattern of sample and observation data, and the logistical supply routes are the focus of much of the at-sea and pelagic work. Taxa such as mollusks and echinoderms are well represented within existing datasets with high numbers of georeferenced records. Other taxa, including the species-rich nematodes, are represented by just a handful of digital records. PMID:20689841

  1. Antarctic marine biodiversity--what do we know about the distribution of life in the Southern Ocean?

    PubMed

    Griffiths, Huw J

    2010-01-01

    The remote and hostile Southern Ocean is home to a diverse and rich community of life that thrives in an environment dominated by glaciations and strong currents. Marine biological studies in the region date back to the nineteenth century, but despite this long history of research, relatively little is known about the complex interactions between the highly seasonal physical environment and the species that inhabit the Southern Ocean. Oceanographically, the Southern Ocean is a major driver of global ocean circulation and plays a vital role in interacting with the deep water circulation in each of the Pacific, Atlantic, and Indian oceans. The Census of Antarctic Marine Life and the Scientific Committee on Antarctic Research Marine Biodiversity Information Network (SCAR-MarBIN) have strived to coordinate and unify the available scientific expertise and biodiversity data to improve our understanding of Southern Ocean biodiversity. Taxonomic lists for all marine species have been compiled to form the Register of Antarctic Marine Species, which currently includes over 8,200 species. SCAR-MarBIN has brought together over 1 million distribution records for Southern Ocean species, forming a baseline against which future change can be judged. The sample locations and numbers of known species from different regions were mapped and the depth distributions of benthic samples plotted. Our knowledge of the biodiversity of the Southern Ocean is largely determined by the relative inaccessibility of the region. Benthic sampling is largely restricted to the shelf; little is known about the fauna of the deep sea. The location of scientific bases heavily influences the distribution pattern of sample and observation data, and the logistical supply routes are the focus of much of the at-sea and pelagic work. Taxa such as mollusks and echinoderms are well represented within existing datasets with high numbers of georeferenced records. Other taxa, including the species-rich nematodes, are represented by just a handful of digital records. PMID:20689841

  2. Maternal nutrition, fetal weight, body composition and disease in later life.

    PubMed

    Zadik, Z

    2003-09-01

    Nutritional and hormonal milieu in utero affect fetal growth. Both parties involved have an independent chance, for the occurrence of a developmental error at any stage of their constant developing system. Studies suggest that pregnancy outcome is associated with fetal demand for nutrients and the materno-placental capacity to meet that demand. Failure of the materno-placental supply line to satisfy fetal nutrient requirements results in a range of fetal adaptations and developmental changes, and may lead to permanent alterations in the body's structure and metabolism, and thereby to cardiovascular and metabolic disease in adult life. Changes in the in-utero homeostasis may lead to programming of endocrine and metabolic systems so that feedback systems and reactions are permanently changed. At the present stage, short- and long-term hazards of intra-uterine growth retardation (IUGR) have been identified, but preventive strategies are still lacking. It is unlikely that a single factor will reduce a multi-causal outcome like IUGR. Appropriate population-specific interventions should be a priority. PMID:14964450

  3. Undernutrition during early life alters neuropeptide Y distribution along the arcuate/paraventricular pathway.

    PubMed

    Rocha, M L M; Fernandes, P P; Lotufo, B M; Manhães, A C; Barradas, P C; Tenorio, F

    2014-01-01

    Perinatal nutrient restriction exerts profound influences on brain development. Animals that suffer undernutrition during lactation also display impaired weight gain. Feeding behavior is mainly modulated by neural and hormonal inputs to the hypothalamus. The arcuate-paraventricular neuropeptidergic Y pathway has a prominent role in appetite regulation. The aim of this work was to study the effects of protein undernutrition during lactation on this hypothalamic pathway. We used rats from 5 to 60 postnatal (P) days whose dams were fed a 0% protein diet (PFG) or a normoprotein diet (CG) from P1 to P10. To reproduce the same amount of calorie ingested by the PFG we used an underfed group (UFG). Immunohistochemistry was performed to assess neuropeptide Y (NPY) distribution in the arcuate, periventricular and paraventricular nuclei. Our results showed a NPY immunostaining peak at P10 in all nuclei in CG animals. In UFG animals this peak was observed by P15, while, in the PFG animals only by P20. Our results suggest that the neuropeptidergic arcuate-paraventricular pathway suffered a delay in NPY distribution in undernourished animals, particularly those fed a 0% protein diet, reflecting an effect on this pathway maturation that could explain previously reported alterations on feeding behavior in these animals. PMID:24183962

  4. Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast

    NASA Astrophysics Data System (ADS)

    Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

    2008-12-01

    Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol particles, suggesting the impacts of different sources on the particle-size distributions of atmospheric iron. More results will be discussed during the presentation at the meeting.

  5. Tracing organic matter composition and distribution and its role on arsenic release in shallow Cambodian groundwaters

    NASA Astrophysics Data System (ADS)

    Lawson, Michael; Polya, David A.; Boyce, Adrian J.; Bryant, Charlotte; Ballentine, Christopher J.

    2016-04-01

    Biogeochemical processes that utilize dissolved organic carbon are widely thought to be responsible for the liberation of arsenic from sediments to shallow groundwater in south and southeast Asia. The accumulation of this known carcinogen to hazardously high concentrations has occurred in the primary source of drinking water in large parts of densely populated countries in this region. Both surface and sedimentary sources of organic matter have been suggested to contribute dissolved organic carbon in these aquifers. However, identification of the source of organic carbon responsible for driving arsenic release remains enigmatic and even controversial. Here, we provide the most extensive interrogation to date of the isotopic signature of ground and surface waters at a known arsenic hotspot in Cambodia. We present tritium and radiocarbon data that demonstrates that recharge through ponds and/or clay windows can transport young, surface derived organic matter into groundwater to depths of 44 m under natural flow conditions. Young organic matter dominates the dissolved organic carbon pool in groundwater that is in close proximity to these surface water sources and we suggest this is likely a regional relationship. In locations distal to surface water contact, dissolved organic carbon represents a mixture of both young surface and older sedimentary derived organic matter. Ground-surface water interaction therefore strongly influences the average dissolved organic carbon age and how this is distributed spatially across the field site. Arsenic mobilization rates appear to be controlled by the age of dissolved organic matter present in these groundwaters. Arsenic concentrations in shallow groundwaters (<20 m) increase by 1 μg/l for every year increase in dissolved organic carbon age compared to only 0.25 μg/l for every year increase in dissolved organic carbon age in deeper (>20 m) groundwaters. We suggest that, while the rate of arsenic release is greatest in shallow aquifer sediments, arsenic release also occurs in deeper aquifer sediments and as such remains an important process in controlling the spatial distribution of arsenic in the groundwaters of SE Asia. Our findings suggest that any anthropogenic activities that alter the source of groundwater recharge or the timescales over which recharge takes place may also drive changes in the natural composition of dissolved organic carbon in these groundwaters. Such changes have the potential to influence both the spatial and temporal evolution of the current groundwater arsenic hazard in this region.

  6. Feeding into old age: long-term effects of dietary fatty acid supplementation on tissue composition and life span in mice

    PubMed Central

    Ruf, Thomas

    2010-01-01

    Smaller mammals, such as mice, possess tissues containing more polyunsaturated fatty acids (PUFAs) than larger mammals, while at the same time live shorter lives. These relationships have been combined in the ‘membrane pacemaker hypothesis of aging’. It suggests that membrane PUFA content might determine an animal’s life span. PUFAs in general and certain long-chain PUFAs in particular, are highly prone to lipid peroxidation which brings about a high rate of reactive oxygen species (ROS) production. We hypothesized that dietary supplementation of either n-3 or n-6 PUFAs might affect (1) membrane phospholipid composition of heart and liver tissues and (2) life span of the animals due to the altered membrane composition, and subsequent effects on lipid peroxidation. Therefore, we kept female laboratory mice from the C57BL/6 strain on three diets (n-3 PUFA rich, n-6 PUFA rich, control) and assessed body weights, life span, heart, and liver phospholipid composition after the animals had died. We found that while membrane phospholipid composition clearly differed between feeding groups, life span was not directly affected. However, we were able to observe a positive correlation between monounsaturated fatty acids in cardiac muscle and life span. PMID:20981551

  7. Vertical distribution of triple oxygen isotopic composition of dissolved oxygen in the northwestern Pacific

    NASA Astrophysics Data System (ADS)

    Abe, Osamu; Honda, Makio; Saino, Toshiro

    2013-04-01

    Oxygen-17 excess of dissolved oxygen calculated from δ18O and δ17O is not affected by oxygen consumption process but controlled only by processes of primary production and air-water gas transfer. Evaluating gross primary productivity using the 17O-excess in ocean surface water are one of the most advanced geochemical researches for last 10 years. Oxygen-17 excess below ocean mixed/photic layer has not been much investigated because it might be out of focus for estimating present primary productivity, except for the purpose to correct diapycnal mixing effect on surface water. In principle, water mass which has not been affected both by photosynthesis and gas transfer after its separation from ocean surface could preserve 17O-excess value where the water mass was at the surface. The purpose of this study is to determine the vertical distribution of 17O-excess from the surface to the bottom of northwestern Pacific to know whether 17O-excess could really preserve its "original" value after the long and dark travel. Near stations K2 and KNOT, water mass which has a density of 26.8 ?? is observed at depth between 100 and 300 m. This water mass is mainly originated from bottom water in the Okhotsk Sea and spreading widely to entire northwestern Pacific, which is called North Pacific Intermediate Water (NPIW). NPIW is found at depth of 700 m at station S1. Samplings were conducted by two R/V Mirai cruises (MR10-06, Oct-Nov 2010; MR11-02, Feb-Mar 2011). Dissolved oxygen gas was purified by the method of Sarma et al. (2003) and its isotopic composition was determined by dual-inlet isotope ratio mass spectrometer (Thermo Scientific Delta Plus). Gross primary productivities at mixed layer estimated by 17O-excess were well consistent with those by conventional light and dark bottle incubations for stations K2 and S1.

  8. Monitoring of Pb Contamination in Loire Estuary: Trends, Distribution and Isotopic composition

    NASA Astrophysics Data System (ADS)

    Brach-Papa, Christophe; Chiffoleau, Jean-François; Knoery, Joel; Chouvelon, Tiphaine; Auger, Dominique; Bretaudeau, Jane; Crochet, Sylvette; Rozuel, Emmanuelle; Thomas, Batien; Vasileva, Emilia; Oriani, Anna Maria

    2014-05-01

    The Loire River is one of the largest river systems in Western Europe and constitutes a major continental input to marine environment in the Bay of Biscay. Its catchment area flows through agricultural, industrial areas and through a more and more urbanized estuary. Even if Loire River is not considered as a highly polluted system, some studies identified a Pb contamination of its estuary due to industrial inputs and combustion of leaded gasoline up to the mid 90's. A retrospective study, based on the analysis (Pb contents and isotopic composition) of Mytilus edulis samples collected by the French mussel watch program (RNO/ROCCH) has highlighted this contamination and its trend between 1985-2005 (Couture et al., 2010). This poster will first complete the work initiated by Couture et al. Pb contents and isotopic signatures in mussel samples collected by RNO/ROCCH over the last 10 years will be presented and discussed. Results will be compared to measurements performed on various environmental samples (sediment, biota…) collected in the frame of the environmental monitoring project RS2E started in 2012 by the "Observatoire des Sciences de l'Univers Nantes-Atlantique" (OSUNA). This new data will contribute to a better characterisation of Pb contents and distribution along the Loire Estuary. Moreover, some key samples will be submitted to HR-ICP-MS for Pb isotopic analysis. Discrimination of anthropic Pb sources requires both precise and accurate isotope ratio determination and also high versatility due to the complex matrix, which is typical for marine and estuarine samples. These measurements will contribute to a more accurate definition and characterisation of main actual anthropic Pb sources (urban, agricultural, industrial or atmospheric deposition). Couture R.- M., Chiffoleau J.-F., Auger D., Claisse D., Gobeil C. and Cossa D. (2010) Seasonal and decadal variation in lead sources to eastern north Atlantic mussels. Environ. Sci. Technol. 44, 1211-1216.

  9. Fibrosis in Human Adipose Tissue: Composition, Distribution, and Link With Lipid Metabolism and Fat Mass Loss

    PubMed Central

    Divoux, Adeline; Tordjman, Joan; Lacasa, Danièle; Veyrie, Nicolas; Hugol, Danielle; Aissat, Abdelhalim; Basdevant, Arnaud; Guerre-Millo, Michèle; Poitou, Christine; Zucker, Jean-Daniel; Bedossa, Pierre; Clément, Karine

    2010-01-01

    OBJECTIVE Fibrosis is a newly appreciated hallmark of the pathological alteration of human white adipose tissue (WAT). We investigated the composition of subcutaneous (scWAT) and omental WAT (oWAT) fibrosis in obesity and its relationship with metabolic alterations and surgery-induced weight loss. RESEARCH DESIGN AND METHODS Surgical biopsies for scWAT and oWAT were obtained in 65 obese (BMI 48.2 ± 0.8 kg/m2) and 9 lean subjects (BMI 22.8 ± 0.7 kg/m2). Obese subjects who were candidates for bariatric surgery were clinically characterized before, 3, 6, and 12 months after surgery, including fat mass evaluation by dual energy X-ray absorptiometry. WAT fibrosis was quantified and characterized using quantitative PCR, microscopic observation, and immunohistochemistry. RESULTS Fibrosis amount, distribution and collagen types (I, III, and VI) present distinct characteristics in lean and obese subjects and with WAT depots localization (subcutaneous or omental). Obese subjects had more total fibrosis in oWAT and had more pericellular fibrosis around adipocytes than lean subjects in both depots. Macrophages and mastocytes were highly represented in fibrotic bundles in oWAT, whereas scWAT was more frequently characterized by hypocellular fibrosis. The oWAT fibrosis negatively correlated with omental adipocyte diameters (R = −0.30, P = 0.02), and with triglyceride levels (R = −0.42, P < 0.01), and positively with apoA1 (R = 0.25, P = 0.05). Importantly, scWAT fibrosis correlated negatively with fat mass loss measured at the three time points after surgery. CONCLUSIONS Our data suggest differential clinical consequences of fibrosis in human WAT. In oWAT, fibrosis could contribute to limit adipocyte hypertrophy and is associated with a better lipid profile, whereas scWAT fibrosis may hamper fat mass loss induced by surgery. PMID:20713683

  10. Distribution of protein poly(ADP-ribosyl)ation systems across all domains of life

    PubMed Central

    Perina, Dragutin; Mikoč, Andreja; Ahel, Josip; Ćetković, Helena; Žaja, Roko; Ahel, Ivan

    2014-01-01

    Poly(ADP-ribosyl)ation is a post-translational modification of proteins involved in regulation of many cellular pathways. Poly(ADP-ribose) (PAR) consists of chains of repeating ADP-ribose nucleotide units and is synthesized by the family of enzymes called poly(ADP-ribose) polymerases (PARPs). This modification can be removed by the hydrolytic action of poly(ADP-ribose) glycohydrolase (PARG) and ADP-ribosylhydrolase 3 (ARH3). Hydrolytic activity of macrodomain proteins (MacroD1, MacroD2 and TARG1) is responsible for the removal of terminal ADP-ribose unit and for complete reversion of protein ADP-ribosylation. Poly(ADP-ribosyl)ation is widely utilized in eukaryotes and PARPs are present in representatives from all six major eukaryotic supergroups, with only a small number of eukaryotic species that do not possess PARP genes. The last common ancestor of all eukaryotes possessed at least five types of PARP proteins that include both mono and poly(ADP-ribosyl) transferases. Distribution of PARGs strictly follows the distribution of PARP proteins in eukaryotic species. At least one of the macrodomain proteins that hydrolyse terminal ADP-ribose is also always present. Therefore, we can presume that the last common ancestor of all eukaryotes possessed a fully functional and reversible PAR metabolism and that PAR signalling provided the conditions essential for survival of the ancestral eukaryote in its ancient environment. PARP proteins are far less prevalent in bacteria and were probably gained through horizontal gene transfer. Only eleven bacterial species possess all proteins essential for a functional PAR metabolism, although it is not known whether PAR metabolism is truly functional in bacteria. Several dsDNA viruses also possess PARP homologues, while no PARP proteins have been identified in any archaeal genome. Our analysis of the distribution of enzymes involved in PAR metabolism provides insight into the evolution of these important signalling systems, as well as providing the basis for selection of the appropriate genetic model organisms to study the physiology of the specific human PARP proteins. PMID:24865146

  11. Bayesian statistical approaches to compositional analyses of transgenic crops 2. Application and validation of informative prior distributions.

    PubMed

    Harrison, Jay M; Breeze, Matthew L; Berman, Kristina H; Harrigan, George G

    2013-03-01

    Bayesian approaches to evaluation of crop composition data allow simpler interpretations than traditional statistical significance tests. An important advantage of Bayesian approaches is that they allow formal incorporation of previously generated data through prior distributions in the analysis steps. This manuscript describes key steps to ensure meaningful and transparent selection and application of informative prior distributions. These include (i) review of previous data in the scientific literature to form the prior distributions, (ii) proper statistical model specification and documentation, (iii) graphical analyses to evaluate the fit of the statistical model to new study data, and (iv) sensitivity analyses to evaluate the robustness of results to the choice of prior distribution. The validity of the prior distribution for any crop component is critical to acceptance of Bayesian approaches to compositional analyses and would be essential for studies conducted in a regulatory setting. Selection and validation of prior distributions for three soybean isoflavones (daidzein, genistein, and glycitein) and two oligosaccharides (raffinose and stachyose) are illustrated in a comparative assessment of data obtained on GM and non-GM soybean seed harvested from replicated field sites at multiple locations in the US during the 2009 growing season. PMID:23261475

  12. Deformation and Life Analysis of Composite Flywheel Disk and Multi-disk Systems

    NASA Technical Reports Server (NTRS)

    Arnold, S. M.; Saleeb, A. F.; AlZoubi, N. R.

    2001-01-01

    In this study an attempt is made to put into perspective the problem of a rotating disk, be it a single disk or a number of concentric disks forming a unit. An analytical model capable of performing an elastic stress analysis for single/multiple, annular/solid, anisotropic/isotropic disk systems, subjected to both pressure surface tractions, body forces (in the form of temperature-changes and rotation fields) and interfacial misfits is derived and discussed. Results of an extensive parametric study are presented to clearly define the key design variables and their associated influence. In general the important parameters were identified as misfit, mean radius, thickness, material property and/or load gradation, and speed; all of which must be simultaneously optimized to achieve the "best" and most reliable design. Also, the important issue of defining proper performance/merit indices (based on the specific stored energy), in the presence of multiaxiality and material anisotropy is addressed. These merit indices are then utilized to discuss the difference between flywheels made from PMC and TMC materials with either an annular or solid geometry. Finally two major aspects of failure analysis, that is the static and cyclic limit (burst) speeds are addressed. In the case of static limit loads, upper, lower, and out-of-plane bounds for disks with constant thickness are presented for both the case of internal pressure loading (as one would see in a hydroburst test) and pure rotation (as in the case of a free spinning disk). The results (interaction diagrams) are displayed graphically in designer friendly format. For the case of fatigue, a representative fatigue/life master curve is illustrated in which the normalized limit speed versus number of applied cycles is given for a cladded TMC disk application.

  13. Glass Composition Constraint Recommendations for Use in Life-Cycle Mission Modeling

    SciTech Connect

    McCloy, John S.; Vienna, John D.

    2010-05-03

    The component concentration limits that most influence the predicted Hanford life-cycle HLW glass volume by HTWOS were re-evaluated. It was assumed that additional research and development work in glass formulation and melter testing would be performed to improve the understanding of component effects on the processability and product quality of these HLW glasses. Recommendations were made to better estimate the potential component concentration limits that could be applied today while technology development is underway to best estimate the volume of HLW glass that will eventually be produced at Hanford. The limits for concentrations of P2O5, Bi2O3, and SO3 were evaluated along with the constraint used to avoid nepheline formation in glass. Recommended concentration limits were made based on the current HLW glass property models being used by HTWOS (Vienna et al. 2009). These revised limits are: 1) The current ND should be augmented by the OB limit of OB ≤ 0.575 so that either the normalized silica (NSi) is less that the 62% limit or the OB is below the 0.575 limit. 2) The mass fraction of P2O5 limit should be revised to allow for up to 4.5 wt%, depending on CaO concentrations. 3) A Bi2O3 concentration limit of 7 wt% should be used. 4) The salt accumulation limit of 0.5 wt% SO3 may be increased to 0.6 wt%. Again, these revised limits do not obviate the need for further testing, but make it possible to more accurately predict the impact of that testing on ultimate HLW glass volumes.

  14. Europa's Crust and Ocean: Origin, Composition, and the Prospects for Life

    USGS Publications Warehouse

    Kargel, J.S.; Kaye, J.Z.; Head, J. W., III; Marion, G.M.; Sassen, R.; Crowley, J.K.; Ballesteros, O.P.; Grant, S.A.; Hogenboom, D.L.

    2000-01-01

    We have considered a wide array of scenarios for Europa's chemical evolution in an attempt to explain the presence of ice and hydrated materials on its surface and to understand the physical and chemical nature of any ocean that may lie below. We postulate that, following formation of the jovian system, the europan evolutionary sequence has as its major links: (a) initial carbonaceous chondrite rock, (b) global primordial aqueous differentiation and formation of an impure primordial hydrous crust, (c) brine evolution and intracrustal differentiation, (d) degassing of Europa's mantle and gas venting, (e) hydrothermal processes, and (f) chemical surface alteration. Our models were developed in the context of constraints provided by Galileo imaging, near infrared reflectance spectroscopy, and gravity and magnetometer data. Low-temperature aqueous differentiation from a carbonaceous CI or CM chondrite precursor, without further chemical processing, would result in a crust/ocean enriched in magnesium sulfate and sodium sulfate, consistent with Galileo spectroscopy. Within the bounds of this simple model, a wide range of possible layered structures may result; the final state depends on the details of intracrustal differentiation. Devolatilization of the rocky mantle and hydrothermal brine reactions could have produced very different ocean/crust compositions, e.g., an ocean/crust of sodium carbonate or sulfuric acid, or a crust containing abundant clathrate hydrates. Realistic chemical-physical evolution scenarios differ greatly in detailed predictions, but they generally call for a highly impure and chemically layered crust. Some of these models could lead also to lateral chemical heterogeneities by diapiric upwellings and/or cryovolcanism. We describe some plausible geological consequences of the physical-chemical structures predicted from these scenarios. These predicted consequences and observed aspects of Europa's geology may serve as a basis for further analys is and discrimination among several alternative scenarios. Most chemical pathways could support viable ecosystems based on analogy with the metabolic and physiological versatility of terrestrial microorganisms. ?? 2000 Academic Press.

  15. Influence of Ply Waviness on Fatigue Life of Tapered Composite Flexbeam Laminates

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.

    1999-01-01

    Nonlinear tapered flexbeam laminates, with significant ply waviness, were cut from a full-size composite rotor hub flexbeam. The specimens were tested under combined axial tension and cyclic bending loads. All of the specimens had wavy plies through the center and near the surfaces (termed marcelled areas), although for some of the specimens the surface marcels were very obvious, and for others they were much smaller. The specimens failed by first developing cracks through the marcels at the surfaces, and then delaminations grew from those cracks, in both directions. Delamination failure occurred in these specimens at significantly shorter fatigue lives than similar specimens without waviness, tested in ref. 2. A 2D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. In addition, the FE model duplicated the waviness observed in one of the test specimens. The model was analyzed using a geometrically nonlinear FE code. Modifications were made to the original model to reduce the amplitude of the marcels near the surfaces. The analysis was repeated for each modification. Comparisons of the interlaminar normal stresses, sigma(sub n), in the various models showed that under combined axial-tension and cyclic-bending loading, for marcels of the same aspect ratio, sigma(sub n) stresses increased as the distance along the taper, from thick to thin end, increased. For marcels of the same aspect ratio and at the same X-location along the taper, sigma(sub n) stresses decreased as the distance from the surface into the flexbeam interior increased. A technique was presented for determining the smallest acceptable marcel aspect ratio at various locations in the flexbeam.

  16. Sulfide isotopic compositions in shergottites and ALH84001, and possible implications for life on Mars

    SciTech Connect

    Greenwood, J.P.; McSween, H.Y. Jr.; Riciputi, L.R.

    1997-10-01

    The shergottite and ALH84001 meteorites hold keys for understanding geologic and possibly biologic processes on Mars. Recently, it has been proposed that carbonates in ALH84001, and the Fe-sulfides they contain, are products of extraterrestrial biogenic activity. Here we report ion microprobe analyses of sulfides in shergottites and ALH84001. The sulfur isotope ratios of igneous pyrrhotites in shergottites (mean {delta}{sup 34}S{sub CDT}: Shergotty = -0.4{per_thousand}, Zagami = +2.7{per_thousand}, EETA79001A = 1.9{per_thousand}, EETA79001B = -1.7{per_thousand}, LEW88516 = -1.9{per_thousand}, QUE94201 = +0.8{per_thousand}) are similar to those of terrestrial ocean-floor basalts, suggesting that the sulfur isotopic composition of the Martian mantle may be similar to that of the mantle of the Earth. The sulfur isotopic systematics of ALH84001 sulfides are distinct from the shergottites. Measured sulfur isotope ratios of eight pyrite grains ({delta}{sup 34}S{sub CDT} = +2.0 to +7.3{per_thousand}) in crushed zones confirm previously reported analyses of isotopically heavy sulfides and are indistinguishable from an Fe-sulfide zone within a carbonate globule ({delta}{sup 34}S{sub CDT} = +6.0{per_thousand}). Analyses of synthesized, fine-grained mixtures of sulfide, carbonate, and magnetite indicate than the measured sulfur isotope ratio is independent of the presence of carbonate and magnetite in the sputtered volume, confirming the accuracy of the analysis of the fine-grained sulfide in the carbonate globule. Terrestrial biogenic sulfate reduction typically results in light isotopic enrichments. The similarity of {delta}{sup 34}S values of the sulfides in ALH84001 imply that the Fe-sulfide zones within ALH84001 carbonates are probably not the result of bacterial reduction of sulfate. 38 refs., 3 figs., 1 tab.

  17. Subcellular distribution and life cycle of Epstein-Barr virus in keratinocytes of oral hairy leukoplakia.

    PubMed Central

    Rabanus, J. P.; Greenspan, D.; Petersen, V.; Leser, U.; Wolf, H.; Greenspan, J. S.

    1991-01-01

    The authors investigated the life cycle of Epstein-Barr virus (EBV) in keratinocytes of oral hairy leukoplakia by combining immunohistochemistry. DNA in situ hybridization, and lectin histochemistry with electron microscopy. Diffuse-staining components of the EBV early antigen complex (EA-D), EBV 150-kd capsid antigen (VCA), EBV membrane antigen (gp350/220), and double-stranded DNA were labeled with monoclonal antibodies. An EBV-DNA probe was used to locate EBV DNA. Wheat-germ agglutinin (WGA) was employed to distinguish Golgi-associated compartments. The authors found EBV proteins and EBV DNA only in keratinocytes with apparent viral assembly. In situ hybridization showed EBV DNA in free corelike material and in electron-dense cores of mature nucleocapsids. Monoclonal antibodies to nonspecific double-stranded DNA attached to the same structures and to marginated chromatin. Components of EA-D were dispersed throughout the nuclei but accumulated near condensed chromatin and in 'punched-out' regions of the chromatin. Epstein-Barr virus 150-kd capsid antigen was found only in the nuclei, where it appeared preferentially on mature nucleocapsids. As yet unexplained arrays of intranuclear particles that remained unlabeled with all EBV-specific probes reacted intensely with an antiserum against common papillomavirus antigen. Gp350/220 was detectable in various cellular membrane compartments and was highly concentrated on EBV envelopes in peripheral Golgi-associated secretory vesicles. It was less abundant on the extracellular EBV, indicating that viral membrane antigen partly dissociates from the mature virus. Combined lectin-binding histochemistry and electron microscopy demonstrated for the first time that EBV is processed in the Golgi apparatus, which eventually releases the virus by fusion with the plasma membrane. These results provide insight into the biologic events that occur during complete EBV replication in vivo. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 PMID:1649554

  18. S3QL: A distributed domain specific language for controlled semantic integration of life sciences data

    PubMed Central

    2011-01-01

    Background The value and usefulness of data increases when it is explicitly interlinked with related data. This is the core principle of Linked Data. For life sciences researchers, harnessing the power of Linked Data to improve biological discovery is still challenged by a need to keep pace with rapidly evolving domains and requirements for collaboration and control as well as with the reference semantic web ontologies and standards. Knowledge organization systems (KOSs) can provide an abstraction for publishing biological discoveries as Linked Data without complicating transactions with contextual minutia such as provenance and access control. We have previously described the Simple Sloppy Semantic Database (S3DB) as an efficient model for creating knowledge organization systems using Linked Data best practices with explicit distinction between domain and instantiation and support for a permission control mechanism that automatically migrates between the two. In this report we present a domain specific language, the S3DB query language (S3QL), to operate on its underlying core model and facilitate management of Linked Data. Results Reflecting the data driven nature of our approach, S3QL has been implemented as an application programming interface for S3DB systems hosting biomedical data, and its syntax was subsequently generalized beyond the S3DB core model. This achievement is illustrated with the assembly of an S3QL query to manage entities from the Simple Knowledge Organization System. The illustrative use cases include gastrointestinal clinical trials, genomic characterization of cancer by The Cancer Genome Atlas (TCGA) and molecular epidemiology of infectious diseases. Conclusions S3QL was found to provide a convenient mechanism to represent context for interoperation between public and private datasets hosted at biomedical research institutions and linked data formalisms. PMID:21756325

  19. Life span and tissue distribution of 111indium-labeled blood platelets in hypomagnesemic lambs

    SciTech Connect

    Schneider, M.D.; Miller, J.K.; White, P.K.; Ramsey, N.

    1983-05-01

    Circulating platelets may be activated by exposed triple-helical collagen in atherosclerotic lesions in Mg-deficient ruminants. Autologous platelets, labeled in vitro with 111In and determined to be active, were injected into 5 hypomagnesemic and 3 control lambs fed semipurified diets with 100 or 2,000 mg of Mg/kg of feed for 3 months. During the first 68 hours, 111In concentrations were 11 times higher in packed cells than in plasma. Packed-cell 111In increased 60% during the first 2 hours, probably due to initial tissue sequestration and later release of labeled platelets. Thereafter, platelet half-life span averaged 60 and 63 hours for hypomagnesemic and control lambs. After 68 hours, lambs were injected with native vascular collagen fibrils at 500 micrograms/kg of body weight to initiate reversible platelet aggregation. Within 1 minute, 83% of packed-cell 111In disappeared from circulation. Thirty minutes later, the lambs were euthanatized and necropsied and in the lungs, liver, and spleen, 111In averaged 24%, 19%, and 9%, respectively, of 111In injected 68 hours earlier. Organ deposits were not affected by Mg intake, but 111In in the lungs was somewhat lower in 2 lambs injected with inactivated collagen. Pathologic changes induced by reversible platelet aggregation were compatible with right ventricular failure complicated by pulmonary edema, similar to changes in hypomagnesemic lambs that died spontaneously. Platelets in blood exposed to vascular lesions in hypomagnesemic ruminants could be a major mortality risk factor in grass tetany disease.

  20. The Role of Distribution Infrastructure and Equipment in the Life-cycle Air Emissions of Liquid Transportation Fuels

    NASA Astrophysics Data System (ADS)

    Strogen, Bret Michael

    Production of fuel ethanol in the United States has increased ten-fold since 1993, largely as a result of government programs motivated by goals to improve domestic energy security, economic development, and environmental impacts. Over the next decade, the growth of and eventually the total production of second generation cellulosic biofuels is projected to exceed first generation (e.g., corn-based) biofuels, which will require continued expansion of infrastructure for producing and distributing ethanol and perhaps other biofuels. In addition to identifying potential differences in tailpipe emissions from vehicles operating with ethanol-blended or ethanol-free gasoline, environmental comparison of ethanol to petroleum fuels requires a comprehensive accounting of life-cycle environmental effects. Hundreds of published studies evaluate the life-cycle emissions from biofuels and petroleum, but the operation and maintenance of storage, handling, and distribution infrastructure and equipment for fuels and fuel feedstocks had not been adequately addressed. Little attention has been paid to estimating and minimizing emissions from these complex systems, presumably because they are believed to contribute a small fraction of total emissions for petroleum and first generation biofuels. This research aims to quantify the environmental impacts associated with the major components of fuel distribution infrastructure, and the impacts that will be introduced by expanding the parallel infrastructure needed to accommodate more biofuels in our existing systems. First, the components used in handling, storing, and transporting feedstocks and fuels are physically characterized by typical operating throughput, utilization, and lifespan. US-specific life-cycle GHG emission and water withdrawal factors are developed for each major distribution chain activity by applying a hybrid life-cycle assessment methodology to the manufacturing, construction, maintenance and operation of each component. In order to apply the new emission factors to policy-relevant scenarios, a projection is made for the fleet inventory of infrastructure components necessary to distribute 21 billion gallons of ethanol (the 2022 federal mandate for advanced biofuels under the Energy Independence and Security Act of 2007) derived entirely from Miscanthus grass, for comparison to the baseline petroleum system. Due to geographic, physical and chemical properties of biomass and alcohols, the distribution system for Miscanthus-based ethanol is more capital- and energy-intensive than petroleum per unit of fuel energy delivered. The transportation of biofuels away from producer regions poses environmental, health, and economic trade-offs that are herein evaluated using a simplified national distribution network model. In just the last ten years, ethanol transportation within the contiguous United States is estimated to have increased more than ten-fold in total t-km as ethanol has increasingly been transported away from Midwest producers due to air quality regulations pertaining to gasoline, renewable fuel mandates, and the 10% blending limit (i.e., the E10 blend wall). From 2004 to 2009, approximately 10 billion t-km of ethanol transportation are estimated to have taken place annually for reasons other than the E10 blend wall, leading to annual freight costs greater than $240 million and more than 300,000 tonnes of CO2-e emissions and significant emissions of criteria air pollutants from the combustion of more than 90 million liters of diesel. Although emissions from distribution activities are small when normalized to each unit of fuel, they are large in scale. Archetypal fuel distribution routes by rail and by truck are created to evaluate the significance of mode choice and route location on the severity of public health impacts from locomotive and truck emissions, by calculating the average PM2.5 pollution intake fraction along each route. Exposure to pollution resulting from trucking is found to be approximately twice as harmful as rail (while trucking is five times more energy intensive). Transporting fuel from the Midwest to California would result in slightly lower human health impacts than transportation to New Jersey, even though California is more than 50% farther from the Midwest than most coastal Northeast states. In summary, this dissertation integrated concepts from infrastructure management, climate and renewable fuel policy, fuel chemistry and combustion science, air pollution modeling, public health impact assessment, network optimization and geospatial analysis. In identifying and quantifying opportunities to minimize damage to the global climate and regional air quality from fuel distribution, results in this dissertation provide credence to the urgency of harmonizing policies and programs that address national and global energy and environmental goals. Under optimal future policy and economic conditions, infrastructure will be highly utilized and transportation minimized in order to reduce total economic, health, and environmental burdens associated with the entire supply and distribution chain for transportation fuels. (Abstract shortened by UMI.)

  1. Within-twig leaf distribution patterns differ among plant life-forms in a subtropical Chinese forest.

    PubMed

    Meng, Fengqun; Cao, Rui; Yang, Dongmei; Niklas, Karl J; Sun, Shucun

    2013-07-01

    In theory, plants can alter the distribution of leaves along the lengths of their twigs (i.e., within-twig leaf distribution patterns) to optimize light interception in the context of the architectures of their leaves, branches and canopies. We hypothesized that (i) among canopy tree species sharing similar light environments, deciduous trees will have more evenly spaced within-twig leaf distribution patterns compared with evergreen trees (because deciduous species tend to higher metabolic demands than evergreen species and hence require more light), and that (ii) shade-adapted evergreen species will have more evenly spaced patterns compared with sun-adapted evergreen ones (because shade-adapted species are generally light-limited). We tested these hypotheses by measuring morphological traits (i.e., internode length, leaf area, lamina mass per area, LMA; and leaf and twig inclination angles to the horizontal) and physiological traits (i.e., light-saturated net photosynthetic rates, Amax; light saturation points, LSP; and light compensation points, LCP), and calculated the 'evenness' of within-twig leaf distribution patterns as the coefficient of variation (CV; the higher the CV, the less evenly spaced leaves) of within-twig internode length for 9 deciduous canopy tree species, 15 evergreen canopy tree species, 8 shade-adapted evergreen shrub species and 12 sun-adapted evergreen shrub species in a subtropical broad-leaved rainforest in eastern China. Coefficient of variation was positively correlated with large LMA and large leaf and twig inclination angles, which collectively specify a typical trait combination adaptive to low light interception, as indicated by both ordinary regression and phylogenetic generalized least squares analyses. These relationships were also valid within the evergreen tree species group (which had the largest sample size). Consistent with our hypothesis, in the canopy layer, deciduous species (which were characterized by high LCP, LSP and Amax) had more even leaf distribution patterns than evergreen species (which had low LCP, LSP and Amax); shade-adapted evergreen species had more even leaf distribution patterns than sun-adapted evergreen species. We propose that the leaf distribution pattern (i.e., 'evenness' CV, which is an easily measured functional trait) can be used to distinguish among life-forms in communities similar to the one examined in this study. PMID:23933830

  2. Computed-tomography scan-based finite element analysis of stress distribution in premolars restored with composite resin

    NASA Astrophysics Data System (ADS)

    Kantardžić, I.; Vasiljević, D.; Blažić, L.; Puškar, T.; Tasić, M.

    2012-05-01

    Mechanical properties of restorative material have an effect on stress distribution in the tooth structure and the restorative material during mastication. The aim of this study was to investigate the influence of restorative materials with different moduli of elasticity on stress distribution in the three-dimensional (3D) solid tooth model. Computed tomography scan data of human maxillary second premolars were used for 3D solid model generation. Four composite resins with a modulus of elasticity of 6700, 9500, 14 100 and 21 000 MPa were considered to simulate four different clinical direct restoration types. Each model was subjected to a resulting force of 200 N directed to the occlusal surface, and stress distribution and maximal von Mises stresses were calculated using finite-element analysis. We found that the von Mises stress values and stress distribution in tooth structures did not vary considerably with changing the modulus of elasticity of restorative material.

  3. Life history and vertical distribution of the mesopelagic fish Cyclothone alba (family Gonostomatidae) in Sagami Bay, Central Japan

    NASA Astrophysics Data System (ADS)

    Miya, Masaki; Nemoto, Takahisa

    1986-08-01

    Life history and vertical distribution of the mesopelagic fish Cyclothone alba (family Gonostomatidae) are described on the basis of over 4000 specimens taken during a series of 15 cruises from December 1982 to December 1984 at a station near the center of Sagami Bay, Central Japan. C. alba does not undertake diel vertical migrations, being concentrated in the mesopelagic zone between 300 and 500 m, with peak abundance at 350 m both day and night. Spawning occurs mainly during the late spring and summer months in Sagami Bay. C. alba is semelparous, releasing about 200-650 eggs at the end of its life. Duration of the egg and larval stages is estimated to be about 2-3 months. Many males and some females mature at 1 year, and all individuals mature by 2 years of age. Sexual dimorphism in smaller males and larger females results from an earlier decline of growth rate in males: on the average, males reach 17.5 mm SL (standard length) in 1 year and 21 mm SL in 2 years, whereas females reach 19 mm SL in 1 year and 26 mm SL in 2 years. It is suggested that such precocious maturation, together with its small larvalized form, is attained through progenesis.

  4. Life cycle analysis of distributed concentrating solar combined heat and power: economics, global warming potential and water

    NASA Astrophysics Data System (ADS)

    Norwood, Zack; Kammen, Daniel

    2012-12-01

    We report on life cycle assessment (LCA) of the economics, global warming potential and water (both for desalination and water use in operation) for a distributed concentrating solar combined heat and power (DCS-CHP) system. Detailed simulation of system performance across 1020 sites in the US combined with a sensible cost allocation scheme informs this LCA. We forecast a levelized cost of 0.25 kWh-1 electricity and 0.03 kWh-1 thermal, for a system with a life cycle global warming potential of ˜80 gCO2eq kWh-1 of electricity and ˜10 gCO2eq kWh-1 thermal, sited in Oakland, California. On the basis of the economics shown for air cooling, and the fact that any combined heat and power system reduces the need for cooling while at the same time boosting the overall solar efficiency of the system, DCS-CHP compares favorably to other electric power generation systems in terms of minimization of water use in the maintenance and operation of the plant. The outlook for water desalination coupled with distributed concentrating solar combined heat and power is less favorable. At a projected cost of 1.40 m-3, water desalination with DCS-CHP would be economical and practical only in areas where water is very scarce or moderately expensive, primarily available through the informal sector, and where contaminated or salt water is easily available as feed-water. It is also interesting to note that 0.40-1.90 m-3 is the range of water prices in the developed world, so DCS-CHP desalination systems could also be an economical solution there under some conditions.

  5. Microbial Biomass Distribution and Compositional Changes Associated with a Warmer Climate in Boreal Forest Soils

    NASA Astrophysics Data System (ADS)

    Kohl, L.; Jérôme, J.; Billings, S. A.; Edwards, K.; Morrill, P. L.; Ziegler, S. E.

    2013-12-01

    Predicting the physiological and structural changes of the microbial community in warming soils is essential for a functional understanding of climate feedback mechanisms. Laboratory and field experiments have often found that warming increases soil organic carbon (SOC) mineralization and decreases microbial biomass, but remain more inconclusive regarding microbial community structure. These experiments, however, have been limited to responses on a time scale of months to years, while soil properties change over decades to centuries. Studies along climate gradients may prove helpful in elucidating how climate history affects soil properties, including microbial community structure. We present the phospholipid fatty acid (PLFA) based community characterization of the organic (L, F, H) and mineral (B; top 10cm) horizons of podzols from two mesic boreal forest sites similar in most aspects (e.g. stand type, class and age) but differing in mean annual temperature (MAT) by almost 6°C. This temperature difference is similar to the warming predicted for this region by 2100. Results are compared to respiration rates in laboratory incubations. We observed consistent PLFA derived biomass per unit SOC throughout the profile, independent of depth or site. The organic horizons contained similar amounts of SOC and PLFA as the top 10 cm of the mineral horizon (2.5-3.4 kg C m-2; 10.3-12.6 mmol PLFA m-2). Within the organic horizon, the greatest proportion of SOC and PLFA were found in the F horizon. The overall distribution of PLFA among the soil horizons was largely unaffected by climate regime, except that biomass was shifted from F to L horizons at the warmer site (from 12% to 29% of total organic horizon PLFA located in L) indicating that biomass was located closer to the surface in warmer sites. A similar shift was found in respiration (26 vs. 42% of organic horizon CO2 from L). As expected, community structure changed with depth. The abundance of fungal and protozoan PLFA decreased and that of Gram+ and Gram- bacteria increased in deeper soil horizons. Within each horizon, community composition was well constrained and did not vary with climate except for higher contributions of long chain (C20+) saturated fatty acids at the colder site. Interestingly, the ratio cy17:0/16:1ω7, a physiological indicator of elevated stress or dormancy for the bacterial communities, was elevated within the warmer sites and mineral horizons. This is congruent with SOC normalized respiration rates that were least 5x lower in B relative to the LFH horizons and 50% lower within F and H horizons from the warmer relative colder site. In combination these results suggest that the microbial community in deeper soil horizons and from the warmer climate regime contain a microbial community equally abundant relative to the soil C pool sizes, but not as prolific in CO2 production. Overall, our results suggest that relatively warm climatic regimes in the boreal zone can promote shallower peaks of soil microbial biomass and respiration and shifts in physiology compared to cooler systems, but no discernible differences in community composition.

  6. Alkenone distribution in Lake Van sediment over the last 270 ka: influence of temperature and haptophyte species composition

    NASA Astrophysics Data System (ADS)

    Randlett, Marie-Ève; Coolen, Marco J. L.; Stockhecke, Mona; Pickarski, Nadine; Litt, Thomas; Balkema, Cherel; Kwiecien, Ola; Tomonaga, Yama; Wehrli, Bernhard; Schubert, Carsten J.

    2014-11-01

    Fossil long-chain alkenones have been used for several decades to reconstruct past ocean surface water temperatures and gained recent interest as a paleotemperature proxy for continental lake settings. However, factors besides temperature can affect alkenone distributions in haptophyte algae, and alkenone compositions can differ between haptophyte species. Alkenone-biosynthesizing haptophyte algae are genetically much more diverse in lakes than in the marine realm, and species-level variations in alkenone compositions could have implications for alkenone paleothermometry. Here, we performed a paired analysis of alkenone distributions and haptophyte species compositions using ancient DNA in up to 270 ka-old sediments of Lake Van in Turkey to reveal a possible species-effect on fossil alkenone distributions and paleotemperature estimates. The same predominant haptophyte in Lake Van today prevailed also since the last ˜100 ka. However, a calibration of alkenone paleotemperature especially in the oldest analyzed intervals is complicated due to a more complex haptophyte species composition predominated by a haptophyte (LVHap_6), which is phylogenetically different from sequences recovered from currently existing lakes including Lake Van and from haptophyte species existing in culture. The predominance of LVHap_6 coincided with the presence of alkenone MeC38:3 and relatively high MeC37:3/4 (2.4) and MeC38:4/5 ratios (3.0). Uk37 index values in the sediment core over the last 270 ka reflect relative changes in past temperature and are additionally linked to haptophyte species composition. A sustained period of high salinity, as indicated by pore-water salinity measurements, could potentially have triggered the succession of haptophytes as sources of alkenones in Lake Van.

  7. Distribution of leucocyte populations, and milk composition, in milk fractions of healthy quarters in dairy cows.

    PubMed

    Sarikaya, Hande; Werner-Misof, Claudia; Atzkern, Melanie; Bruckmaier, Rupert M

    2005-11-01

    The goal of the study was to evaluate the composition of leucocyte populations in different milk fractions as a basis on which to judge their possible role in the immune response in different compartments of the udder. The milk of one healthy quarter of nine dairy cows (SCC/quarter distribution of leucocyte populations and their viability. The content of fat increased steadily during milking and reached highest values in R. Protein and lactose increased from C to A25, decreased from A25 to A100 and reached their minimum in R. Na and Cl ion levels diminished from C to A25 and thereafter increased from A50 to R. Electrical Conductivity (EC) also decreased from C to A25 but remained similar within the alveolar samples and reached a minimum in R. SCC decreased from C to a minimum in A25 and increased subsequently to a significant maximum in R. Somatic cell viability increased throughout consecutive fractions with a maximum value in R. The ratio of cell populations in the various milk fractions showed a reverse trend of macrophages (M) and polymorphonuclear neutrophils (PMN). M values were highest in C while PMN levels increased to their maximum in the R fraction. The lymphocyte (L) fraction remained similar in C, A25, A50, A75 and R but was higher in A100. Proportions of L, PMN and M were, respectively, 9.3%, 38.2%, 52.3% in C, 10.9%, 64%, 25.1% in A25-A100 and 10.2%, 64.9%, 24.8% in R. Numbers of L, PMN and M in milk showed a similar pattern for all three cell types: high levels in C decreased to a minimum at A25 and increased steadily thereafter to their maxima in R. It is concluded that, for healthy quarters, M, the predominant cell type in C, are located near the teat canal, the main entrance of pathogens. Obviously they are the first immunological barriers for invading pathogens. In contrast, PMN are the most important population in the alveolar compartment. However, each leucocyte fraction had a higher concentration in C than in early alveolar fractions, thus indicating the crucial role of immune defence in the cisternal compartment. PMID:16223466

  8. Analysis of the distribution of the isotopic composition of evapotranspiration flux in a semi-arid savanna.

    NASA Astrophysics Data System (ADS)

    Good, Stephen; O'Connor, Molly; Soderberg, Keir; Wang, Lixin; Caylor, Kelly

    2013-04-01

    The cycling of water in semi-arid regions is critical for the ecohydrologic processes of savanna systems. Stable isotopes of water serve as important tracers of water movement, and studies of how the isotopic distribution of rainfall is transformed through geomorphic basin characteristics into an isotopic distribution of runoff have yielded insight into watershed dynamics. However, in many drylands, the majority of return flux of water out of ecosystems is in the form of evapotranspiration. Through a combination of field measurements and modeling, we present a study of the factors that influence the transformation of the isotopic distribution of precipitation into an isotopic distribution of evapotranspiration. Field observations were collected at a micrometerological tower located in a mixed-savanna in Laikipa, Kenya. The tower is equipped with an off-axis integrated cavity output spectroscopy system (ICOS), and the isotopic composition of atmospheric water vapor has been sampled at 1 Hz from 2010 through 2012. Evapotranspiration isotopic composition is estimated based on Keeling plots for each 30 minute time period, with seasonal dynamics evident throughout this multi-year study. Isotopic analysis of collected rainfall and cryogenic vacuum distillation of soil and plant samples at the site aid in the interpretation of water cycling. A decrease in the variance of evapotranspiration flux composition relative to precipitation is indicative of soil water mixing as well as runoff and recharge effects. Stochastic modeling of the isotopic inputs and outputs of the semi-arid systems demonstrates the strength of the influence that rainfall climatology, plant rooting depth, and evapotranspiration characteristics have on the ratio of the variances of input and output isotopic composition.

  9. Formation, composition and particle size distribution of fly-ashes from biomass combustion plants

    SciTech Connect

    Brunner, T.; Dahl, J.; Obernberger, I.

    1998-12-31

    Due to the fact that fly-ash particles and aerosols formed during biomass combustion and gasification processes are contaminated with environmentally harmful heavy metals like zinc, cadmium and lead, efficient dust removal from the flue gas is of great importance. In order to characterize biomass fly-ashes and to describe and investigate influencing factors on fly-ash and dust formation, comprehensive particle size measurements were performed with low pressure Berner-type cascade impactors under consideration of different combustion technologies and various types of biomass fuels (bark, wood chips and straw). The results showed that biomass fly-ash can be divided into two major fractions differing in particle size and composition. The first fraction consists of coarse fly-ash particles with an average particle size larger than 5{micro}m results from particles entrained from the fuel bed and is formed mainly by non-volatile minerals (Si, Ca, Mg). The second fraction consists of aerosols (particles smaller than 1{micro}m) which are formed when the flue gas is cooled (in the heat exchanger section) by condensation of volatile ash forming compounds. Chemical analyses of aerosol particles collected by low-pressure impactors revealed that these particles mainly consist of chlorides and sulfates of alkali compounds. These results are in accordance with the outputs of chemical equilibrium calculations performed for the test run conditions. Concerning heavy metal concentrations, the aerosols formed in grate furnaces contain considerable amounts of the environmentally relevant and volatile heavy metals Cd, Zn and Pb due to condensation of metal vapors with decreasing flue gas temperature. The aerosols formed in CFB combustion plants do not contain significant amounts of heavy metals which means that in these systems condensation of gaseous metal compounds does not play a major role. Chemical surface reactions between coarse fly-ash particles and metal vapors seem to be dominant. The particle size distribution of aerosols formed in grate combustion systems is unimodal and has a distinct peak in the range < 1{micro}m without major variations between different biomass fuels. For bark, wood chips and sawdust the major amount of aerosols appears in the range of approximately 0.1{micro}m (Stokes diameter). The dominating particle size of aerosols formed during straw combustion is about 0.5{micro}m. Concerning the combustion of wood and bark, no significant influence of the fuel particle size, the combustion temperature and the boiler load on the size distribution of aerosols was detected for wood and bark in grate furnaces. However, the total amount of aerosols formed by different biomass fuels differs considerably and can be explained by the varying amounts of volatile alkali metals (mainly K and Na), sulfur and chloride in the fuels. That is, the combustion of straw displays total aerosol amounts of up to 900 mg/Nm{sup 3} (related to dry flue gas and 13 Vol.% O{sub 2}) which is about 10 times higher than the emissions of bark- and hardwood-fired grate combustion units. A second influencing parameter revealed is the temperature of combustion. Raising combustion temperatures increase the total amount of aerosols formed.

  10. Derangement of composite filler distribution inside syringe-type delivery systems.

    PubMed

    Braem, M J; Lambrechts, G; Davidson, C L; Vansant, E F; Vanhoof, C

    1993-01-01

    Used and almost emptied syringes of two brands of composites contained material close to the pestle-head that appeared to be more granular and dry, as compared to the composite obtained from unused syringes. The present results suggest that a derangement of filler and matrix phases occurred inside the used syringes when compared to unused controls. Stress imposed on the composite material inside the unused syringes resulted in a comparable derangement of filler and matrix phases. Although this derangement was limited, the effect could contribute to intra- and interlaboratory scattering of data. PMID:8299865

  11. Source apportionment of ambient fine particle from combined size distribution and chemical composition data during summertime in Beijing

    NASA Astrophysics Data System (ADS)

    Liu, Z. R.; Wang, Y. S.; Liu, Q.; Hu, B.; Sun, Y.

    2013-01-01

    Continuous particle number concentration and chemical composition data were collected over one month during summertime in Beijing to investigate the source apportionment of ambient fine particles. Particle size distributions from 15 nm to 2.5 μm in diameter and composition data, such as organic matter, sulfate, nitrate, ammonium, chlorine, and gaseous pollutants, were analyzed using positive matrix factorisation (PMF) which indentified eight factors: cooking, solid mode exhaust, nucleation mode exhaust, accumulation mode, secondary nitrate, secondary sulfate, coal-fired power plant and road dust. Nearly two-thirds of particle number concentrations were attributed to cooking (22.8%) and motor vehicle (37.5%), whereas road dust, coal-fired power plant and regional sources contributed 69.0% to particle volume concentrations. Local and remote sources were distinguished using size distributions associated with each factor. Local sources were generally characterised by unimodal or bimodal number distributions, consisting mostly of particles less 0.1 μm in diameter, and regional sources were defined by mostly accumulation mode particles. Nearly one third of secondary nitrate and secondary sulfate was transported from the surrounding areas of Beijing during study period. Overall the introduction of combination of particle number concentration and chemical composition in PMF model is successful at separating the components and quantifying relative contributions to the particle number and volume population in a complex urban atmosphere.

  12. Redox centers evolution in phospho-olivine type (LiFe0.5Mn0.5 PO4) nanoplatelets with uniform cation distribution.

    PubMed

    Paolella, Andrea; Bertoni, Giovanni; Dilena, Enrico; Marras, Sergio; Ansaldo, Alberto; Manna, Liberato; George, Chandramohan

    2014-03-12

    In phospho-olivine type structures with mixed cations (LiM1M2PO4), the octahedral M1 and M2 sites that dictate the degree of intersites order/disorder play a key role in determining their electrochemical redox potentials. In the case of LiFexMn1-xPO4, for example, in micrometer-sized particles synthesized via hydrothermal route, two separate redox centers corresponding to Fe(2+)/Fe(3+) (3.5 V vs Li/Li(+)) and Mn(2+)/Mn(3+) (4.1 V vs Li/Li(+)), due to the collective Mn-O-Fe interactions in the olivine lattice, are commonly observed in the electrochemical measurements. These two redox processes are directly reflected as two distinct peak potentials in cyclic voltammetry (CV) and equivalently as two voltage plateaus in their standard charge/discharge characteristics (in Li ion batteries). On the contrary, we observed a single broad peak in CV from LiFe0.5Mn0.5PO4 platelet-shaped (∼10 nm thick) nanocrystals that we are reporting in this work. Structural and compositional analysis showed that in these nanoplatelets the cations (Fe, Mn) are rather homogeneously distributed in the lattice, which is apparently the reason for a synergetic effect on the redox potentials, in contrast to LiFe0.5Mn0.5PO4 samples obtained via hydrothermal routes. After a typical carbon-coating process in a reducing atmosphere (Ar/H2), these LiFe0.5Mn0.5PO4 nanoplatelets undergo a rearrangement of their cations into Mn-rich and Fe-rich domains. Only after such cation rearrangement (via segregation) in the nanocrystals, the redox processes evolved at two distinct potentials, corresponding to the standard Fe(2+)/Fe(3+) and Mn(2+)/Mn(3+) redox centers. Our experimental findings provide new insight into mixed-cation olivine structures in which the degree of cations mixing in the olivine lattice directly influences the redox potentials, which in turn determine their charge/discharge characteristics. PMID:24564785

  13. Development of Atmospheric Neutral Analyzer for Neutral Mass Composition and Velocity Distribution Measurements in the Upper Atmosphere

    NASA Astrophysics Data System (ADS)

    Shimoyama, M.; Hayashi, A.; Ishiguro, K.; Hirahara, M.; Yau, A. W.

    2012-12-01

    In order to understand the temporal and spatial variability of the ionosphere-thermosphere system, simultaneous measurements of the composition and density of the neutral atmosphere and the velocity distribution of individual species are essential. However, most conventional types of instruments for neutral atmosphere lack the simultaneous capability of measuring neutral atmospheric velocity and resolving neutral mass. We are designing the Atmospheric Neutral Analyzer (ANA) instrument to measure neutral composition and velocity distribution simultaneously in the thermosphere. It is designed to measure the detailed, mass-resolved 2-dimensional velocity distribution of neutral species, and to derive the corresponding density, mass composition, bulk velocity and temperature from the measured distribution. The ANA is comprised of 4 sections; Entrance Aperture (EA), Ion Accelerator (IA), Radio-Frequency Ion Mass Analyzer (MA) and Imaging Particle Detector (PD). The EA consists of a planar aperture slit and deflection electrode, and functions as an incident-particle selector and collimator. A small fraction of the neutral particles is ionized by electron beam. The IA acts as a particle energy selector by accelerating the ionized neutral particles. The MA acts as an ion velocity selector. The radio-frequency voltage is applied to grids and selectively accelerates ions of matching speed. As a result, ions with a particular mass-per-charge are selected. The PD, which is comprised of a retarding grid, micro-channel plate and charge coupled device, detects the mass-selected ions, and a 2-dimensional image of velocity distribution is obtained. We present the detailed design of the ANA in this paper.

  14. Fatigue Life Prediction of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures. Part I: Experimental Analysis

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-04-01

    This paper presents an experimental analysis on the fatigue behavior in C/SiC ceramic-matrix composites (CMCs) with different fiber preforms, i.e., unidirectional, cross-ply and 2.5D woven, at room and elevated temperatures in air atmosphere. The experimental fatigue life S - N curves of C/SiC composites corresponding to different stress levels and test conditions have been obtained. The damage evolution processes under fatigue loading have been analyzed using fatigue hysteresis modulus and fatigue hysteresis loss energy. By comparing the experimental fatigue hysteresis loss energy with theoretical computational values, the interface shear stress corresponding to different peak stress, fiber preforms and test conditions have been estimated. It was found that the degradation of interface shear stress and fibres strength caused by oxidation markedly decreases the fatigue life of C/SiC composites at elevated temperature.

  15. Fatigue Life Prediction of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures. Part I: Experimental Analysis

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-05-01

    This paper presents an experimental analysis on the fatigue behavior in C/SiC ceramic-matrix composites (CMCs) with different fiber preforms, i.e., unidirectional, cross-ply and 2.5D woven, at room and elevated temperatures in air atmosphere. The experimental fatigue life S - N curves of C/SiC composites corresponding to different stress levels and test conditions have been obtained. The damage evolution processes under fatigue loading have been analyzed using fatigue hysteresis modulus and fatigue hysteresis loss energy. By comparing the experimental fatigue hysteresis loss energy with theoretical computational values, the interface shear stress corresponding to different peak stress, fiber preforms and test conditions have been estimated. It was found that the degradation of interface shear stress and fibres strength caused by oxidation markedly decreases the fatigue life of C/SiC composites at elevated temperature.

  16. Evaluation of two fiber optic-based solar collection and distribution systems for advanced space life support

    NASA Technical Reports Server (NTRS)

    Jack, D. A.; Nakamura, T.; Sadler, P.; Cuello, J. L.

    2002-01-01

    Growing plants in an enclosed controlled environment is crucial in developing bioregenerative life-support systems (BLSS) for space applications. The major challenge currently facing a BLSS is the extensive use of highly energy-intensive electric light sources, which leads to substantial energy wastes through heat dissipations by these lamps. An alternative lighting strategy is the use of a solar irradiance collection, transmission, and distribution system (SICTDS). Two types of fiber optic-based SICTDS, a Fresnel-lens Himawari and a parabolic-mirror optical waveguide (OW) lighting system, were evaluated. The overall efficiency for the OW SICTDS of 40.5% exceeded by 75% that for the Himawari of 23.2%. The spectral distributions of the light delivered by the Himawari and the OW SICTDS were almost identical and had practically no difference from that of terrestrial solar radiation. The ratios of photosynthetically active radiation (PAR) to total emitted radiation (k) of 0.39 +/- 0.02 for the Himawari and 0.41 +/- 0.04 for the OW SICTDS were statistically indistinguishable, were not significantly different from that of 0.042 +/- 0.01 for terrestrial solar radiation, and were comparable to that of 0.35 for a high-pressure sodium (HPS) lamp. The coefficients of variation (CV) of 0.34 and 0.39 for PPF distributions, both at 50 mm X 50 mm square grid arrays, corresponding to the Himawari and the OW SICTDS, respectively, were comparable with each other but were both significantly greater than the CV of 0.08 corresponding to the HPS lamp. The average fresh weight or dry weight of lettuce grown in the solar chamber with either the Himawari or the OW SICTDS showed no statistical difference from the average fresh weight or dry weight of lettuce grown in the reference chamber with the HPS lamp. The results of this study suggest that an SICTDS could help reduce the electric power demand in a BLSS.

  17. Entire Life Time Monitoring of Filament Wound Composite Cylinders Using Bragg Grating Sensors: III. In-Service External Pressure Loading

    NASA Astrophysics Data System (ADS)

    Hernández-Moreno, H.; Collombet, F.; Douchin, B.; Choqueuse, D.; Davies, P.

    2009-06-01

    This article is the third of three papers describing a study of the monitoring of filament wound composite cylinders for underwater applications. Part I described the technological issues and the development of specimens instrumented with embedded gratings and thermocouples, with the aim of monitoring the temperature and strain changes during the cylinder manufacturing presented in Part II. Residual strains are not negligible, over 1,000 axial micro-strain at the end of the curing cycle. Part III describes the response of these cylinders to hydrostatic pressure loading. The same embedded fiber optical Bragg gratings (FBGs) used for parts I and II of the study are here used as strain gauges. Their response is compared to that of classical resistive strain gages bonded to the inner surface of the tube. Results from these initial tests demonstrate the embedded FBG sensor’s capability to monitor structural health of an underwater structure from fabrication throughout its service life. Embedded instrumentation records strains during pressure cycles up to final failure, without affecting the cylinder response.

  18. Decapod crustacean larval communities in the Balearic Sea (western Mediterranean): Seasonal composition, horizontal and vertical distribution patterns

    NASA Astrophysics Data System (ADS)

    Torres, Asvin P.; Dos Santos, Antonina; Balbín, Rosa; Alemany, Francisco; Massutí, Enric; Reglero, Patricia

    2014-10-01

    Decapod crustaceans are the main target species of deep water bottom trawl fisheries in the Balearic Sea but little is known about their larval stages. This work focuses on the species composition of the decapod larval community, describing the main spatio-temporal assemblages and assessing their vertical distribution. Mesozooplankton sampling was carried out using depth-stratified sampling devices at two stations located over the shelf break and the mid slope, in the north-western and southern Mallorca in late autumn 2009 and summer 2010. Differences among decapod larvae communities, in terms of composition, adult's habitat such as pelagic or benthic, and distribution patterns were observed between seasons, areas and station. Results showed that for both seasons most species and developmental stages aggregated within the upper water column (above 75 m depth) and showed higher biodiversity in summer compared to late autumn. Most abundant species were pelagic prawns (e.g., Sergestidae) occurring in both seasons and areas. The larval assemblages' distributions were different between seasonal hydrographic scenarios and during situations of stratified and non-stratified water column. The vertical distribution patterns of different larval developmental stages in respect to the adult's habitat were analyzed in relation to environmental variables. Fluorescence had the highest explanatory power. Four clearly different vertical patterns were identified: two corresponding to late autumn, which were common for all the main larval groups and other two in summer, one corresponding to larvae of coastal benthic and the second to pelagic species larvae.

  19. Defect distribution and compositional inhomogeneities in Al0.5Ga0.5N layers grown on stepped surfaces

    NASA Astrophysics Data System (ADS)

    Mogilatenko, A.; Knauer, A.; Zeimer, U.; Weyers, M.

    2016-02-01

    This study reports on defect distribution and compositional homogeneity of Al x Ga1-x N layers with a nominal composition x of 0.5 grown on AlN by metal organic vapor phase epitaxy. The AlN layers with a low threading dislocation density (TDD) of a few 108 cm-2 were obtained by ELO and showed periodic surface macrosteps. Al x Ga1-x N growth on these AlN surfaces results in inhomogeneous Ga distribution due to enhanced Ga incorporation on the macrostep sidewalls. Variation of AlGaN deposition rate strongly influences the Ga distribution as well as the defect structure in the layers. Low growth rates (0.2 μm h-1) result in an inhomogeneous TD distribution with formation of alternating stripes with lower and higher defect densities. Additionally, self-organized formation of additional Ga-rich areas at the top edge of the steps is observed. In contrast, at a higher growth rate of 1 μm h-1 the formation of additional Ga-rich areas can be completely suppressed, but the defect density increases. This leads to an optimum growth rate to minimize the TDD.

  20. Species composition, richness, and distribution of marine bivalve molluscs in Bahía de Mazatlán, México

    PubMed Central

    Esqueda-González, María del Carmen; Ríos-Jara, Eduardo; Galván-Villa, Cristian Moises; Rodríguez-Zaragoza, Fabian Alejandro

    2014-01-01

    Abstract We describe the composition and distribution of bivalve molluscs from the sandy and rocky intertidal and the shallow subtidal environments of Bahía de Mazatlán, México. The bivalve fauna of the bay is represented by 89 living species in 28 families, including 37 new records and four range extensions: Lithophaga hastasia, Adula soleniformis, Mactrellona subalata, and Strigilla ervilia. The number of species increases from the upper (44) and lower intertidal (53) to the shallow subtidal (76), but only 11 (17%) have a wide distribution in the bay (i.e., found in all sampling sites and environments). The bivalve assemblages are composed of four main life forms: 27 epifaunal species, 26 infaunal, 16 semi-infaunal, and 20 endolithic. A taxonomic distinctness analysis identified the sampling sites and environments that contribute the most to the taxonomic diversity (species to suborder categories) of the bay. The present work increased significantly (31%) to 132 species previous inventories of bivalves of Bahía de Mazatlán. These species represent 34% of the bivalve diversity of the southern Golfo de California and approximately 15% of the Eastern Tropical Pacific region. PMID:24843252

  1. Simultaneous deconvolution of the bivariate distribution of molecular weight and chemical composition of polyolefins made with ziegler-natta catalysts.

    PubMed

    Alghyamah, Abdulaziz A; Soares, João B P

    2009-02-18

    Polyolefins made with Ziegler-Natta catalysts have non-uniform distributions of molecular weight (MWD) and chemical composition (CCD). The MWD is usually measured by high-temperature gel permeation chromatography (GPC) and the CCD by either temperature rising elution fractionation (TREF) or crystallization analysis fractionation (CRYSTAF). A mathematical model is needed to quantify the information provided by these analytical techniques and to relate it to the presence of multiple site types on Ziegler-Natta catalysts. We developed a robust computer algorithm to deconvolute the MWD and CCD of polyolefins simultaneously using Flory's most probable distribution and the cumulative CCD component of Stockmayer's distribution, which includes the soluble fraction commonly present in linear low-density polyethylene (LLDPE) resins and have applied this procedure for the first time to several industrial LLDPE resins. The deconvolution results are reproducible and consistent with theoretical expectations. PMID:21706614

  2. Pyrolysis as a way to close a CFRC life cycle: Carbon fibers recovery and their use as feedstock for a new composite production

    NASA Astrophysics Data System (ADS)

    Giorgini, Loris; Benelli, Tiziana; Mazzocchetti, Laura; Leonardi, Chiara; Zattini, Giorgio; Minak, Giangiacomo; Dolcini, Enrico; Tosi, Cristian; Montanari, Ivan

    2014-05-01

    Pyrolysis is shown to be an efficient method for recycling carbon fiber composites in the form of both uncured prepregs scraps or as cured end-of-life objects. The pyrolytic process leads to different products in three physical states of matter. The gaseous fraction, called syngas, can be used as energy feedstock in the process itself. The oil fraction can be used as fuel or chemical feedstock. The solid residue contains substantially unharmed carbon fibers that can be isolated and recovered for the production of new composite materials, thus closing the life cycle of the composite in a "cradle to cradle" approach. All the pyrolysis outputs were thoroughly analyzed and characterized in terms of composition for oil and gas fraction and surface characteristics of the fibers. In particular, it is of paramount importance to correlate the aspect and properties of the fibers obtained with different composite feedstock and operational conditions, that can be significantly different, with the reinforcing performance in the newly produced Recycled Carbon Fibers Reinforced Polymers. Present results have been obtained on a pyrolysis pilot plant that offers the possibility of treating up to 70kg of materials, thus leading to a significant amount of products to be tested in the further composites production, focused mainly on chopped carbon fiber reinforcement.

  3. Comparison of Fatigue Life Between C/SiC and SiC/SiC Ceramic-Matrix Composites at Room and Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-04-01

    In this paper, the comparison of fatigue life between C/SiC and SiC/SiC ceramic-matrix composites (CMCs) at room and elevated temperatures has been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S-N curves and fatigue limits of cross-ply, 2D and 3D C/SiC and SiC/SiC composites at room temperature, 550 °C in air, 750 °C in dry and humid condition, 800 °C in air, 1000 °C in argon and air, 1100 °C, 1300 °C and 1500 °C in vacuum, have been predicted. At room temperature, the fatigue limit of 2D C/SiC composite with ECFL of 20 % lies between 0.78 and 0.8 tensile strength; and the fatigue limit of 2D SiC/SiC composite with ECFL of 20 % lies between 0.75 and 0.85 tensile strength. The fatigue limit of 2D C/SiC composite increases to 0.83 tensile strength with ECFL increasing from 20 to 22.5 %, and the fatigue limit of 3D C/SiC composite is 0.85 tensile strength with ECFL of 37 %. The fatigue performance of 2D SiC/SiC composite is better than that of 2D C/SiC composite at elevated temperatures in oxidative environment.

  4. Statistical Continuum Theory for the Effective Conductivity of Fiber Filled Polymer Composites: Effect of Orientation Distribution and Aspect Ratio

    SciTech Connect

    Mikdam, Amed; Makradi, A.; Ahzi, Said; Garmestani, Hamid; Li, Dongsheng; Remond, Y.

    2010-03-01

    Effective conductivity of polymer composites, filled with conducting fibers such as carbon nanotubes, is studied using statistical continuum theory. The fiber orientation distribution in the matrix plays a very important role on their effective properties. To take into account their orientation, shape and distribution, two-point and three-point probability distribution functions are used. The effect of fibers orientation is illustrated by comparing the effective conductivity of microstructures with oriented and non-oriented fibers. The randomly oriented fibers result in an isotropic effective conductivity. The increased fiber orientation distribution can lead to higher anisotropy in conductivity. The effect of fiber’s aspect ratio on the effective conductivity is studied by comparing microstructures with varying degrees of fiber orientation distribution. Results show that the increase in anisotropy leads to higher conductivity in the maximum fiber orientation distribution direction and lower conductivity in the transverse direction. These results are in agreement with various models from the literature that show the increase of the aspect ratio of fibers improves the electrical and thermal conductivity.

  5. Creating Composite Age Groups to Smooth Percentile Rank Distributions of Small Samples

    ERIC Educational Resources Information Center

    Lopez, Francesca; Olson, Amy; Bansal, Naveen

    2011-01-01

    Individually administered tests are often normed on small samples, a process that may result in irregularities within and across various age or grade distributions. Test users often smooth distributions guided by Thurstone assumptions (normality and linearity) to result in norms that adhere to assumptions made about how the data should look. Test…

  6. A simulation study of the electrostriction effects in dielectric elastomer composites containing polarizable inclusions with different spatial distributions.

    PubMed

    Allahyarov, Elshad; Löwen, Hartmut; Zhu, Lei

    2015-12-28

    Controlled actuation of electroactive polymers with embedded high dielectric nanoparticles is theoretically analyzed. If the inclusions are placed randomly in the elastomer body, the composite always contracts along the direction of the applied field. For a simple cubic distribution of inclusions, contraction occurs if the applied field is directed along the [001] direction of the lattice. For inclusions occupying the sites of other lattice structures such as body-centered or face-centered cubic crystals, the composite elongates along the field direction if it is applied along the [001] direction. The stability of the elongation against the imperfectness of the lattice site positions and the distortion ratio of the initial structures are examined. Finite elongation windows show up for the initially distorted body-centered cubic and face-centered cubic crystals as a function of the distortion ratio of the initial structure. The existence of these elongation windows are also predicted from the analysis of the electrostatic energy of the distorted body-centered cubic and face-centered cubic lattice structures. Our results indicate that the electrostriction effect, which is the main contribution to the actuation of low aspect-ratio composites, strongly depends on the geometry of the spatial distribution of nanoparticles, and can thereby largely be tuned. PMID:26592758

  7. On the chemical state and distribution of Zr- and V-based additives in reactive hydride composites.

    PubMed

    Bösenberg, U; Vainio, U; Pranzas, P K; von Colbe, J M Bellosta; Goerigk, G; Welter, E; Dornheim, M; Schreyer, A; Bormann, R

    2009-05-20

    Reactive hydride composites (RHCs) are very promising hydrogen storage materials for future applications due to their reduced reaction enthalpies and high gravimetric capacities. At present, the materials' functionality is limited by the reaction kinetics. A significant positive influence can be observed with addition of transition-metal-based additives. To understand the effect of these additives, the chemical state and changes during the reaction as well as the microstructural distribution were investigated using x-ray absorption near-edge structure (XANES) spectroscopy and anomalous small-angle x-ray scattering (ASAXS). In this work, zirconium- and vanadium-based additives were added to 2LiBH4-MgH2 composites and 2LiH-MgB2 composites and measured in the vicinity of the corresponding absorption edge. The measurements reveal the formation of finely distributed zirconium diboride and vanadium-based nanoparticles. The potential mechanisms for the observed influence on the reaction kinetics are discussed. PMID:19420651

  8. Composition, spatial distribution, and diversity of the bacterial communities in the rumen of cows fed different forages.

    PubMed

    Kong, Yunhong; Teather, Ronald; Forster, Robert

    2010-12-01

    The species composition, distribution, and biodiversity of the bacterial communities in the rumen of cows fed alfalfa or triticale were investigated using 16S rRNA gene clone library analyses. The rumen bacterial community was fractionated and analyzed as three separate fractions: populations in the planktonic, loosely attached to rumen digesta particles, and tightly attached to rumen digesta particles. Six hundred and thirteen operational taxonomic units (OTUs) belonging to 32 genera, 19 families, and nine phyla of the domain Bacteria were identified from 1014 sequenced clones. Four hundred and fifty one of the 613 OTUs were identified as new species. These bacterial sequences were distributed differently among the three fractions in the rumen digesta of cows fed alfalfa or triticale. Chao 1 estimation revealed that, in both communities, the populations tightly attached to particulates were more diverse than the planktonic and those loosely attached to particulates. S-Libshuff detected significant differences in the composition between any two fractions in the rumen of cows with the same diet and between the communities fed alfalfa and triticale diets. The species richness estimated for the communities fed alfalfa and triticale is 1027 and 662, respectively. The diversity of the rumen bacterial community examined in this study is greater than previous studies have demonstrated and the differences in the community composition between two high-fiber diets have implications for sample selection for downstream metagenomics applications. PMID:21044097

  9. Failure models for textile composites

    NASA Technical Reports Server (NTRS)

    Cox, Brian

    1995-01-01

    The goals of this investigation were to: (1) identify mechanisms of failure and determine how the architecture of reinforcing fibers in 3D woven composites controlled stiffness, strength, strain to failure, work of fracture, notch sensitivity, and fatigue life; and (2) to model composite stiffness, strength, and fatigue life. A total of 11 different angle and orthogonal interlock woven composites were examined. Composite properties depended on the weave architecture, the tow size, and the spatial distributions and strength of geometrical flaws. Simple models were developed for elastic properties, strength, and fatigue life. A more complicated stochastic model, called the 'Binary Model,' was developed for damage tolerance and ultimate failure. These 3D woven composites possessed an extraordinary combination of strength, damage tolerance, and notch insensitivity.

  10. Effect of re-melting on particle distribution and interface formation in SiC reinforced 2124Al matrix composite

    SciTech Connect

    Mandal, Durbadal; Viswanathan, Srinath

    2013-12-15

    The interface between metal matrix and ceramic reinforcement particles plays an important role in improving properties of the metal matrix composites. Hence, it is important to find out the interface structure of composite after re-melting. In the present investigation, the 2124Al matrix with 10 wt.% SiC particle reinforced composite was re-melted at 800 °C and 900 °C for 10 min followed by pouring into a permanent mould. The microstructures reveal that the SiC particles are distributed throughout the Al-matrix. The volume fraction of SiC particles varies from top to bottom of the composite plate and the difference increases with the decrease of re-melting temperature. The interfacial structure of re-melted 2124Al–10 wt.%SiC composite was investigated using scanning electron microscopy, an electron probe micro-analyzer, a scanning transmission electron detector fitted with scanning electron microscopy and an X-ray energy dispersive spectrometer. It is found that a thick layer of reaction product is formed at the interface of composite after re-melting. The experimental results show that the reaction products at the interface are associated with high concentration of Cu, Mg, Si and C. At re-melting temperature, liquid Al reacts with SiC to form Al{sub 4}C{sub 3} and Al–Si eutectic phase or elemental Si at the interface. High concentration of Si at the interface indicates that SiC is dissociated during re-melting. The X-ray energy dispersive spectrometer analyses confirm that Mg- and Cu-enrich phases are formed at the interface region. The Mg is segregated at the interface region and formed MgAl{sub 2}O{sub 4} in the presence of oxygen. The several elements identified at the interface region indicate that different types of interfaces are formed in between Al matrix and SiC particles. The Al–Si eutectic phase is formed around SiC particles during re-melting which restricts the SiC dissolution. - Highlights: • Re-melted composite shows homogeneous particle distribution • Thick reaction products are observed at the interface • Carbide is identified at interface due to SiC dissolution at high temperature • Reaction products are also Si enrich phase • Mg and Cu segregated and formed MgAl{sub 2}O{sub 4}, CuMgAl{sub 2} phase at grain boundary.

  11. Mid-infrared spectral variability for compositionally similar asteroids: Implications for asteroid particle size distributions

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Carry, B.; Emery, J.; Hora, J. L.; Cruikshank, D.; Binzel, R. P.; Jackson, J.; Helbert, J.; Maturilli, A.

    2010-06-01

    We report an unexpected variability among mid-infrared spectra (IRTF and Spitzer data) of eight S-type asteroids for which all other remote sensing interpretations (e.g. VNIR spectroscopy, albedo) yield similar compositions. Compositional fitting making use of their mid-IR spectra only yields surprising alternative conclusions: (1) these objects are not "compositionally similar" as the inferred abundances of their main surface minerals (olivine and pyroxene) differ from one another by 35% and (2) carbonaceous chondrite and ordinary chondrite meteorites provide an equally good match to each asteroid spectrum. Following the laboratory work of Ramsey and Christensen (Ramsey, M.S., Christensen, P.R. [1998]. J. Geophys. Res. 103, 577-596), we interpret this variability to be physically caused by differences in surface particle size and/or the effect of space weathering processes. Our results suggest that the observed asteroids must be covered with very fine (<5 ?m) dust that masks some major and most minor spectral features. We speculate that the compositional analysis may be improved with a spectral library containing a wide variety of well characterized spectra (e.g., olivine, orthopyroxene, feldspar, iron, etc.) obtained from very fine powders. In addition to the grain size effect, space weathering processes may contribute as well to the reduction of the spectral contrast. This can be directly tested via new laboratory irradiation experiments.

  12. Damage detection tomography based on guided waves in composite structures using a distributed sensor network

    NASA Astrophysics Data System (ADS)

    Memmolo, Vittorio; Maio, Leandro; Boffa, Natalino Daniele; Monaco, Ernesto; Ricci, Fabrizio

    2016-01-01

    Structural health monitoring (SHM) based on guided waves allows assessing the health of a structure due to the sensitivity to the occurrence of delamination. However, wave propagation presents several complexities for effective damage identification in composite structures. An efficient implementation of a guided wave-based SHM system requires an accurate analysis of collected data to obtain a useful detection. This paper is concerned with the identification of small emerging delaminations in composite structural components using a sparse array of surface ultrasonic transducers. An ultrasonic-guided wave tomography technique focused on impact damage detection in composite plate-like structures is presented. A statistical damage index approach is adopted to interpret the recorded signals, and a subsequent graphic interpolation is implemented to reconstruct the damage appearance. Experimental tests carried out on a typical composite structure demonstrated the effectiveness of the developed technique with the aim to investigate the presence and location of damage using simple imaging reports and a limited number of measurements. A traditional ultrasonic inspection (C-scan) is used to assess the methodology.

  13. Depth distribution and composition of seed banks under different tree layers in a managed temperate forest ecosystem

    NASA Astrophysics Data System (ADS)

    Godefroid, Sandrine; Phartyal, Shyam S.; Koedam, Nico

    2006-05-01

    In the present work we examined the composition and distribution across three soil layers of the buried soil seed bank under three different overstory types ( Fagus sylvatica, Quercus robur, Pinus sylvestris) and in logging areas in a 4383-ha forest in central Belgium. The objectives were: (1) to investigate whether species composition and species richness of soil seed banks are affected by different forest stands; (2) to examine how abundant are habitat-specific forest species in seed banks under different planted tree layers. The study was carried out in stands which are replicated, managed in the same way (even-aged high forest), and growing on the same soil type with the same land-use history. In the investigated area, the seed bank did show significant differences under oak, beech, pine and in logging areas, respectively in terms of size, composition and depth occurrence. All species and layers taken together, the seed bank size ranked as follows: oakwood > beechwood > logging area > pinewood. The same pattern was found for forest species. Seed numbers of Betula pendula, Calluna vulgaris, Dryopteris dilatata and Rubus fruticosus were significantly higher under the beech canopy. Carex remota, Impatiens parviflora and Lotus sp. showed a significantly denser seed bank in logging areas, while Digitalis purpurea seeds were significantly more abundant in soils under the oak canopy. The fact that the seed bank of an originally homogeneous forest varies under different planted stands highlights that a long period of canopy conversion can affect the composition and depth of buried seeds.

  14. Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires

    SciTech Connect

    Li, Qiming; Wang, George T.

    2010-01-01

    The optical properties, indium concentration and distribution, defect morphology, and strain distribution of GaN/InGaN coaxial nanowires grown by metal organic chemical vapor deposition were investigated using spatially resolved cathodoluminescence, scanning transmission electron microscopy, and finite element analysis. The results indicate that InGaN layers with 40% or greater indium incorporation and low defect density can be achieved. The indium distribution in the InGaN shell layer was measured and qualitatively correlated with the calculated strain distribution. The three-dimensional compliance of the GaN nanowire leads to facile strain relaxation in the InGaNheteroepitaxial layer, enabling high indium incorporation and high crystalline quality.

  15. Aerosol Size Distribution, Composition, and Hygroscopicity Measurements During CSTRIPE Using an Aerosol Mass Spectrometer and a Dual Differential Mobility Analyzer

    NASA Astrophysics Data System (ADS)

    Bahreini, R.; Varutbangkul, V.; Conant, W. C.; Flagan, R. C.; Seinfeld, J. H.; Buzorius, G.; Jonsson, H. H.

    2003-12-01

    During July 2003, the CIRPAS Twin Otter aircraft was deployed in the CSTRIPE (Coastal STRatocumulus Imposed Perturbation Experiment) field experiment in order to quantify the effects of aerosols on the microphysics and dynamics of marine stratocumulus clouds. In order to characterize the effects of different aerosol types on stratocumulus clouds, various air masses were sampled, including local fire plumes, pollution over the San Joaquin valley, unperturbed marine stratocumulus clouds, and stratocumulus clouds perturbed by seeding flares. Some research flights were also dedicated to characterize the seeding flares in the clear sky. Measurements of aerosol mass distribution and composition, using an Aerodyne Aerosol Mass Spectrometer (AMS), and size distribution and hygroscopic behavior, using a Dual Differential Mobility Analyzer (Dual DMA) with one column at dry conditions and another at a relative humidity of approximately 70 percent, will be presented here. During a number of in-cloud sampling periods, the Counter-flow Virtual Impactor (CVI) was used to select and dry cloud droplets, which were then analyzed by the AMS and the Dual DMA. The AMS composition measurements showed that sulfate and organics comprised most of the mass of the non-refractory components of the aerosol. The DMA showed a mixture of unimodal and bimodal size distributions in most types of air masses. The air mass over the San Joaquin valley, however, showed strong evidence of freshly nucleated particles, with aerosol number concentrations often above 80,000 cm-3.

  16. Distribution and Stable Isotopic Composition of Amino Acids from Fungal Peptaibiotics: Assessing the Potential for Meteoritic Contamination

    NASA Astrophysics Data System (ADS)

    Elsila, Jamie E.; Callahan, Michael P.; Glavin, Daniel P.; Dworkin, Jason P.; Brückner, Hans

    2011-03-01

    The presence of nonprotein α-dialkyl-amino acids such as α-aminoisobutyric acid (α-AIB) and isovaline (Iva), which are considered to be relatively rare in the terrestrial biosphere, has long been used as an indication of the indigeneity of meteoritic amino acids. However, recent work showing the presence of α-AIB and Iva in peptides produced by a widespread group of filamentous fungi indicates the possibility of a terrestrial biotic source for the α-AIB observed in some meteorites. We measured the amino acid distribution and stable carbon and nitrogen isotopic composition of four α-AIB-containing fungal peptides and compared this data to similar meteoritic measurements. We show that the relatively simple distribution of the C4 and C5 amino acids in fungal peptides is distinct from the complex distribution observed in many carbonaceous chondrites. We also identify potentially diagnostic relationships between the stable isotopic compositions of pairs of amino acids from the fungal peptides that may aid in ruling out fungal contamination as a source of meteoritic amino acids.

  17. Observations of smoke-influenced aerosol during the Yosemite Aerosol Characterization Study: Size distributions and chemical composition

    NASA Astrophysics Data System (ADS)

    McMeeking, G. R.; Kreidenweis, S. M.; Carrico, C. M.; Lee, T.; Collett, J. L.; Malm, W. C.

    2005-05-01

    The Yosemite Aerosol Characterization Study (YACS) took place in Yosemite National Park from 15 July to 5 September 2002, during which time air masses arriving at the site were believed to have been influenced by smoke from numerous wildfires active in the western United States. Physical, optical, and chemical aerosol measurements were made to characterize visibility and to help define aerosol sources contributing to haze in the park, with a particular emphasis on the role of prescribed and wild fires. Measurements of dry aerosol size distributions were made with a differential mobility analyzer (DMA) and an optical particle counter (OPC). An iterative alignment method assuming a range of refractive indices was applied to OPC size distributions to match them to DMA size distributions, returning the real refractive index that yielded the best fit and generating a complete size distribution for 0.04 < Dp < 2 μm. Retrieved dry aerosol real refractive indices generally ranged from 1.56 to 1.59 and were comparable to values estimated from composition measurements. Organic carbon was the dominant aerosol species during the study, particularly during periods identified as smoke impacted. Mie theory was used to determine mass scattering efficiencies (λ = 530 nm) from measured dry size distributions using retrieved refractive indices. These ranged from 3 to 6 m2 g-1, with the highest values occurring during smoke-impacted episodes.

  18. The distribution and life cycle of the dinoflagellate Spatulodinium pseudonoctiluca (Dinophyceae, Noctilucales) in the northeastern English Channel.

    PubMed

    Gmez, Fernando; Souissi, Sami

    2007-03-01

    The distribution of Spatulodinium (= Gymnodinium) pseudonoctiluca (Pouchet) J. Cachon & M. Cachon has been investigated for eight years (1998-2005) in the northeastern English Channel, type locality of the species and its immature stages. The species can be found after the spring diatom bloom from late May to October. The highest abundance was found in June 2004 after the Phaeocystis bloom. Exceptionally, the Phaeocystis bloom was absent in 2005 and only several specimens of S. pseudonoctiluca were observed. The immature and mature stages of Spatulodinium nearly always co-occurred. No other kofoidiniaceans such as Kofoidinium or Pomatodinium were observed. The first stages of the development of Spatulodinium can easily confuse with gymnodiniaceans. The transformation of the stage 'D', which has been described as Gymnodinium lebouriae (= G. fulgens) or Gymnodinium conicum (= G. viridis), into the mature stage, is illustrated. The stage 'D' originates from a cluster of pairs of smaller cells joined by an elongate episome. In the boreal Atlantic Ocean, Spatulodinium pseudonoctiluca, a single species whose life stages are often reported as separate species, is especially adapted to a strongly fluctuant environment. PMID:17434117

  19. Abundance, composition, and distribution of crustacean zooplankton in relation to hypolimnetic oxygen depletion in west-central Lake Erie

    USGS Publications Warehouse

    Heberger, Roy F.; Reynolds, James B.

    1977-01-01

    Samples of crustacean zooplankton were collected monthly in west-central Lake Erie in April and June to October 1968, and in July and August 1970, before and during periods of hypolimnetic dissolved oxygen (DO) depletion. The water column at offshore stations was thermally stratified from June through September 1968, and the hypolimnion contained no DO in mid-August of 1968 or 1970. Composition, abundance, and vertical distribution of crustacean zooplankton changed coincidentally with oxygen depletion. From July to early August, zooplankton abundance dropped 79% in 1968 and 50% in 1970. The declines were attributed largely to a sharp decrease in abundance of planktonic Cyclops bicuspidatus thomasi. Zooplankton composition shifted from mainly cyclopoid copepods in July to mainly cladocerans and copepod nauplii in middle to late August. We believe that mortality of adults and dormancy of copepodites in response to anoxia was the probable reason for the late summer decline in planktonic C. b. thomasi.

  20. Controlling the length scale and distribution of the ductile phase in metallic glass composites through friction stir processing

    NASA Astrophysics Data System (ADS)

    Singh Arora, Harpreet; Mridha, Sanghita; Singh Grewal, Harpreet; Singh, Harpreet; Hofmann, Douglas C.; Mukherjee, Sundeep

    2014-06-01

    We demonstrate the refinement and uniform distribution of the crystalline dendritic phase by friction stir processing (FSP) of titanium based in situ ductile-phase reinforced metallic glass composite. The average size of the dendrites was reduced by almost a factor of five (from 24 μm to 5 μm) for the highest tool rotational speed of 900 rpm. The large inter-connected dendrites become more fragmented with increased circularity after processing. The changes in thermal characteristics were measured by differential scanning calorimetry. The reduction in crystallization enthalpy after processing suggests partial devitrification due to the high strain plastic deformation. FSP resulted in increased hardness and modulus for both the amorphous matrix and the crystalline phase. This is explained by interaction of shear bands in amorphous matrix with the strain-hardened dendritic phase. Our approach offers a new strategy for microstructural design in metallic glass composites.

  1. Distribution of ether lipids and composition of the archaeal community in terrestrial geothermal springs: impact of environmental variables.

    PubMed

    Xie, Wei; Zhang, Chuanlun L; Wang, Jinxiang; Chen, Yufei; Zhu, Yuanqing; de la Torre, José R; Dong, Hailiang; Hartnett, Hilairy E; Hedlund, Brian P; Klotz, Martin G

    2015-05-01

    Archaea can respond to changes in the environment by altering the composition of their membrane lipids, for example, by modification of the abundance and composition of glycerol dialkyl glycerol tetraethers (GDGTs). Here, we investigated the abundance and proportions of polar GDGTs (P-GDGTs) and core GDGTs (C-GDGTs) sampled in different seasons from Tengchong hot springs (Yunnan, China), which encompassed a pH range of 2.5-10.1 and a temperature range of 43.7-93.6°C. The phylogenetic composition of the archaeal community (reanalysed from published work) divided the Archaea in spring sediment samples into three major groups that corresponded with spring pH: acidic, circumneutral and alkaline. Cluster analysis showed correlation between spring pH and the composition of P- and C-GDGTs and archaeal 16S rRNA genes, indicating an intimate link between resident Archaea and the distribution of P- and C-GDGTs in Tengchong hot springs. The distribution of GDGTs in Tengchong springs was also significantly affected by temperature; however, the relationship was weaker than with pH. Analysis of published datasets including samples from Tibet, Yellowstone and the US Great Basin hot springs revealed a similar relationship between pH and GDGT content. Specifically, low pH springs had higher concentrations of GDGTs with high numbers of cyclopentyl rings than neutral and alkaline springs, which is consistent with the predominance of high cyclopentyl ring-characterized Sulfolobales and Thermoplasmatales present in some of the low pH springs. Our study suggests that the resident Archaea in these hot springs are acclimated if not adapted to low pH by their genetic capacity to effect the packing density of their membranes by increasing cyclopentyl rings in GDGTs at the rank of community. PMID:25142282

  2. Evaluation of two fiber optic-based solar collection and distribution systems for advanced space life support.

    PubMed

    Jack, D A; Nakamura, T; Sadler, P; Cuello, J L

    2002-01-01

    Growing plants in an enclosed controlled environment is crucial in developing bioregenerative life-support systems (BLSS) for space applications. The major challenge currently facing a BLSS is the extensive use of highly energy-intensive electric light sources, which leads to substantial energy wastes through heat dissipations by these lamps. An alternative lighting strategy is the use of a solar irradiance collection, transmission, and distribution system (SICTDS). Two types of fiber optic-based SICTDS, a Fresnel-lens Himawari and a parabolic-mirror optical waveguide (OW) lighting system, were evaluated. The overall efficiency for the OW SICTDS of 40.5% exceeded by 75% that for the Himawari of 23.2%. The spectral distributions of the light delivered by the Himawari and the OW SICTDS were almost identical and had practically no difference from that of terrestrial solar radiation. The ratios of photosynthetically active radiation (PAR) to total emitted radiation (k) of 0.39 +/- 0.02 for the Himawari and 0.41 +/- 0.04 for the OW SICTDS were statistically indistinguishable, were not significantly different from that of 0.042 +/- 0.01 for terrestrial solar radiation, and were comparable to that of 0.35 for a high-pressure sodium (HPS) lamp. The coefficients of variation (CV) of 0.34 and 0.39 for PPF distributions, both at 50 mm X 50 mm square grid arrays, corresponding to the Himawari and the OW SICTDS, respectively, were comparable with each other but were both significantly greater than the CV of 0.08 corresponding to the HPS lamp. The average fresh weight or dry weight of lettuce grown in the solar chamber with either the Himawari or the OW SICTDS showed no statistical difference from the average fresh weight or dry weight of lettuce grown in the reference chamber with the HPS lamp. The results of this study suggest that an SICTDS could help reduce the electric power demand in a BLSS. PMID:12807140

  3. Composites

    NASA Astrophysics Data System (ADS)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  4. Synthesis of supported bimetallic nanoparticles with controlled size and composition distributions for active site elucidation

    SciTech Connect

    Hakim, Sikander H.; Sener, Canan; Alba Rubio, Ana C.; Gostanian, Thomas M.; O'neill, Brandon J; Ribeiro, Fabio H.; Miller, Jeffrey T.; Dumesic, James A

    2015-08-01

    Elucidation of active sites in supported bimetallic catalysts is complicated by the high level of dispersity in the nanoparticle size and composition that is inherent in conventional methods of catalyst preparation. We present a synthesis strategy that leads to highly dispersed, bimetallic nanoparticles with uniform particle size and composition by means of controlled surface reactions. We demonstrate the synthesis of three systems, RhMo, PtMo, and RhRe, consisting of a highly reducible metal with an oxophilic promoter. These catalysts are characterized by FTIR, CO chemisorption, STEM/EDS, TPR, and XAS analysis. The catalytic properties of these bimetallic nanoparticles were probed for the selective CO hydrogenolysis of (hydroxymethyl)tetrahydropyran to produce 1,6 hexanediol. Based on the characterization results and reactivity trends, the active sites in the hydrogenolysis reaction are identified to be small ensembles of the more noble metal (Rh, Pt) adjacent to highly reduced moieties of the more oxophilic metal (Mo, Re).

  5. Measurement of internal die pressure distributions during pultrusion of thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Fanucci, Jerome P.; Nolet, Stephen C.; Koppernaes, Christian; Kim, Young R.

    This paper describes the development and use of a thin, disposable pressure sensor designed specifically for monitoring pointwise through-the-thickness consolidation forces developed during composite processing. The unique postage stamp-sized sensor (11.1 mm diameter active gage area and 0.31 mm thickness) can be placed directly at points in or on a laminate where pressure data is desired. The sonsor's small dimensions and low cost permit it to be treated as a disposable item in aerospace and other composite fabrication applications. This paper will illustrate the use of the sensor as a means of measuring the pressures developed inside a die during the pultrusion of a graphite/ULTEM thermoplastic structure, as well as with other pultrusion processing examples.

  6. Distribution and enantiomeric composition of amino acids in the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Engel, M. H.; Nagy, B.

    1982-01-01

    Studies of the amino acid contents and enantiomeric compositions of a single stone from the Murchison meteorite are reported. Water-extracted and 6M HCl-extracted samples from the meteorite interior of meteorite fragments were analyzed by gas chromatography and combined gas chromatography-chemical ionization mass spectrometry. Examination of the D/L ratios of glutamic acid, aspartic acid, proline, leucine and alanine reveals those amino acids extractable by water to be partially racemized, whereas the acid-extracted amino acids were less racemized. The amino acid composition of the stone is similar to those previously reported, including the absence of serine, threonine, tyrosine phenylalanine and methionine and the presence of unusual amino acids including such as isovaline, alpha-aminoisobutyric acid and pseudoleucine. It is concluded that the most likely mechanism accounting for the occurrence of nonracemic amino acid mixtures in the Murchison meteorite is by extraterrestrial stereoselective synthesis or decomposition reactions.

  7. Effect of reaction mixture composition and silica source on size distribution of zeolite X crystals

    NASA Astrophysics Data System (ADS)

    Tekin, Rumeysa; Bac, Nurcan; Warzywoda, Juliusz; Sacco, Albert

    2015-02-01

    Zeolite X crystals were synthesized by hydrothermal crystallization from gels with different compositions. The syntheses were performed at 95 C using different silica sources such as sodium metasilicate anhydrous, sodium metasilicate pentahydrate, silicate solution and Cab-O-Sil. Triethanolamine was used in some syntheses in order to grow large crystals. Zeolite X crystals with diameters in the range of 1-220 ?m were obtained, and Cab-O-Sil in concert with triethanolamine yielded the largest crystals.

  8. The Distribution and Chemical Composition of Particles in a Macrotidal Estuary

    NASA Astrophysics Data System (ADS)

    Turner, A.; Millward, G. E.; Tyler, A. O.

    1994-01-01

    Spatial and short-term temporal measurements of hydrographic parameters [salinity and concentration of suspended particulate matter (SPM)] and sediment characteristics (specific surface area, major and trace metals, C and N, 137 Cs and 241Am) have been undertaken in a rapidly accreting macrotidal estuary (Dee Estuary, north-east Wales). The composition of the sediment indicates a dominance of marine material in the estuary and that fine SPM is fluvial in origin, admixing in the water column with coarse, tidally suspended bed material. The time-variable composition of SPM in the upper estuary, where tidal energy converges, was tested against a particle mixing model incorporating the compositions of permanently suspended and temporarily suspended populations operationally fractionated according to settling velocities. Agreement with the model was reasonable but suggested additional processes such as selective resuspension and/or advection of particle types. The behaviour and characteristics of different sediment populations are discussed in the context of the cycling and fluxes of particle-bound constituents and sorptive removal of dissolved constituents, and a flux model for the accumulation of 137Cs in the estuary is developed.

  9. Particles in the lower troposphere over the High Plains of the United States. I - Size distributions, elemental compositions and morphologies

    NASA Technical Reports Server (NTRS)

    Hobbs, P. V.; Radke, W. F.; Bowdle, D. A.

    1985-01-01

    Airborne measurements of particle size distributions obtained during the spring and summer of 1975-1976 at various locations in the high plains of the U.S. are presented. The instrumentation and techniques used to collect the data are described. Particle number, surface area, and volume distribution are measured; differences in particle concentrations are investigated. Variables in particle size are related to changes in strength of ground sources of Aitken nuclei, age of the particle population, and presence or absence of rain. An accumulation mode between particles diameters of 0.1-1 micron, a coarse particle mode between particle diameters between 10-20 microns, and a nucleation mode at particle diameters less than 0.1 micron are detected. The control of the accommodation and coarse particle modes and their influence on particle concentration are studied. The elemental composition of the particles is analyzed and the morphologies are examined with an electron scanner microscope.

  10. Search for quark compositeness in dijet angular distributions from pp collisions at √{s} = 7{ } TeV

    NASA Astrophysics Data System (ADS)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hammer, J.; Hoch, M.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Krammer, M.; Liko, D.; Mikulec, I.; Pernicka, M.; Rahbaran, B.; Rohringer, C.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Teischinger, F.; Wagner, P.; Waltenberger, W.; Walzel, G.; Widl, E.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Bansal, S.; Benucci, L.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Maes, T.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Charaf, O.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hammad, G. H.; Hreus, T.; Léonard, A.; Marage, P. E.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wickens, J.; Adler, V.; Beernaert, K.; Cimmino, A.; Costantini, S.; Garcia, G.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Vanelderen, L.; Verwilligen, P.; Walsh, S.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Ceard, L.; De Favereau De Jeneret, J.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Grégoire, G.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Schul, N.; Beliy, N.; Caebergs, T.; Daubie, E.; Alves, G. A.; De Jesus Damiao, D.; Martins, T.; Pol, M. E.; Souza, M. H. G.; Aldá Júnior, W. L.; Carvalho, W.; Custódio, A.; Da Costa, E. M.; De Oliveira Martins, C.; Fonseca De Souza, S.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Oguri, V.; Prado Da Silva, W. L.; Santoro, A.; Silva Do Amaral, S. 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C.; Godinovic, N.; Lelas, D.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Dzelalija, M.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Morovic, S.; Attikis, A.; Galanti, M.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Ellithi Kamel, A.; Khalil, S.; Mahmoud, M. A.; Radi, A.; Hektor, A.; Kadastik, M.; Müntel, M.; Raidal, M.; Rebane, L.; Tiko, A.; Azzolini, V.; Eerola, P.; Fedi, G.; Voutilainen, M.; Czellar, S.; Härkönen, J.; Heikkinen, A.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Banzuzi, K.; Korpela, A.; Tuuva, T.; Sillou, D.; Besancon, M.; Choudhury, S.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. 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A.; Sonnenschein, L.; Steggemann, J.; Teyssier, D.; Weber, M.; Bontenackels, M.; Cherepanov, V.; Davids, M.; Flügge, G.; Geenen, H.; Geisler, M.; Haj Ahmad, W.; Hoehle, F.; Kargoll, B.; Kress, T.; Kuessel, Y.; Linn, A.; Nowack, A.; Perchalla, L.; Pooth, O.; Rennefeld, J.; Sauerland, P.; Stahl, A.; Zoeller, M. H.; Aldaya Martin, M.; Behrenhoff, W.; Behrens, U.; Bergholz, M.; Bethani, A.; Borras, K.; Cakir, A.; Campbell, A.; Castro, E.; Dammann, D.; Eckerlin, G.; Eckstein, D.; Flossdorf, A.; Flucke, G.; Geiser, A.; Hauk, J.; Jung, H.; Kasemann, M.; Katsas, P.; Kleinwort, C.; Kluge, H.; Knutsson, A.; Krämer, M.; Krücker, D.; Kuznetsova, E.; Lange, W.; Lohmann, W.; Lutz, B.; Mankel, R.; Marfin, I.; Marienfeld, M.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Olzem, J.; Petrukhin, A.; Pitzl, D.; Raspereza, A.; Ribeiro Cipriano, P. 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R.; Kuhr, T.; Martschei, D.; Mueller, S.; Müller, Th.; Niegel, M.; Oberst, O.; Oehler, A.; Ott, J.; Peiffer, T.; Quast, G.; Rabbertz, K.; Ratnikov, F.; Ratnikova, N.; Renz, M.; Röcker, S.; Saout, C.; Scheurer, A.; Schieferdecker, P.; Schilling, F.-P.; Schmanau, M.; Schott, G.; Simonis, H. J.; Stober, F. M.; Troendle, D.; Wagner-Kuhr, J.; Weiler, T.; Zeise, M.; Ziebarth, E. B.; Daskalakis, G.; Geralis, T.; Kesisoglou, S.; Kyriakis, A.; Loukas, D.; Manolakos, I.; Markou, A.; Markou, C.; Mavrommatis, C.; Ntomari, E.; Gouskos, L.; Mertzimekis, T. J.; Panagiotou, A.; Saoulidou, N.; Stiliaris, E.; Evangelou, I.; Foudas, C.; Kokkas, P.; Manthos, N.; Papadopoulos, I.; Patras, V.; Triantis, F. A.; Aranyi, A.; Bencze, G.; Boldizsar, L.; Hajdu, C.; Hidas, P.; Horvath, D.; Kapusi, A.; Krajczar, K.; Sikler, F.; Vesztergombi, G.; Beni, N.; Molnar, J.; Palinkas, J.; Szillasi, Z.; Veszpremi, V.; Karancsi, J.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Beri, S. 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M.; Rovelli, T.; Siroli, G.; Travaglini, R.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Frosali, S.; Gallo, E.; Gonzi, S.; Meschini, M.; Paoletti, S.; Sguazzoni, G.; Tropiano, A.; Benussi, L.; Bianco, S.; Colafranceschi, S.; Fabbri, F.; Piccolo, D.; Fabbricatore, P.; Musenich, R.; Benaglia, A.; De Guio, F.; Di Matteo, L.; Fiorendi, S.; Gennai, S.; Ghezzi, A.; Malvezzi, S.; Manzoni, R. A.; Martelli, A.; Massironi, A.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Ragazzi, S.; Redaelli, N.; Sala, S.; Tabarelli de Fatis, T.; Buontempo, S.; Carrillo Montoya, C. A.; Cavallo, N.; De Cosa, A.; Dogangun, O.; Fabozzi, F.; Iorio, A. O. M.; Lista, L.; Merola, M.; Paolucci, P.; Azzi, P.; Bacchetta, N.; Bellan, P.; Bisello, D.; Branca, A.; Carlin, R.; Checchia, P.; Dorigo, T.; Dosselli, U.; Fanzago, F.; Gasparini, F.; Gasparini, U.; Gozzelino, A.; Kanishchev, K.; Lacaprara, S.; Lazzizzera, I.; Margoni, M.; Mazzucato, M.; Meneguzzo, A. T.; Nespolo, M.; Perrozzi, L.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Tosi, M.; Vanini, S.; Zotto, P.; Zumerle, G.; Baesso, P.; Berzano, U.; Ratti, S. P.; Riccardi, C.; Torre, P.; Vitulo, P.; Viviani, C.; Biasini, M.; Bilei, G. M.; Caponeri, B.; Fanò, L.; Lariccia, P.; Lucaroni, A.; Mantovani, G.; Menichelli, M.; Nappi, A.; Romeo, F.; Santocchia, A.; Taroni, S.; Valdata, M.; Azzurri, P.; Bagliesi, G.; Boccali, T.; Broccolo, G.; Castaldi, R.; D'Agnolo, R. T.; Dell'Orso, R.; Fiori, F.; Foà, L.; Giassi, A.; Kraan, A.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Palmonari, F.; Rizzi, A.; Serban, A. 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A.; Shoaib, M.; Brona, G.; Cwiok, M.; Dominik, W.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Bialkowska, H.; Boimska, B.; Frueboes, T.; Gokieli, R.; Górski, M.; Kazana, M.; Nawrocki, K.; Romanowska-Rybinska, K.; Szleper, M.; Wrochna, G.; Zalewski, P.; Almeida, N.; Bargassa, P.; David, A.; Faccioli, P.; Ferreira Parracho, P. G.; Gallinaro, M.; Musella, P.; Nayak, A.; Pela, J.; Ribeiro, P. Q.; Seixas, J.; Varela, J.; Vischia, P.; Afanasiev, S.; Belotelov, I.; Bunin, P.; Golutvin, I.; Gorbunov, I.; Karjavin, V.; Konoplyanikov, V.; Kozlov, G.; Lanev, A.; Moisenz, P.; Palichik, V.; Perelygin, V.; Savina, M.; Shmatov, S.; Smirnov, V.; Volodko, A.; Zarubin, A.; Evstyukhin, S.; Golovtsov, V.; Ivanov, Y.; Kim, V.; Levchenko, P.; Murzin, V.; Oreshkin, V.; Smirnov, I.; Sulimov, V.; Uvarov, L.; Vavilov, S.; Vorobyev, A.; Vorobyev, An.; Andreev, Yu.; Dermenev, A.; Gninenko, S.; Golubev, N.; Kirsanov, M.; Krasnikov, N.; Matveev, V.; Pashenkov, A.; Toropin, A.; Troitsky, S.; Epshteyn, V.; Erofeeva, M.; Gavrilov, V.; Kossov, M.; Krokhotin, A.; Lychkovskaya, N.; Popov, V.; Safronov, G.; Semenov, S.; Stolin, V.; Vlasov, E.; Zhokin, A.; Belyaev, A.; Boos, E.; Dubinin, M.; Dudko, L.; Ershov, A.; Gribushin, A.; Kodolova, O.; Lokhtin, I.; Markina, A.; Obraztsov, S.; Perfilov, M.; Petrushanko, S.; Sarycheva, L.; Savrin, V.; Snigirev, A.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Leonidov, A.; Mesyats, G.; Rusakov, S. V.; Vinogradov, A.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Grishin, V.; Kachanov, V.; Konstantinov, D.; Korablev, A.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Tourtchanovitch, L.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Djordjevic, M.; Ekmedzic, M.; Krpic, D.; Milosevic, J.; Aguilar-Benitez, M.; Alcaraz Maestre, J.; Arce, P.; Battilana, C.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Diez Pardos, C.; Domínguez Vázquez, D.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Ferrando, A.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Merino, G.; Puerta Pelayo, J.; Redondo, I.; Romero, L.; Santaolalla, J.; Soares, M. S.; Willmott, C.; Albajar, C.; Codispoti, G.; de Trocóniz, J. F.; Cuevas, J.; Fernandez Menendez, J.; Folgueras, S.; Gonzalez Caballero, I.; Lloret Iglesias, L.; Vizan Garcia, J. M.; Brochero Cifuentes, J. A.; Cabrillo, I. J.; Calderon, A.; Chuang, S. H.; Duarte Campderros, J.; Felcini, M.; Fernandez, M.; Gomez, G.; Gonzalez Sanchez, J.; Jorda, C.; Lobelle Pardo, P.; Lopez Virto, A.; Marco, J.; Marco, R.; Martinez Rivero, C.; Matorras, F.; Munoz Sanchez, F. J.; Piedra Gomez, J.; Rodrigo, T.; Rodríguez-Marrero, A. Y.; Ruiz-Jimeno, A.; Scodellaro, L.; Sobron Sanudo, M.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Auzinger, G.; Baillon, P.; Ball, A. H.; Barney, D.; Bernet, C.; Bialas, W.; Bianchi, G.; Bloch, P.; Bocci, A.; Breuker, H.; Bunkowski, K.; Camporesi, T.; Cerminara, G.; Christiansen, T.; Coarasa Perez, J. A.; Curé, B.; D'Enterria, D.; De Roeck, A.; Di Guida, S.; Dobson, M.; Dupont-Sagorin, N.; Elliott-Peisert, A.; Frisch, B.; Funk, W.; Gaddi, A.; Georgiou, G.; Gerwig, H.; Giffels, M.; Gigi, D.; Gill, K.; Giordano, D.; Giunta, M.; Glege, F.; Gomez-Reino Garrido, R.; Govoni, P.; Gowdy, S.; Guida, R.; Guiducci, L.; Hansen, M.; Harris, P.; Hartl, C.; Harvey, J.; Hegner, B.; Hinzmann, A.; Hoffmann, H. F.; Innocente, V.; Janot, P.; Kaadze, K.; Karavakis, E.; Kousouris, K.; Lecoq, P.; Lenzi, P.; Lourenço, C.; Mäki, T.; Malberti, M.; Malgeri, L.; Mannelli, M.; Masetti, L.; Mavromanolakis, G.; Meijers, F.; Mersi, S.; Meschi, E.; Moser, R.; Mozer, M. U.; Mulders, M.; Nesvold, E.; Nguyen, M.; Orimoto, T.; Orsini, L.; Palencia Cortezon, E.; Perez, E.; Petrilli, A.; Pfeiffer, A.; Pierini, M.; Pimiä, M.; Piparo, D.; Polese, G.; Quertenmont, L.; Racz, A.; Reece, W.; Rodrigues Antunes, J.; Rolandi, G.; Rommerskirchen, T.; Rovelli, C.; Rovere, M.; Sakulin, H.; Santanastasio, F.; Schäfer, C.; Schwick, C.; Segoni, I.; Sharma, A.; Siegrist, P.; Silva, P.; Simon, M.; Sphicas, P.; Spiga, D.; Spiropulu, M.; Stoye, M.; Tsirou, A.; Veres, G. I.; Vichoudis, P.; Wöhri, H. K.; Worm, S. D.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Gabathuler, K.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; König, S.; Kotlinski, D.; Langenegger, U.; Meier, F.; Renker, D.; Rohe, T.; Sibille, J.; Bäni, L.; Bortignon, P.; Buchmann, M. A.; Casal, B.; Chanon, N.; Chen, Z.; Deisher, A.; Dissertori, G.; Dittmar, M.; Dünser, M.; Eugster, J.; Freudenreich, K.; Grab, C.; Lecomte, P.; Lustermann, W.; Martinez Ruiz del Arbol, P.; Mohr, N.; Moortgat, F.; Nägeli, C.; Nef, P.; Nessi-Tedaldi, F.; Pape, L.; Pauss, F.; Peruzzi, M.; Ronga, F. J.; Rossini, M.; Sala, L.; Sanchez, A. K.; Sawley, M.-C.; Starodumov, A.; Stieger, B.; Takahashi, M.; Tauscher, L.; Thea, A.; Theofilatos, K.; Treille, D.; Urscheler, C.; Wallny, R.; Weber, H. A.; Wehrli, L.; Weng, J.; Aguilo, E.; Amsler, C.; Chiochia, V.; De Visscher, S.; Favaro, C.; Ivova Rikova, M.; Millan Mejias, B.; Otiougova, P.; Robmann, P.; Snoek, H.; Verzetti, M.; Chang, Y. H.; Chen, K. H.; Kuo, C. M.; Li, S. W.; Lin, W.; Liu, Z. K.; Lu, Y. J.; Mekterovic, D.; Volpe, R.; Yu, S. S.; Bartalini, P.; Chang, P.; Chang, Y. H.; Chang, Y. W.; Chao, Y.; Chen, K. F.; Dietz, C.; Grundler, U.; Hou, W.-S.; Hsiung, Y.; Kao, K. Y.; Lei, Y. J.; Lu, R.-S.; Majumder, D.; Petrakou, E.; Shi, X.; Shiu, J. G.; Tzeng, Y. M.; Wan, X.; Wang, M.; Adiguzel, A.; Bakirci, M. N.; Cerci, S.; Dozen, C.; Dumanoglu, I.; Eskut, E.; Girgis, S.; Gokbulut, G.; Hos, I.; Kangal, E. E.; Karapinar, G.; Kayis Topaksu, A.; Onengut, G.; Ozdemir, K.; Ozturk, S.; Polatoz, A.; Sogut, K.; Sunar Cerci, D.; Tali, B.; Topakli, H.; Uzun, D.; Vergili, L. N.; Vergili, M.; Akin, I. V.; Aliev, T.; Bilin, B.; Bilmis, S.; Deniz, M.; Gamsizkan, H.; Guler, A. M.; Ocalan, K.; Ozpineci, A.; Serin, M.; Sever, R.; Surat, U. E.; Yalvac, M.; Yildirim, E.; Zeyrek, M.; Deliomeroglu, M.; Gülmez, E.; Isildak, B.; Kaya, M.; Kaya, O.; Ozkorucuklu, S.; Sonmez, N.; Levchuk, L.; Bostock, F.; Brooke, J. J.; Clement, E.; Cussans, D.; Flacher, H.; Frazier, R.; Goldstein, J.; Grimes, M.; Heath, G. P.; Heath, H. F.; Kreczko, L.; Metson, S.; Newbold, D. M.; Nirunpong, K.; Poll, A.; Senkin, S.; Smith, V. J.; Williams, T.; Basso, L.; Bell, K. W.; Belyaev, A.; Brew, C.; Brown, R. M.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Jackson, J.; Kennedy, B. W.; Olaiya, E.; Petyt, D.; RadburnSmith, B. C.; Shepherd-Themistocleous, C. H.; Tomalin, I. R.; Womersley, W. J.; Bainbridge, R.; Ball, G.; Beuselinck, R.; Buchmuller, O.; Colling, D.; Cripps, N.; Cutajar, M.; Dauncey, P.; Davies, G.; Della Negra, M.; Ferguson, W.; Fulcher, J.; Futyan, D.; Gilbert, A.; Guneratne Bryer, A.; Hall, G.; Hatherell, Z.; Hays, J.; Iles, G.; Jarvis, M.; Karapostoli, G.; Lyons, L.; Magnan, A.-M.; Marrouche, J.; Mathias, B.; Nandi, R.; Nash, J.; Nikitenko, A.; Papageorgiou, A.; Pesaresi, M.; Petridis, K.; Pioppi, M.; Raymond, D. M.; Rogerson, S.; Rompotis, N.; Rose, A.; Ryan, M. J.; Seez, C.; Sharp, P.; Sparrow, A.; Tapper, A.; Tourneur, S.; Vazquez Acosta, M.; Virdee, T.; Wakefield, S.; Wardle, N.; Wardrope, D.; Whyntie, T.; Barrett, M.; Chadwick, M.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Leslie, D.; Martin, W.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Hatakeyama, K.; Liu, H.; Scarborough, T.; Henderson, C.; Avetisyan, A.; Bose, T.; Carrera Jarrin, E.; Fantasia, C.; Heister, A.; St. John, J.; Lawson, P.; Lazic, D.; Rohlf, J.; Sperka, D.; Sulak, L.; Bhattacharya, S.; Cutts, D.; Ferapontov, A.; Heintz, U.; Jabeen, S.; Kukartsev, G.; Landsberg, G.; Luk, M.; Narain, M.; Nguyen, D.; Segala, M.; Sinthuprasith, T.; Speer, T.; Tsang, K. V.; Breedon, R.; Breto, G.; Calderon De La Barca Sanchez, M.; Caulfield, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Dolen, J.; Erbacher, R.; Gardner, M.; Houtz, R.; Ko, W.; Kopecky, A.; Lander, R.; Mall, O.; Miceli, T.; Nelson, R.; Pellett, D.; Robles, J.; Rutherford, B.; Searle, M.; Smith, J.; Squires, M.; Tripathi, M.; Vasquez Sierra, R.; Andreev, V.; Arisaka, K.; Cline, D.; Cousins, R.; Duris, J.; Erhan, S.; Everaerts, P.; Farrell, C.; Hauser, J.; Ignatenko, M.; Jarvis, C.; Plager, C.; Rakness, G.; Schlein, P.; Tucker, J.; Valuev, V.; Weber, M.; Babb, J.; Clare, R.; Ellison, J.; Gary, J. W.; Giordano, F.; Hanson, G.; Jeng, G. Y.; Liu, H.; Long, O. R.; Luthra, A.; Nguyen, H.; Paramesvaran, S.; Sturdy, J.; Sumowidagdo, S.; Wilken, R.; Wimpenny, S.; Andrews, W.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; Evans, D.; Golf, F.; Holzner, A.; Kelley, R.; Lebourgeois, M.; Letts, J.; Macneill, I.; Mangano, B.; Padhi, S.; Palmer, C.; Petrucciani, G.; Pi, H.; Pieri, M.; Ranieri, R.; Sani, M.; Sfiligoi, I.; Sharma, V.; Simon, S.; Sudano, E.; Tadel, M.; Tu, Y.; Vartak, A.; Wasserbaech, S.; Würthwein, F.; Yagil, A.; Yoo, J.; Barge, D.; Bellan, R.; Campagnari, C.; D'Alfonso, M.; Danielson, T.; Flowers, K.; Geffert, P.; Incandela, J.; Justus, C.; Kalavase, P.; Koay, S. A.; Kovalskyi, D.; Krutelyov, V.; Lowette, S.; Mccoll, N.; Pavlunin, V.; Rebassoo, F.; Ribnik, J.; Richman, J.; Rossin, R.; Stuart, D.; To, W.; Vlimant, J. R.; West, C.; Apresyan, A.; Bornheim, A.; Bunn, J.; Chen, Y.; Di Marco, E.; Duarte, J.; Gataullin, M.; Ma, Y.; Mott, A.; Newman, H. B.; Rogan, C.; Timciuc, V.; Traczyk, P.; Veverka, J.; Wilkinson, R.; Yang, Y.; Zhu, R. Y.; Akgun, B.; Carroll, R.; Ferguson, T.; Iiyama, Y.; Jang, D. W.; Jun, S. Y.; Liu, Y. F.; Paulini, M.; Russ, J.; Vogel, H.; Vorobiev, I.; Cumalat, J. P.; Dinardo, M. E.; Drell, B. R.; Edelmaier, C. J.; Ford, W. T.; Gaz, A.; Heyburn, B.; Luiggi Lopez, E.; Nauenberg, U.; Smith, J. G.; Stenson, K.; Ulmer, K. A.; Wagner, S. R.; Zang, S. L.; Agostino, L.; Alexander, J.; Chatterjee, A.; Eggert, N.; Gibbons, L. K.; Heltsley, B.; Hopkins, W.; Khukhunaishvili, A.; Kreis, B.; Mirman, N.; Nicolas Kaufman, G.; Patterson, J. R.; Puigh, D.; Ryd, A.; Salvati, E.; Sun, W.; Teo, W. D.; Thom, J.; Thompson, J.; Vaughan, J.; Weng, Y.; Winstrom, L.; Wittich, P.; Biselli, A.; Cirino, G.; Winn, D.; Abdullin, S.; Albrow, M.; Anderson, J.; Apollinari, G.; Atac, M.; Bakken, J. A.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bloch, I.; Burkett, K.; Butler, J. N.; Chetluru, V.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Cooper, W.; Eartly, D. P.; Elvira, V. D.; Esen, S.; Fisk, I.; Freeman, J.; Gao, Y.; Gottschalk, E.; Green, D.; Gutsche, O.; Hanlon, J.; Harris, R. M.; Hirschauer, J.; Hooberman, B.; Jensen, H.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kunori, S.; Kwan, S.; Leonidopoulos, C.; Lincoln, D.; Lipton, R.; Lykken, J.; Maeshima, K.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Miao, T.; Mishra, K.; Mrenna, S.; Musienko, Y.; Newman-Holmes, C.; O'Dell, V.; Pivarski, J.; Pordes, R.; Prokofyev, O.; Schwarz, T.; Sexton-Kennedy, E.; Sharma, S.; Spalding, W. J.; Spiegel, L.; Tan, P.; Taylor, L.; Tkaczyk, S.; Uplegger, L.; Vaandering, E. W.; Vidal, R.; Whitmore, J.; Wu, W.; Yang, F.; Yumiceva, F.; Yun, J. C.; Acosta, D.; Avery, P.; Bourilkov, D.; Chen, M.; Das, S.; De Gruttola, M.; Di Giovanni, G. P.; Dobur, D.; Drozdetskiy, A.; Field, R. D.; Fisher, M.; Fu, Y.; Furic, I. K.; Gartner, J.; Goldberg, S.; Hugon, J.; Kim, B.; Konigsberg, J.; Korytov, A.; Kropivnitskaya, A.; Kypreos, T.; Low, J. F.; Matchev, K.; Milenovic, P.; Mitselmakher, G.; Muniz, L.; Remington, R.; Rinkevicius, A.; Schmitt, M.; Scurlock, B.; Sellers, P.; Skhirtladze, N.; Snowball, M.; Wang, D.; Yelton, J.; Zakaria, M.; Gaultney, V.; Lebolo, L. M.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Adams, T.; Askew, A.; Bochenek, J.; Chen, J.; Diamond, B.; Gleyzer, S. V.; Haas, J.; Hagopian, S.; Hagopian, V.; Jenkins, M.; Johnson, K. F.; Prosper, H.; Sekmen, S.; Veeraraghavan, V.; Weinberg, M.; Baarmand, M. M.; Dorney, B.; Hohlmann, M.; Kalakhety, H.; Vodopiyanov, I.; Adams, M. R.; Anghel, I. M.; Apanasevich, L.; Bai, Y.; Bazterra, V. E.; Betts, R. R.; Callner, J.; Cavanaugh, R.; Dragoiu, C.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Khalatyan, S.; Kunde, G. J.; Lacroix, F.; Malek, M.; O'Brien, C.; Silkworth, C.; Silvestre, C.; Strom, D.; Varelas, N.; Akgun, U.; Albayrak, E. A.; Bilki, B.; Clarida, W.; Duru, F.; Griffiths, S.; Lae, C. K.; McCliment, E.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Newsom, C. R.; Norbeck, E.; Olson, J.; Onel, Y.; Ozok, F.; Sen, S.; Tiras, E.; Wetzel, J.; Yetkin, T.; Yi, K.; Barnett, B. A.; Blumenfeld, B.; Bolognesi, S.; Bonato, A.; Eskew, C.; Fehling, D.; Giurgiu, G.; Gritsan, A. V.; Guo, Z. J.; Hu, G.; Maksimovic, P.; Rappoccio, S.; Swartz, M.; Tran, N. V.; Whitbeck, A.; Baringer, P.; Bean, A.; Benelli, G.; Grachov, O.; Kenny, R. P.; Murray, M.; Noonan, D.; Sanders, S.; Stringer, R.; Tinti, G.; Wood, J. S.; Zhukova, V.; Barfuss, A. F.; Bolton, T.; Chakaberia, I.; Ivanov, A.; Khalil, S.; Makouski, M.; Maravin, Y.; Shrestha, S.; Svintradze, I.; Gronberg, J.; Lange, D.; Wright, D.; Baden, A.; Boutemeur, M.; Calvert, B.; Eno, S. C.; Gomez, J. A.; Hadley, N. J.; Kellogg, R. G.; Kirn, M.; Kolberg, T.; Lu, Y.; Mignerey, A. C.; Peterman, A.; Rossato, K.; Rumerio, P.; Skuja, A.; Temple, J.; Tonjes, M. B.; Tonwar, S. C.; Twedt, E.; Alver, B.; Bauer, G.; Bendavid, J.; Busza, W.; Butz, E.; Cali, I. A.; Chan, M.; Dutta, V.; Gomez Ceballos, G.; Goncharov, M.; Hahn, K. A.; Kim, Y.; Klute, M.; Lee, Y.-J.; Li, W.; Luckey, P. D.; Ma, T.; Nahn, S.; Paus, C.; Ralph, D.; Roland, C.; Roland, G.; Rudolph, M.; Stephans, G. S. F.; Stöckli, F.; Sumorok, K.; Sung, K.; Velicanu, D.; Wenger, E. A.; Wolf, R.; Wyslouch, B.; Xie, S.; Yang, M.; Yilmaz, Y.; Yoon, A. S.; Zanetti, M.; Cooper, S. I.; Cushman, P.; Dahmes, B.; De Benedetti, A.; Franzoni, G.; Gude, A.; Haupt, J.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Mans, J.; Pastika, N.; Rekovic, V.; Rusack, R.; Sasseville, M.; Singovsky, A.; Tambe, N.; Turkewitz, J.; Cremaldi, L. M.; Godang, R.; Kroeger, R.; Perera, L.; Rahmat, R.; Sanders, D. A.; Summers, D.; Avdeeva, E.; Bloom, K.; Bose, S.; Butt, J.; Claes, D. R.; Dominguez, A.; Eads, M.; Jindal, P.; Keller, J.; Kravchenko, I.; Lazo-Flores, J.; Malbouisson, H.; Malik, S.; Snow, G. R.; Baur, U.; Godshalk, A.; Iashvili, I.; Jain, S.; Kharchilava, A.; Kumar, A.; Shipkowski, S. P.; Smith, K.; Wan, Z.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Trocino, D.; Wood, D.; Zhang, J.; Anastassov, A.; Kubik, A.; Mucia, N.; Odell, N.; Ofierzynski, R. A.; Pollack, B.; Pozdnyakov, A.; Schmitt, M.; Stoynev, S.; Velasco, M.; Won, S.; Antonelli, L.; Berry, D.; Brinkerhoff, A.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kolb, J.; Lannon, K.; Luo, W.; Lynch, S.; Marinelli, N.; Morse, D. M.; Pearson, T.; Ruchti, R.; Slaunwhite, J.; Valls, N.; Wayne, M.; Wolf, M.; Ziegler, J.; Bylsma, B.; Durkin, L. S.; Hill, C.; Killewald, P.; Kotov, K.; Ling, T. Y.; Rodenburg, M.; Vuosalo, C.; Williams, G.; Adam, N.; Berry, E.; Elmer, P.; Gerbaudo, D.; Halyo, V.; Hebda, P.; Hegeman, J.; Hunt, A.; Laird, E.; Lopes Pegna, D.; Lujan, P.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Piroué, P.; Quan, X.; Raval, A.; Saka, H.; Stickland, D.; Tully, C.; Werner, J. S.; Zuranski, A.; Acosta, J. G.; Huang, X. T.; Lopez, A.; Mendez, H.; Oliveros, S.; Ramirez Vargas, J. E.; Zatserklyaniy, A.; Alagoz, E.; Barnes, V. E.; Benedetti, D.; Bolla, G.; Borrello, L.; Bortoletto, D.; De Mattia, M.; Everett, A.; Gutay, L.; Hu, Z.; Jones, M.; Koybasi, O.; Kress, M.; Laasanen, A. T.; Leonardo, N.; Maroussov, V.; Merkel, P.; Miller, D. H.; Neumeister, N.; Shipsey, I.; Silvers, D.; Svyatkovskiy, A.; Vidal Marono, M.; Yoo, H. D.; Zablocki, J.; Zheng, Y.; Guragain, S.; Parashar, N.; Adair, A.; Boulahouache, C.; Cuplov, V.; Ecklund, K. M.; Geurts, F. J. M.; Padley, B. P.; Redjimi, R.; Roberts, J.; Zabel, J.; Betchart, B.; Bodek, A.; Chung, Y. S.; Covarelli, R.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Garcia-Bellido, A.; Goldenzweig, P.; Gotra, Y.; Han, J.; Harel, A.; Miner, D. C.; Petrillo, G.; Sakumoto, W.; Vishnevskiy, D.; Zielinski, M.; Bhatti, A.; Ciesielski, R.; Demortier, L.; Goulianos, K.; Lungu, G.; Malik, S.; Mesropian, C.; Arora, S.; Atramentov, O.; Barker, A.; Chou, J. P.; Contreras-Campana, C.; Contreras-Campana, E.; Duggan, D.; Ferencek, D.; Gershtein, Y.; Gray, R.; Halkiadakis, E.; Hidas, D.; Hits, D.; Lath, A.; Panwalkar, S.; Park, M.; Patel, R.; Richards, A.; Rose, K.; Salur, S.; Schnetzer, S.; Seitz, C.; Somalwar, S.; Stone, R.; Thomas, S.; Cerizza, G.; Hollingsworth, M.; Spanier, S.; Yang, Z. C.; York, A.; Eusebi, R.; Flanagan, W.; Gilmore, J.; Kamon, T.; Khotilovich, V.; Montalvo, R.; Osipenkov, I.; Pakhotin, Y.; Perloff, A.; Roe, J.; Safonov, A.; Sakuma, T.; Sengupta, S.; Suarez, I.; Tatarinov, A.; Toback, D.; Akchurin, N.; Bardak, C.; Damgov, J.; Dudero, P. R.; Jeong, C.; Kovitanggoon, K.; Lee, S. W.; Libeiro, T.; Mane, P.; Roh, Y.; Sill, A.; Volobouev, I.; Wigmans, R.; Appelt, E.; Brownson, E.; Engh, D.; Florez, C.; Gabella, W.; Gurrola, A.; Issah, M.; Johns, W.; Kurt, P.; Maguire, C.; Melo, A.; Sheldon, P.; Snook, B.; Tuo, S.; Velkovska, J.; Arenton, M. W.; Balazs, M.; Boutle, S.; Conetti, S.; Cox, B.; Francis, B.; Goadhouse, S.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Lin, C.; Neu, C.; Wood, J.; Yohay, R.; Gollapinni, S.; Harr, R.; Karchin, P. E.; Kottachchi Kankanamge Don, C.; Lamichhane, P.; Mattson, M.; Milstène, C.; Sakharov, A.; Anderson, M.; Bachtis, M.; Belknap, D.; Bellinger, J. N.; Bernardini, J.; Carlsmith, D.; Cepeda, M.; Dasu, S.; Efron, J.; Friis, E.; Gray, L.; Grogg, K. S.; Grothe, M.; Hall-Wilton, R.; Herndon, M.; Hervé, A.; Klabbers, P.; Klukas, J.; Lanaro, A.; Lazaridis, C.; Leonard, J.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Pierro, G. A.; Ross, I.; Savin, A.; Smith, W. H.; Swanson, J.

    2012-05-01

    A search for quark compositeness using dijet angular distributions from pp collisions at √{s} = 7 TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 fb-1, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95 % confidence level.

  11. Search for quark compositeness in dijet angular distributions from pp collisions at sqrt(s) = 7 TeV

    SciTech Connect

    Chatrchyan, Serguei; et al.

    2012-05-01

    A search for quark compositeness using dijet angular distributions from pp collisions at sqrt(s) = 7 TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 inverse femtobarns, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95% confidence level.

  12. A feasibility study of altered spatial distribution of losses induced by eddy currents in body composition analysis

    PubMed Central

    2010-01-01

    Background Tomographic imaging has revealed that the body mass index does not give a reliable state of overall fitness. However, high measurement costs make the tomographic imaging unsuitable for large scale studies or repeated individual use. This paper reports an experimental investigation of a new electromagnetic method and its feasibility for assessing body composition. The method is called body electrical loss analysis (BELA). Methods The BELA method uses a high-Q parallel resonant circuit to produce a time-varying magnetic field. The Q of the resonator changes when the sample is placed in its coil. This is caused by induced eddy currents in the sample. The new idea in the BELA method is the altered spatial distribution of the electrical losses generated by these currents. The distribution of losses is varied using different excitation frequencies. The feasibility of the method was tested using simplified phantoms. Two of these phantoms were rough estimations of human torso. One had fat in the middle of its volume and saline solution in the outer shell volume. The other had reversed conductivity distributions. The phantoms were placed in the resonator and the change in the losses was measured. Five different excitation frequencies from 100 kHz to 200 kHz were used. Results The rate of loss as a function of frequency was observed to be approximately three times larger for a phantom with fat in the middle of its volume than for one with fat in its outer shell volume. Conclusions At higher frequencies the major signal contribution can be shifted toward outer shell volume. This enables probing the conductivity distribution of the subject by weighting outer structural components. The authors expect that the loss changing rate over frequency can be a potential index for body composition analysis. PMID:21047441

  13. Bacterial Composition in a Metropolitan Drinking Water Distribution System Utilizing Different Source Waters

    EPA Science Inventory

    The microbial community structure was investigated from bulk phase water samples of multiple collection sites from two service areas within the Cincinnati drinking water distribution system (DWDS). Each area is associated with a different primary source of water (i.e., groundwat...

  14. ALUMINUM-CONTAINING SCALES IN WATER DISTRIBUTION SYSTEMS: PREVALENCE AND COMPOSITION

    EPA Science Inventory

    Aluminum (Al) deposits in distribution systems can have important detrimental effects on tap water quality because they can increase turbidity and interfere with disinfection, and they can increase energy loss during water transport. There is also the possibility that they have ...

  15. Bacterial Composition of Biofilms Collected From Two Service Areas in a Metropolitan Drinking Water Distribution System

    EPA Science Inventory

    The development and succession of bacteria were examined by 16S rRNA gene clone libraries generated from various biofilms within a metropolitan water distribution system. Biofilms were obtained from off-line devices using polycarbonate coupons from annular reactors incubated for ...

  16. Fatigue behavior and life prediction of a SiC/Ti-24Al-11Nb composite under isothermal conditions. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Bartolotta, Paul A.

    1991-01-01

    Metal Matrix Composites (MMC) and Intermetallic Matrix Composites (IMC) were identified as potential material candidates for advanced aerospace applications. They are especially attractive for high temperature applications which require a low density material that maintains its structural integrity at elevated temperatures. High temperature fatigue resistance plays an important role in determining the structural integrity of the material. This study attempts to examine the relevance of test techniques, failure criterion, and life prediction as they pertain to an IMC material, specifically, unidirectional SiC fiber reinforced titanium aluminide. A series of strain and load controlled fatigue tests were conducted on unidirectional SiC/Ti-24Al-11Nb composite at 425 and 815 C. Several damage mechanism regimes were identified by using a strain-based representation of the data, Talreja's fatigue life diagram concept. Results of these tests were then used to address issues of test control modes, definition of failure, and testing techniques. Finally, a strain-based life prediction method was proposed for an IMC under tensile cyclic loadings at elevated temperatures.

  17. [Dietary modification of body composition and fat tissue distribution in obese menopausal women].

    PubMed

    Friedrich, Mariola

    2007-01-01

    The study was aimed at determining effects of health-oriented education in nutrition and the resultant changes in diet composition and dietary habits on body weight, values of BMI, WHR, and WHtR, body composition, and location of the lost fat tissue in obese menopausal women. The research was carried out in 2004-2007 and involved 146 women aged 46-60 years, with BMI >30.0 and >40.0, i.e., indicative of second and third degree obesity. The subjects were exposed to a 4-month-long education in nutrition. The classes were held once a week for 90 minutes, for groups of 20-22. The curriculum covered, i.a., information on the physiological role, sources of, and demand for basic nutrients, vitamins, macro- and micro-elements, and water; diet-based prevention of coronary diseases, insulin-independent diabetes, and diet-dependent cancer; and numerous other topics related to physiology and dietetics. The 4 months of health-oriented education in nutrition was found to be important in shaping dietary habits of the subjects, which was manifested as: development of a dietary pattern involving the magnitude and timings of meals, increased consumption of protein, whole-grain cereal products, pulses, fruits, and vegetables, accompanied by reduction in the consumption of sausages, sugar, and sweets. As a result, the women involved experiences a slow, but consistent body weight reduction as well as a decrease in the values of the body mass indices. Significant changes in body composition were found; the changes involved not only a significant reduction in fat per cent and increased percentage of fat-free body mass and water in the total body weight, but also an absolute reduction of body fat content, the absolute contents of fat-free mass and water remaining unchanged. PMID:18540320

  18. Composites

    NASA Astrophysics Data System (ADS)

    Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-Nędza, A.; Mackiewicz, S.; Dutkiewicz, J.

    2014-11-01

    It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

  19. Biophysical transport model suggests climate variability determines distribution of Walleye Pollock early life stages in the eastern Bering Sea through effects on spawning

    NASA Astrophysics Data System (ADS)

    Petrik, Colleen M.; Duffy-Anderson, Janet T.; Mueter, Franz; Hedstrom, Katherine; Curchitser, Enrique N.

    2015-11-01

    The eastern Bering Sea recently experienced an anomalously warm period followed by an anomalously cold period. These periods varied with respect to sea ice extent, water temperature, wind patterns, and ocean circulation. The distributions of Walleye Pollock early life stages also differed between periods, with larval stages found further eastward on the shelf in warm years. Statistical analyses indicated that these spatial distributions were more closely related to temperature than to other covariates, though a mechanism has not been identified. The objective of this study was to determine if variable transport could be driving the observed differences in pollock distributions. An individual-based model of pollock early life stages was developed by coupling a hydrodynamic model to a particle-tracking model with biology and behavior. Simulation experiments were performed with the model to investigate the effects of wind on transport, ice presence on time of spawning, and water temperature on location of spawning. This modeling approach benefited from the ability to individually test mechanisms to quantitatively assess the impact of each on the distribution of pollock. Neither interannual variability in advection nor advances or delays in spawning time could adequately represent the observed differences in distribution between warm and cold years. Changes to spawning areas, particularly spatial contractions of spawning areas in cold years, resulted in modeled distributions that were most similar to observations. The location of spawning pollock in reference to cross-shelf circulation patterns is important in determining the distribution of eggs and larvae, warranting further study on the relationship between spawning adults and the physical environment. The different distributions of pollock early life stages between warm and cold years may ultimately affect recruitment by influencing the spatial overlap of pollock juveniles with prey and predators.

  20. Distribution of stable isotopes in arid storms . I. Relation between the distribution of isotopic composition in rainfall and in the consequent runoff

    NASA Astrophysics Data System (ADS)

    Adar, E. M.; Dody, A.; Geyh, M. A.; Yair, A.; Yakirevich, A.; Issar, A. S.

    Temporal distributions of the isotopic composition in arid rain storms and in the associated runoff were investigated in a small arid rocky basin in Israel. Customized rain and runoff samplers provided sequential water samples hermetically sealed in high-density PVC bags. In several storms where the runoff was isotopically depleted, compared with the rainfall, the difference could not be explained by fractionation effects occurring during overland flow. A water-balance study relating the runoff discharge to rainfall over a rocky watershed showed that the entire discharge is produced by a very small segment (1-2mm) of the rain storm. The major objective, therefore, was to provide quantitative relations between segments of rainfall (rain showers and rain spells) and runoff. The time distribution of the composition of stable isotopes (oxygen and hydrogen) was used to quantify the correlation between the rain spell's amount and the consequent runoff. The aim of this work was to (a) utilize the dynamic variations in the isotopic composition in rainfall and runoff and model the magnitude of surface-storage capacity associated with runoff processes of overland flow, and (b) characterize the isotopic composition of the percolating water with respect to the isotopic distribution in rainfall and runoff events. The conceptual model postulates an isotopic mixing of overland flow with water within the depression storage. A transport model was then formulated in order to estimate the physical watershed parameters that control the development of overland flow from a certain rainfall period. Part I (this paper) presents the results and the assessment of the relative depression storage obtained from oxygen-18 and deuterium analyses that lead to the physical and mathematical formulation of a double-component model of kinematic-wave flow and transport, which is presented in Part II (accompanying paper). Résumé Les variations temporelles, en zone aride, de la composition isotopique des précipitations et du ruissellement associé ont étéétudiées dans un petit bassin rocheux aride en Israël. Des préleveurs spécialement adaptés pour la pluie et le ruissellement ont fourni des échantillons séquentiels dans des sacs en PVC haute densité hermétiquement fermés. Au cours de plusieurs épisodes pluvieux où le ruissellement était isotopiquement appauvri par rapport à la pluie, la différence ne pouvait pas être expliquée par des effets de fractionnement intervenant au cours de l'écoulement en surface. Un bilan hydrologique rapportant l'écoulement de surface à la pluie sur un bassin versant rocheux montre que l'écoulement dans sa totalité est alimenté par une très petite partie (1-2mm) de l'averse. C'est pourquoi l'objectif essentiel a été de rechercher des relations quantitatives entre des parties de la pluie (averses et épisodes pluvieux) et le ruissellement. La répartition temporelle de la composition en isotopes stables (oxygène et hydrogène) a été utilisée pour quantifier la corrélation entre la hauteur tombée pendant l'épisode pluvieux et le ruissellement produit. Le but de ce travail était (a) d'utiliser les variations dynamiques de la composition isotopique dans la pluie et dans le ruissellement pour modéliser l'ordre de grandeur de la capacité de stockage de surface associée aux processus de ruissellement de l'écoulement de surface, et (a) de caractériser la composition isotopique de l'eau d'infiltration par rapport à la variation isotopique observée dans les pluies et dans les écoulements correspondants. Resumen La distribución temporal de la composición isotópica de las tormentas en zonas áridas y la correspondiente escorrentía se analizó en una pequeña cuenca rocosa en Israel. Los medidores de lluvia y escorrentía proporcionaron muestras de agua secuenciales, selladas herméticamente en bolsas de PVC de alta densidad. En muchas tormentas en las que la escorrentía tenía una composición isotópica distinta de la lluvia, la diferencia no podía explicarse por efectos de fraccionamiento isotópico. Un balance de agua relacionando los términos de lluvia y escorrentía en una cuenca rocosa mostraron que la totalidad de la descarga se produce por un segmento muy pequeño de la lluvia (1-2mm). El principal objetivo, por tanto, era proporcionar relaciones cuantitativas entre los distintos segmentos de la lluvia (tormentas aisladas y periodos lluviosos) y la escorrentía, para lo cual se utilizó la distribución temporal de la composición de los isótopos estables (oxígeno e hidrógeno). El objetivo del estudio era (a) utilizar las variaciones dinámicas en la composición isotópica de lluvia y escorrentía para modelar la magnitud de la capacidad de almacenamiento en superficie asociada con los procesos de escorrentía, y (b) caracterizar la composición isotópica del agua de percolación respecto a la correspondientes a lluvia y escorrentía.

  1. Simplified Shear Solution for Determination of the Shear Stress Distribution in a Composite Panel from the Applied Shear Resultant

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.; Collier, Craig S.

    2008-01-01

    The simplified shear solution method is presented for approximating the through-thickness shear stress distribution within a composite laminate or panel based on laminated beam theory. The method does not consider the solution of a particular boundary value problem; rather it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply level stresses can be efficiently determined from global load resultants (as determined, for instance, by finite element analysis) at a given location in a structure and used to evaluate the margin of safety on a ply by ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. Comparisons to existing theories are made for a variety of laminates, and design examples are provided illustrating the use of the method for determining through-thickness shear stress margins in several types of composite panels and in the context of a finite element structural analysis.

  2. The Impact of Oil Consumption Mechanisms on Diesel Exhaust Particle Size Distributions and Detailed Exhaust Chemical Composition

    SciTech Connect

    Stetter, J; Forster, N; Ghandhi, J; Foster, D

    2003-08-24

    Detailed exhaust emission data have been taken from a Cummins N-14 single cylinder research engine in which the oil consumption was varied by different engine modifications. Low sulfur fuel was used, and oil consumption was varied by modifying the intake valve stem seals, the exhaust valve stem seals, the oil control ring and combinations of these modifications. Detailed measurements of exhaust gas particle size distributions and chemical composition were made for the various oil consumption configurations for a range of engine loads and speeds. The particulate mass was measured with TEOM and traditional gravimetric filter methods. Filter data for EC/OC, sulfates and trace metals have been taken and analyzed. The trace metals in the particulate mass serve as the basis for assessing oil consumption at the different operating conditions. The data indicate that the oil consumption for the steady state testing done here was approximately an order of magnitude below oil consumption values cited in the literature. We did measure changes in the details of the chemical composition of the particulate for the different engine operating conditions, but it did not correlate with changes in the oil consumption. Furthermore, the data indicate that the particle size distribution is not strongly impacted by low level oil consumption variations observed in this work.

  3. Stress distribution in a transversely loaded cross-shaped single fiber SCS-6/Ti-6Al-4V composite

    SciTech Connect

    Warrier, S.G.; Gundel, D.B.; Majumdar, B.S.; Miracle, D.B.

    1996-01-15

    In most structural applications utilizing fiber reinforced metal matrix composites (MMCs), the mechanical response normal to the fiber direction has to be considered. The transverse response is very sensitive to the interface bond strength, which has commonly been determined by testing straight-sided 90{degree} specimens and interpreting debond initiation from the knee in the stress-strain curve as well as from a sudden drop in the Poisson`s ratio. In an attempt to modify the debond initiation site to an internal location free of uncharacteristic states of stress, a cross-shaped specimen has been developed. Experiments conducted by Gundel et al. indicated that this geometry was successful in obtaining the appropriate crack initiation site. In the present study, finite element analysis (FEA) was done on the cross-shaped specimen to obtain the stress distribution in the composite under transverse loading, in an effort to corroborate the success of this geometry in determining the true transverse response of the composite.

  4. Composition and Tissue-Specific Distribution of Stilbenoids in Grape Canes Are Affected by Downy Mildew Pressure in the Vineyard.

    PubMed

    Houillé, Benjamin; Besseau, Sébastien; Delanoue, Guillaume; Oudin, Audrey; Papon, Nicolas; Clastre, Marc; Simkin, Andrew John; Guérin, Laurence; Courdavault, Vincent; Giglioli-Guivarc'h, Nathalie; Lanoue, Arnaud

    2015-09-30

    Grape canes are byproducts of viticulture containing valuable bioactive stilbenoids including monomers and oligomers of E-resveratrol. Although effective contents in stilbenoids are known to be highly variable, the determining factors influencing this composition remain poorly understood. As stilbenoids are locally induced defense compounds in response to phytopathogens, this study assessed the impact of downy mildew infection during the growing season on the stilbenoid composition of winter-harvested grape canes. The spatial distribution between pith, conducting tissues, and cortex of E-piceatannol, E-resveratrol, E-ε-viniferin, ampelopsin A, E-miyabenol C, Z/E-vitisin B, hopeaphenol, and isohopeaphenol in grape canes from infected vineyards was strongly altered. In conducting tissues, representing the main site of stilbenoid accumulation, E-ε-viniferin content was higher and E-resveratrol content was lower. These findings suppose that the health status in vineyards could modify the composition of stilbenoids in winter-harvested grape canes and subsequently the potential biological properties of the valuable extracts. PMID:26373576

  5. Lifelong maintenance of composition, function and cellular/subcellular distribution of proteasomes in human liver.

    PubMed

    Bellavista, Elena; Martucci, Morena; Vasuri, Francesco; Santoro, Aurelia; Mishto, Michele; Kloss, Alexander; Capizzi, Elisa; Degiovanni, Alessio; Lanzarini, Catia; Remondini, Daniel; Dazzi, Alessandro; Pellegrini, Sara; Cescon, Matteo; Capri, Miriam; Salvioli, Stefano; D'Errico-Grigioni, Antonia; Dahlmann, Burkhardt; Grazi, Gian Luca; Franceschi, Claudio

    2014-01-01

    Owing to organ shortage, livers from old donors are increasingly used for transplantation. The function and duration of such transplanted livers are apparently comparable to those from young donors, suggesting that, despite some morphological and structural age-related changes, no major functional changes do occur in liver with age. We tested this hypothesis by performing a comprehensive study on proteasomes, major cell organelles responsible for proteostasis, in liver biopsies from heart-beating donors. Oxidized and poly-ubiquitin conjugated proteins did not accumulate with age and the three major proteasome proteolytic activities were similar in livers from young and old donors. Analysis of proteasomes composition showed an age-related increased of β5i/α4 ratio, suggesting a shift toward proteasomes containing inducible subunits and a decreased content of PA28α subunit, mainly in the cytosol of hepatocytes. Thus our data suggest that, proteasomes activity is well preserved in livers from aged donors, concomitantly with subtle changes in proteasome subunit composition which might reflect the occurrence of a functional remodelling to maintain an efficient proteostasis. Gender differences are emerging and they deserve further investigations owing to the different aging trajectories between men and women. Finally, our data support the safe use of livers from old donors for transplantation. PMID:25265087

  6. Probing the Structure, Composition, and Spatial Distribution of Ligands on Gold Nanorods.

    PubMed

    Hore, Michael J A; Ye, Xingchen; Ford, Jamie; Gao, Yuzhi; Fei, Jiayang; Wu, Qiong; Rowan, Stuart J; Composto, Russell J; Murray, Christopher B; Hammouda, Boualem

    2015-09-01

    The structure and size of ligands attached to the surfaces of gold nanorods, such as adsorbed surfactants or grafted polymers, are important considerations that facilitate the use of such nanoparticles in the human body, in advanced materials for energy harvesting, or in devices for single molecule detection. Here, we report small-angle neutron scattering (SANS) measurements from surfactant or poly(ethylene glycol) (PEG) coated gold nanorods in solution, which quantitatively determine the location, structure, and composition of these surface layers. In addition, by synthesizing gold nanorods using seed crystals which are coated with deuterated cetyltrimethylammonium bromide (dCTAB), we are able to exploit the isotopic sensitivity of SANS to study, for the first time, the retention of surfactant from the seed crystals to the final gold nanorod product, finding that very little exchange of the deuterated with hydrogenated surfactant occurs. Finally, we demonstrate that, when Au NRs are PEGylated using standard techniques, the surfactant bilayer remains intact, and while mass spectrometry detects the presence of both surfactant and PEG, the composition as measured from SANS is predominantly that of the surfactant. These measurements not only provide new insight into the synthesis and functionalization of gold nanorods but provide a quantitative picture of the structure of grafted polymer and surfactant layers on gold nanorod surfaces which has implications for the fabrication of plasmonic and biomedical materials. PMID:26292087

  7. Chemical composition of essential oils of Litsea cubeba harvested from its distribution areas in China.

    PubMed

    Si, Linlin; Chen, Yicun; Han, Xiaojiao; Zhan, Zhiyong; Tian, Shengping; Cui, Qinqin; Wang, Yangdong

    2012-01-01

    Litsea cubeba (Lour.) Pers. is a promising industrial crop with fruits rich in essential oils. The chemical composition of essential oils of L. cubeba (EOLC) were determined for fruits harvested from eight regions in China. The overall essential oil content, obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), ranged from 3.04% to 4.56%. In total, 59 compounds were identified, the dominant components being monoterpenes (94.4-98.4%), represented mainly by neral and geranial (78.7-87.4%). D-Limonene was unexpectedly a lesser constituent (0.7-5.3%) in fruits, which differed from previous reports (6.0-14.6%). Several components were only detected in certain regions and compounds such as o-cymene and eremophilene have never before been reported in EOLC. These results demonstrate significant regional variation in the chemical composition of EOLC. This investigation provides important information with regard to the bioactivity, breeding work and industrial applications of L. cubeba. PMID:22683894

  8. Salp distribution and size composition in the Atlantic sector of the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Kawaguchi, S.; Siegel, V.; Litvinov, F.; Loeb, V.; Watkins, J.

    2004-06-01

    Salp abundance and length frequency were measured during the large-scale CCAMLR 2000 Survey conducted in the Atlantic Sector of the Southern Ocean in the 1999/2000 season. Results from regional surveys around Elephant Island in 1994/95 and 1996/97 seasons also were examined. During the CCAMLR 2000 Survey, salp abundance was higher in the Antarctic Peninsula and South Sandwich Island areas than in the central Scotia Sea. The probable reason for this pattern is a negative relationship with phytoplankton abundance; the central Scotia Sea having greater phytoplankton concentrations than required for optimal salp filter-feeding performance. Cluster analysis of salp size composition resulted in three cluster groups for each of the three surveys. Clusters comprising large salps occurred in warmer waters in all three surveys. The size composition of the salp populations suggests that the timing of intense asexual reproductive budding was earlier in warmer waters. As surface water temperatures generally decrease from north to south, and increase from spring to summer, the general spatio-temporal pattern of asexual reproduction by budding is likely to proceed from north to south as the summer season progresses.

  9. Carbon, nitrogen and sulfur in lunar fines 15012 and 15013 - Abundances, distributions and isotopic compositions

    NASA Technical Reports Server (NTRS)

    Chang, S.; Lawless, J.; Romiez, M.; Kaplan, I. R.; Petrowski, C.; Sakai, H.; Smith, J. W.

    1974-01-01

    Lunar fines 15012,16 and 15013,3 were analyzed by stepwise pyrolysis and acid hydrolysis as well as complete combustion in oxygen to determine carbon, nitrogen and sulfur. In addition, hydrogen was analysed during pyrolysis as well as during hydrolysis. By comparison of the distribution frequencies of C, N, S, H2 and Fe with He-4, considered to have arisen from solar wind contribution, it is concluded that nitrogen and hydrogen have largely a solar origin. Carbon has a significant solar contribution, and metallic iron may have resulted from solar wind interaction with ferrous minerals on the lunar surface. Sulfur probably has a predominantly lunar origin. There is no direct evidence for meteorotic contribution to these samples. Solar wind interaction also has a marked effect on the stable isotope distribution of C-13/C-12, N-15/N-14, and S-34/S-32. In all cases, the heavy isotope was most enriched in the smallest grain-size fraction.

  10. Vertical distribution and isotopic composition of living planktonic foraminifera in the western North Atlantic

    SciTech Connect

    Fairbanks, R.G.; Wiebe, P.H.; Be, A.W.H.

    1980-01-04

    Thirteen species of planktonic foraminifera collected with vertically stratified zooplankton tows in the slope water, Gulf Stream cold core ring, and northern Sargasso Sea show significant differences in their vertical distributions in the upper 200 meters of these different hydrographic regimes. Gulf Stream cold core rings may be responsible for a southern displacement of the faunal boundary associated with the Gulf Stream when reconstructed from the deep-sea sediment record. Oxygen isotope analyses of seven species reveal that nonspinose species (algal symbiont-barren) apparently calcify in oxygen isotope equilibrium, whereas spinose species usually calcify out of oxygen isotope equilibrium by approximately -0.3 to -0.4 per mil in delta/sup 18/O values. The isotope data indicate that foraminifera shells calcify in depth zones that are significantly narrower than the overall vertical distribution of a species would imply.

  11. Composition, enantiomeric distribution, and antimicrobial activity of Tanacetum argenteum subsp. flabellifolium essential oil.

    PubMed

    Tabanca, Nurhayat; Demirci, Fatih; Demirci, Betül; Wedge, David E; Baser, K Hüsnü Can

    2007-12-21

    Tanacetum argenteum (Lam.) Willd. subsp. flabellifolium (Boiss. & Heldr.) Grierson of Asteraceae is an endemic species in Turkey. Hydrodistillation of aerial parts using a Clevenger apparatus yielded an essential oil, which was subsequently analyzed by gas chromatography-mass spectroscopy (GC-MS). alpha-Pinene (29%), (E)-sesquilavandulol (16%), and camphor (14%) were found as main constituents. Enantiomeric distribution of the monoterpenes alpha-pinene and camphor was determined on a fused silica Lipodex E capillary column using a multidimensional gas chromatography-mass spectroscopy (MDGC-MS) system, (-)-alpha-pinene (86%), (+)-alpha-pinene (14%), and (-)-camphor (100%) enantiomeric distributions were found in the oil. Furthermore, antimicrobial activity of the oil was carried out using a micro-dilution assay against human pathogenic bacteria and the yeast Candida albicans resulting in moderate inhibitory concentrations (MIC=125 microg/mL). PMID:17884324

  12. Alkane distribution and carbon isotope composition in fossil leaves: An interpretation of plant physiology in the geologic past

    NASA Astrophysics Data System (ADS)

    Graham, H. V.; Freeman, K. H.

    2014-12-01

    The relative chain-length distribution and carbon-isotope composition of n-alkanes extracted from sedimentary rocks are important geochemical tools for investigating past terrestrial ecosystems. Alkanes preserved in ancient sediments are assumed to be contemporaneous, derived from the same ecosystem, and integrated from the biomass present on the landscape at the time of deposition. Further, there is an underlying assumption that ancient plants exhibited the same metabolic and physiological responses to climate conditions that are observed for modern plants. Interpretations of alkane abundances and isotopic signatures are complicated by the strong influence of phylogenetic affiliation and ecological factors, such as canopy structure. A better understanding of how ecosystem and taxa influence alkane properties, including homologue abundance patterns and leaf-lipid carbon isotope fractionation would help strengthen paleoecological interpretations based on these widely employed plant biomarkers. In this study, we analyze the alkane chain-length distribution and carbon-isotope composition of phytoleim and alkanes (d13Cleaf and d13Clipid) extracted from a selection of Cretaceous and Paleocene fossil leaves from the Guaduas and Cerrejon Formations of Colombia. These data were compared with data for the same families in a modern analogue biome. Photosynthetic and biosynthetic fractionation (∆leaf and elipid) values determined from the fossil material indicate carbon metabolism patterns were similar to modern plants. Fossil data were incorporated in a biomass-weighted mixing model to represent the expected lipid complement of sediment arising from this ecosystem and compared with alkane measurements from the rock matrix. Modeled and observed isotopic and abundance patterns match well for alkane homologs most abundant in plants (i.e., n-C27 to n-C33). The model illustrates the importance of understanding biases in litter flux and taphonomic pressures inherent in the fossil lipid record, and it highlights the influence of community composition and forest structure on sedimentary lipids.

  13. Distribution, composition and seasonality of aquatic birds in the Nhecolândia sub-region of South Pantanal, Brazil.

    PubMed

    Donatelli, R J; Posso, S R; Toledo, M C B

    2014-11-01

    Despite remarkable significance of Pantanal for the conservation of aquatic birds, the status of their populations, the spatiotemporal patterns of distribution and habitat use and structure of communities are little known. Thus, we studied three aquatic environments (Negro river, bays and salines) from 2007 to 2009 in the Nhecolândia Pantanal to verify the distribution and composition of aquatic birds and also if there is significant seasonal influence on these aspects. We adopted the transect method (288 hours of sampling) and recorded 135 species (7.834 individuals). The Negro river showed the highest diversity, while the salines the lowest. The similarity of aquatic bird communities was higher between bays and salines, followed by Negro river and bays and lower between salines and Negro river. The equidistribution is more variable in the salines and more stable in the Negro river. The environments strongly differ from each other in aquatic bird composition in space (habitat use and distribution) and time (seasonal water fluctuations). The diversity of bird community in the dry season varies significantly in the salines, followed by the bays and more stable in the Negro river. The Negro river, regardless of large annual amplitude of flow, is more seasonally stable since its riparian vegetation is continuous (not isolated) and constant. These aspects provide better conditions to stay all year, contributing to decrease the seasonal nomadic tendencies of aquatic birds. Finally, all these data provide strong arguments to the preservation of all phytophysiognomies in the Nhecolândia sub- region of Pantanal, but with special attention to the salines widely used by many flocks of aquatic birds (mainly in the dry season) and migrant and/or rare species restricted to this habitat. PMID:25627594

  14. A preliminary analysis of lunar extra-mare basalts - Distribution, compositions, ages, volumes, and eruption styles

    NASA Technical Reports Server (NTRS)

    Whitford-Stark, J. L.

    1982-01-01

    Extra-mare basalts occupy 8.5% of the lunar basalt area and comprise 1% of the total mare basalt volume. They are preferentially located where the crust is thin and topographically low. In terms of age, eruption style, and composition they are as variable as the mare basalts. In some instances extrusion in extra-mare craters was preceded by floor-fracturing whereas in other cases it apparently was not. The volume of lava erupted may have been controlled more by the volume of magma produced than by hydrostatic effects. A minimum of nearly 1300 separate basalt eruptions is indicated; the true value could be nearer 30,000 separate eruptions.

  15. Composition and distribution of lipids in tissues of bogue (Boops boops).

    PubMed

    Kapoulas, V M; Miniadis-Meimaroglou, S

    1985-01-01

    Total lipids from liver, head, skin and muscle of Bogue were separately isolated and their composition was investigated by a combination of analytical determinations, and column and thin layer chromatography. The major components of the neutral lipid fractions from all tissues studied were triglycerides, followed by cholesterol. The triglyceride fraction of skin and head contains significant amounts of glyceryl ether analogs. Low contents of free fatty alcohols were also identified, decreasing in the order: head, muscle, skin and liver. The major components of all phospholipid fractions was phosphatidylcholine (viz. 36-59% of total phospholipids) followed by phosphatidylethanolamine (viz. 23-34% of total phospholipids). Low amounts of sphingomyelin and phosphatidylserine were also identified in all cases. All the tissues studied were found to contain plasmalogens, as well as glyceryl ether analogs in both, the depot fats and the phospholipid fractions. PMID:4050028

  16. Composition and fatty acid distribution of bovine milk phospholipids from processed milk products

    PubMed Central

    Gallier, Sophie; Gragson, Derek; Cabral, Charles; Jiménez-Flores, Rafael; Everett, David W.

    2014-01-01

    The aim of this work was to assess the accuracy of different extraction methods of phospholipids and to measure the effect that processing has on phospholipid composition. Four methods of extracting phospholipids from buttermilk powder were compared to optimize recovery of sphingomyelin. Using the optimal method, the phospholipid profile of four dairy products (raw milk, raw cream, homogenized and pasteurized milk, and buttermilk powder) was determined. A total lipid extraction by the Folch method followed by a solid-phase extraction using the Bitman method was the most efficient technique to recover milk sphingomyelin. Milk processing (churning, centrifuging, homogenization, spray-drying) affected the profile of milk phospholipids, leading to a loss of sphingomyelin and phosphatidylcholine after centrifugation for cream separation. We also observed a corresponding decrease in the saturation content of the raw cream phospholipids, and a loss of phosphatidylethanolamine after spray-drying to produce buttermilk powder. PMID:20828196

  17. Ecological composition and distribution of the diatoms from the Laguna Superior, Oaxaca, Mexico.

    PubMed

    Moreno-Ruiz, José Luis; Tapia-Garcia, Margarito; Licea, Sergio; Figueroa-Torres, María Guadalupe; Esquivel, Alfonso; Herrera-Galindo, Jorge Eduardo; González-Fernández, José Manuel; González-Macias, Maria Del Carmen

    2011-07-01

    A taxonomic study of diatoms was carried out in a tropical coastal lagoon. Material for this study consists of water samples obtained from February-March 1992 to November-December 2000. Qualitative and quantitative analyses showed the presence of 373 taxa of which the families Bacillariaceae (67 species) and Chaetocerotaceae (37 species) were the most abundant groups. The species Skeletonema costatum, Chaetoceros curvisetus, Coscinodiscus radiatus var. radiatus, Ditylum brightwellii, Thalassiosira eccentrica and Entomoneis alata were found associated with moderate water quality and forming blooms. In addition, a regional comparison between Mexico and South America of the identified species is given. For practical handling, indicative values obtained from their ecological composition are incorporated as well as a code of the floristic list. Achecklist of the species and their occurrence are given. PMID:22315822

  18. Top-down control of soil fungal community composition by a globally distributed keystone consumer.

    PubMed

    Crowther, Thomas W; Stanton, David W G; Thomas, Stephen M; A'Bear, A Donald; Hiscox, Jennifer; Jones, T Hefin; Vorísková, Jana; Baldrian, Petr; Boddy, Lynne

    2013-11-01

    The relative contribution of top-down and bottom-up processes regulating primary decomposers can influence the strength of the link between the soil animal community and ecosystem functioning. Although soil bacterial communities are regulated by bottom-up and top-down processes, the latter are considered to be less important in structuring the diversity and functioning of fungal-dominated ecosystems. Despite the huge diversity of mycophagous (fungal-feeding) soil fauna, and their potential to reverse the outcomes of competitive fungal interactions, top-down grazing effects have never been found to translate to community-level changes. We constructed soil mesocosms to investigate the potential of isopods grazing on cord-forming basidiomycete fungi to influence the community composition and functioning of a complex woodland soil microbial community. Using metagenomic sequencing we provide conclusive evidence of direct top-down control at the community scale in fungal-dominated woodland soil. By suppressing the dominant cord-forming basidiomycete fungi, isopods prevented the competitive exclusion of surrounding litter fungi, increasing diversity in a community containing several hundred fungal species. This isopod-induced modification of community composition drove a shift in the soil enzyme profile, and led to a restructuring of the wider mycophagous invertebrate community. We highlight characteristics of different soil ecosystems that will give rise to such top-down control. Given the ubiquity of isopods and basidiomycete fungi in temperate and boreal woodland ecosystems, such top-down community control could be of widespread significance for global carbon and nutrient cycling. PMID:24400503

  19. Distribution of aquatic macrophytes in contrasting river systems: a critique of compositional-based assessment of water quality.

    TOXLINE Toxicology Bibliographic Information

    Demars BO; Edwards AC

    2009-01-01

    A brief summary of the historical developments relating to plant distribution and aquatic macrophyte-nutrient indices provided a means of assessing the general context and validity of previous assumptions. This has particular current relevance because of the prominent use of bioindicators for defining nutrient enrichment. A survey of 161 sites distributed across two broadly contrasting groups of rivers (circum-neutral versus alkaline) recorded 110 species of aquatic macrophytes and these have been statistically analyzed to (i) rank and separate the individual effects of local environmental conditions and spatial isolation on species distribution in the two contrasting groups of sites; (ii) calculate a macrophyte index based on plant cover and species indicator values (Mean Trophic Rank, MTR); and finally (iii) investigate the implications for biomonitoring. Chemical, physical and hydrological site attributes together with spatial isolation, each explained a significant and at least partially independent influence over plant species distribution. It was extremely difficult, however, to separate the single effects of different site attributes on plant distribution. While some plant species are more restricted to certain environmental conditions, many appeared indifferent to the range of those being tested. The role played by nutrients (nitrogen (N) and phosphorus (P)) were either mostly indistinguishable from other site attributes (e.g., nitrate from conductivity) or subordinate (e.g., soluble reactive phosphorus, ammonium). It is therefore very unlikely that macrophyte species composition could provide a reliable bioindicator of the surrounding nutrient (N, P) status. The calculation of the plant index illustrated this unreliability by showing that strong correlations existed with many environmental variables, not just inorganic N and P.

  20. Distribution of aquatic macrophytes in contrasting river systems: a critique of compositional-based assessment of water quality.

    PubMed

    Demars, Benoît O L; Edwards, Anthony C

    2009-01-01

    A brief summary of the historical developments relating to plant distribution and aquatic macrophyte-nutrient indices provided a means of assessing the general context and validity of previous assumptions. This has particular current relevance because of the prominent use of bioindicators for defining nutrient enrichment. A survey of 161 sites distributed across two broadly contrasting groups of rivers (circum-neutral versus alkaline) recorded 110 species of aquatic macrophytes and these have been statistically analyzed to (i) rank and separate the individual effects of local environmental conditions and spatial isolation on species distribution in the two contrasting groups of sites; (ii) calculate a macrophyte index based on plant cover and species indicator values (Mean Trophic Rank, MTR); and finally (iii) investigate the implications for biomonitoring. Chemical, physical and hydrological site attributes together with spatial isolation, each explained a significant and at least partially independent influence over plant species distribution. It was extremely difficult, however, to separate the single effects of different site attributes on plant distribution. While some plant species are more restricted to certain environmental conditions, many appeared indifferent to the range of those being tested. The role played by nutrients (nitrogen (N) and phosphorus (P)) were either mostly indistinguishable from other site attributes (e.g., nitrate from conductivity) or subordinate (e.g., soluble reactive phosphorus, ammonium). It is therefore very unlikely that macrophyte species composition could provide a reliable bioindicator of the surrounding nutrient (N, P) status. The calculation of the plant index illustrated this unreliability by showing that strong correlations existed with many environmental variables, not just inorganic N and P. PMID:18977514

  1. Composition, distribution, and characterization of polycyclic aromatic hydrocarbons in soil in Linfen, China

    SciTech Connect

    Fu, S.; Cheng, H.X.; Liu, Y.H.; Xia, X.J.; Xu, X.B.

    2009-02-15

    A total of 10 surface soil samples representing the entire area of Linfen City were collected and analyzed for the presence of 16 polycyclic aromatic hydrocarbons. The total polycyclic aromatic hydrocarbon concentration ranged from 1.1 to 63.7 {mu} g g{sup -1}. Analysis of the sources of contamination revealed that polycyclic aromatic hydrocarbons in the soil were derived from combustion sources. Specifically, the primary source of polycyclic aromatic hydrocarbons was coal combustion, but the samples were also effected to varying degrees by traffic emissions. Furthermore, increased levels of contamination were observed in northeast Linfen due to the distribution of industrial plants.

  2. Mesozooplankton composition, biomass and vertical distribution, and copepod production in the stratified central north sea

    NASA Astrophysics Data System (ADS)

    Fransz, H. G.; Miquel, J. C.; Gonzalez, S. R.

    During three cruises to the Oyster Ground area in the central North Sea in 1981 the animal plankton was sampled at different depths by oblique hauls with a net and in 30 litre bottles. Copepods dominated, but echinopluteus larvae were equally numerous in July. Hydromedusae were the most abundant carnivores. Mean total biomass ADW estimates of herbivores amounted to 1.7, 5.8, and 2.9 g·m -2 in May, July and September, respectively, including 1.3, 2.3, and 1.5 g·m -2 of copepods. The carnivore biomass was 0.3 g·m -2 in May, 0.6 in July, and 0.8 in September. The vertical distribution of calanoid copepods followed the distribution of chlorophyll rather than particulate carbon. The copepod carbon production, calculated from biomass figures and literature growth parameters and extrapolated for the period May to October, amounted to at most 9 g·m -2. This does not exceed comparable values found for the isothermal Southern Bight of the North Sea. A positive influence of thermal stratification on the ratio of copepod production and primary production was not found.

  3. Strength distribution and size effects for the fracture of fibrous composite materials

    SciTech Connect

    Phoenix, S.L.; Beyerlein, I.J.

    1997-10-01

    Random network models have recently been developed in the physics literature to explain the strength and size effect in heterogeneous materials. Applications have included the breakdown and brittle fracture. Unfortunately, conventional scaling approaches of statistical mechanics have yielded incorrect predictions, and new approaches have been proposed which build on field enhancement occurring near the tips of critical, random clusters together with the statistical theory of extremes. New distributions and size scalings for strength have been proposed and supported through Monte Carlo simulation. Here we consider an idealized, one-dimensional model for the failure of such networks where elements of constant strength may be initially present or absent at random. Our idealized rule for local stress redistribution near breaks reflects features we find in a discrete mechanics model that has limiting forms consistent with continuum theories for cracks. We obtain rigorous asymptotic results for the strength distribution and size effect with constants and exponents that are known. The validity of various analytical approximations in the literature is then discussed.

  4. Mass size distributions and size resolved chemical composition of fine particulate matter at the Pittsburgh supersite

    NASA Astrophysics Data System (ADS)

    Cabada, Juan C.; Rees, Sarah; Takahama, Satoshi; Khlystov, Andrey; Pandis, Spyros N.; Davidson, Cliff I.; Robinson, Allen L.

    Size-resolved aerosol mass and chemical composition were measured during the Pittsburgh Air Quality Study. Daily samples were collected for 12 months from July 2001 to June 2002. Micro-orifice uniform deposit impactors (MOUDIs) were used to collect aerosol samples of fine particulate matter smaller than 10 μm. Measurements of PM 0.056, PM 0.10, PM 0.18, PM 0.32, PM 0.56, PM 1.0, PM 1.8 and PM 2.5 with the MOUDI are available for the full study period. Seasonal variations in the concentrations are observed for all size cuts. Higher concentrations are observed during the summer and lower during the winter. Comparison between the PM 2.5 measurements by the MOUDI and other integrated PM samplers reveals good agreement. Good correlation is observed for PM 10 between the MOUDI and an integrated sampler but the MOUDI underestimates PM 10 by 20%. Bouncing of particles from higher stages of the MOUDI (>PM 2.5) is not a major problem because of the low concentrations of coarse particles in the area. The main cause of coarse particle losses appears to be losses to the wall of the MOUDI. Samples were collected on aluminum foils for analysis of carbonaceous material and on Teflon filters for analysis of particle mass and inorganic anions and cations. Daily samples were analyzed during the summer (July 2001) and the winter intensives (January 2002). During the summer around 50% of the organic material is lost from the aluminum foils as compared to a filter-based sampler. These losses are due to volatilization and bounce-off from the MOUDI stages. High nitrate losses from the MOUDI are also observed during the summer (above 70%). Good agreement between the gravimetrically determined mass and the sum of the masses of the individual compounds is obtained, if the lost mass from organics and the aerosol water content are included for the summer. For the winter no significant losses of material are detected and there exists reasonable agreement between the gravimetrical mass and the sum of the concentrations of the individual compounds. Ultrafine particles (below 100 nm) account on average, for < 5% of the PM 2.5 mass, and show different composition for the summer and the winter. During the summer the ultrafine mass is 50% carbonaceous material (organic material and elemental carbon) and 50% inorganic (mainly sulfate and ammonium); during the winter these percentages are 70% and 30%, respectively.

  5. Distribution, species composition and relative abundances of sandflies in North Waziristan Agency, Pakistan.

    PubMed

    Ali, N; Ullah, A; Wahid, S; Khisroon, M; Rasheed, S B

    2016-03-01

    This study was conducted to investigate the diversity of sandflies (Psychodidae: Phlebotominae) and the incidence of leishmaniasis in three villages of North Waziristan Agency, Pakistan. Sandflies were sampled monthly during 2012, at dusk and dawn, in selected indoor habitats including both bedrooms and animal sheds using a knock-down spray catch method. A total of 3687 sandflies were collected, including 1444 individuals in Drezanda, 1193 in Damdil and 1050 in Dattakhel. This study revealed 14 species of two genera, Phlebotomus (Phlebotomus sergenti, Phlebotomus papatasi, Phlebotomus caucasicus, Phlebotomus kazeruni, Phlebotomus alexandri and Phlebotomus salehi) and Sergentomyia (Sergentomyia dentate, Sergentomyia baghdadis, Sergentomyia babu, Sergentomyia theodori, Sergentomyia sumbarica, Sergentomyia dreyfussitur kestanica, Sergentomyia hogsoni pawlowskyi and Sergentomyia fallax afghanica) (both: Diptera: Psychodidae). Phlebotomus sergenti was the most abundant species (42.1%), followed by S. dentata (17.7%) and S. baghdadis (17.4%). The number of males collected represented about twice that of female flies, and the maximum number was collected in July, followed by August. The determination of the species composition of sandfly populations, seasonal variations, relative abundances and estimations of infection in the vector population may provide information about the dynamics of leishmaniasis transmission that is useful in planning vector control activities. PMID:26582763

  6. Composition and cation-vacancy distribution of cation-deficient {Mn}/{Fe} spinel oxides

    NASA Astrophysics Data System (ADS)

    Mateos, J. M. Jimenez; Jones, W.; Morales, J.; Tirado, J. L.

    1991-08-01

    Chemical composition and vacancy ditribution are studied in cation-deficient {Mn}/{Fe} spinel oxides of general formula Fe 3- xMn xO 4+ y prepared by the thermal decomposition of mixed carbonates. An oxygen/metal ratio in the 1.5-1.6 range is found for samples obtained at 400°C in an air atmosphere. In addition, a significant content of Mn(IV) ions can be derived from chemical and XRD data. The Mössbauer data of these samples reveal the effects of small particle size as well as isolating effects of the Fe(III) ions in B sites by A-site cation vacancies. These effects increase with Mn content. For samples prepared at 600°C, the XRD data and Mössbauer data are interpreted in terms of a higher particle size and lower vacancy content than those found at 400°C. At both temperatures, the cation vacancies found in B-sites are ordered in a γ-Fe 2O 3-type superstructure when the Mn content is lower than 0.6.

  7. Composition, abundance and distribution of Peracarida from the Southern Ocean deep sea

    NASA Astrophysics Data System (ADS)

    Brökeland, Wiebke; Choudhury, Madhumita; Brandt, Angelika

    2007-08-01

    Peracarida are an important component of both the deep-sea fauna and the fauna known from the Antarctic shelf. The peracarid composition from epibenthic-sledge samples obtained during the expeditions ANDEEP I-III is shown and compared to that of other deep-sea basins and the Antarctic shelf. The Amphipoda were the most abundant taxon in the samples, with 43% of all peracarid individuals, followed by the Isopoda (35%), Cumacea (16%), Tanaidacea (5%) and Mysidacea (1%). Highest abundances were found at the shallower stations, but a clear trend towards decreasing abundances with depth could not be confirmed. Although the decrease of amphipod numbers and the increase of isopod numbers with depth in general correspond to other areas, e.g., the Angola Basin, the Southern Ocean deep sea seems to be special by harboring more amphipod specimens at medium depths, thus reflecting the situation on the Antarctic shelf. Outstanding by their number of specimens were the samples from station 133-2 at about 1500 m depth in the Powell Basin, which contained the highest number of specimens, and from station 152-6 in the Bransfield Strait, where the number of specimens was strikingly low despite the moderate depth of about 2000 m.

  8. The Effect of Community on Distributed Bio-inspired Service Composition

    NASA Astrophysics Data System (ADS)

    Carroll, Raymond; Balasubramaniam, Sasitharan; Botvich, Dmitri; Donnelly, William

    The Future Internet is expected to cater for both a larger number and variety of services, which in turn will make basic tasks such as service lifecycle management increasingly important and difficult. At the same time, the ability for users to efficiently discover and compose these services will become a key factor for service providers to differentiate themselves in a competitive market. In previous work, we examined the effect adding biological mechanisms to services had on service management and discovery. In this paper we examine the effects of community on services, specifically in terms of composing services in a distributed fashion. By introducing aspects of community we aim to demonstrate that services can further improve their sustainability and indeed their efficiency.

  9. Distribution and Compositional Constraints on Subsurface Ice in Arcadia Planitia, Mars

    NASA Astrophysics Data System (ADS)

    Bramson, Ali M.; Byrne, Shane; Putzig, Nathaniel E.; Mattson, Sarah; Plaut, Jeffrey J.; Holt, John W.

    2014-11-01

    Knowledge of the present-day quantity and distribution of water ice on Mars can help to understand past Martian climates, and also has implications for future human exploration. Within the northern mid-latitudes, there are many geomorphological features such as ice-exposing impacts (Dundas et al., 2014) and expanded secondary craters (Viola et al., 2014) that are indicative of widespread ice.Impact crater morphology can reveal subsurface structure, such as when terraces form in layered target material (Ormö et al., 2013). We create Digital Terrain Models (DTMs) using the Mars Reconnaissance Orbiter’s HiRISE (High Resolution Imaging Science Experiment) stereo image pairs to measure terrace depths within craters (and thus the depths to the boundary of the subsurface layer). Radar sounding from the SHARAD instrument, also on the Mars Reconnaissance Orbiter, provides an independent mechanism for probing the subsurface and shows an extensive subsurface reflector in Arcadia Planitia (180-225E, 38-50N). Assuming the change in material strengths responsible for the terraces is the same dielectric interface that causes the radar reflectors, combining the terrace depths with radar delay times allows us to determine the radar wave velocity (and thus dielectric constant) of the layer of material between the surface and subsurface reflector.We present results from combining these observational datasets to map the distribution and constrain the dielectric constant of this widespread layer. Preliminary results suggest this decameters-thick layer is relatively pure excess (higher water ice abundances than can fit into the pore spaces of the regolith) ice. We compare our dielectric constant calculations with a 3-component dielectric mixing model to put limits on the porosity and purity of the ice. Understanding the conditions that emplaced and preserved this ice layer is important to improving our understanding of the Martian climate system.

  10. Distribution and Geochemical Composition of Living Planktonic Foraminifera in the Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Jentzen, A.; Schönfeld, J.; Nuernberg, D.

    2014-12-01

    Planktonic foraminifera are widely used for paleoceanographic reconstructions of different water mass dynamics. For accurate reconstruction, it is crucial to understand the habitat, ecology and shell chemistry of single species. In this study, living planktonic foraminifera were collected with a multi closing net in the Caribbean Sea during R/V Meteor cruises M78/1 in 2009, and M94, M95 in 2013 respectively. The population structure in surface to subsurface waters was assessed and related to salinity, temperature and chlorophyll concentrations. Stable isotopes and trace elements of shell calcite are measured to improve the proxy calibration. At all stations, the highest standing stock was observed in the near-surface layer and the highest population densities in the eastern Caribbean Sea. Markedly low abundances of foraminifera were recognized in Gulf of Paria and close to the Orinoco River plume. The most frequent species in the Caribbean were Globigerinoides sacculifer, Globigerinita glutinata, Globigerinoides ruber, Globigerinella calida, and Neogloboquadrina dutertrei. Abundance maxima of G. sacculifer and G. ruber were always recorded in the surface water. The preferred habitat of N. dutertrei was the near-surface mixed layer, even though the species has been commonly referred to calcify in the thermocline. As expected, the deep dweller Globorotalia truncatulinoides (dextral) was mainly observed in upper intermediate waters, although juvenile specimens were found at shallower depths. Plankton tow data showed that shallow-living species adjusted their habitat to surface water masses, which deepened in the southern Caribbean Sea from East to West. Furthermore, intermediate to deep dwellers appear to prevail in surface or subsurface waters during the early stage of their life cycle.

  11. Effect of light-emitting diode (LED) vs. fluorescent (FL) lighting on laying hens in aviary hen houses: Part 2 - Egg quality, shelf-life and lipid composition.

    PubMed

    Long, H; Zhao, Y; Xin, H; Hansen, H; Ning, Z; Wang, T

    2016-01-01

    In this 60-wk study, egg quality, egg shelf-life, egg cholesterol content, total yolk lipids, and yolk fatty acid composition of eggs produced by Dekalb white laying hens in commercial aviary houses with either light-emitting diode (LED) or fluorescent (FL) lighting were compared. All parameters were measured at 27, 40, and 60 wk of age, except for egg shelf-life, which was compared at 50 wk of age. The results showed that, compared to the FL regimen, the LED regimen resulted in higher egg weight, albumen height, and albumen weight at 27 wk of age, thicker shells at 40 wk of age, but lower egg weight at 60 wk of age. Egg quality change was similar between the lighting regimens during the 62-d egg storage study, indicating that LED lighting did not influence egg shelf-life. Eggs from both lighting regimens had similar cholesterol content. However, cholesterol concentration of the yolk (15.9 to 21.0 mg cholesterol/g wet weight yolk) observed in this study was higher than that of United States Department of Agriculture (USDA) database (10.85 mg/g). No significant differences in total lipids or fatty acid composition of the yolks were detected between the two lighting regimens. PMID:26574027

  12. PAH Size, Charge, Composition and Structure Distribution across the Northwest PDR in Reflection Nebula, NGC 7023

    NASA Astrophysics Data System (ADS)

    Allamandola, Louis J.; Allamandola, L. J.; Boersma, C.; Bregman, J. M.; Boersma, C.

    2013-01-01

    PAH emission in the Spitzer-IRS spectral map of the northwest PDR in NGC 7023 was analyzed using the spectra and tools available in the NASA Ames PAH IR Spectroscopic Database, which can be obtained from : www.astrochemistry.org/pahdb. The 5 - 15 m spectrum at each of the 300 pixels comprising the map is fitted using a non-negative-least-square fitting approach. The fits allow decomposition of the emission into four PAH subclasses: size, charge, composition and hydrogen adjacency, i.e., molecular structure. Remarkably, nitrogen-containing PAH cations (PANHs) are required to fit both the 6.2 m and 11.0 m features and stepwise PAH (multi-photon) fragmentation is captured close to the exciting star. The large-scale morphology emerging from the breakdown maps also captures the overall morphological structure of the region determined with traditional astronomical probes. Once past some 20 seconds of arc from the exciting star, the emission is dominated by the more stable, large, symmetric, compact PAH cations in the PDR; with emission from smaller, neutral PAHs taking over along the lines-of-sight towards the more distant molecular cloud. The transition between the diffuse PDR medium and the denser cloud material, as defined by an abrupt intensity change of the H2 emission lines, appears as a distinct discontinuity in the breakdown maps. Further decomposition of the spectral maps into tight principal subclass template emission spectra provides additional insight into the behavior of each PAH subclass. At this point, the general applicability of this template approach is undetermined and awaits further testing. This work demonstrates that analysis of the aromatic infrared bands using the spectra of individual PAHs provides new, fundamental information about the UV-driven, spatial evolution of PAH subpopulations broken down by charge, size and structure, allowing one to connect this evolution with changes in an objects morphology, radiation field, PDR boundaries, etc.

  13. Effect of tissue composition on dose distribution in brachytherapy with various photon emitting sources

    PubMed Central

    Ghorbani, Mahdi; Salahshour, Fateme; Haghparast, Abbas; Knaup, Courtney

    2014-01-01

    Purpose The aim of this study is to compare the dose in various soft tissues in brachytherapy with photon emitting sources. Material and methods 103Pd, 125I, 169Yb, 192Ir brachytherapy sources were simulated with MCNPX Monte Carlo code, and their dose rate constant and radial dose function were compared with the published data. A spherical phantom with 50 cm radius was simulated and the dose at various radial distances in adipose tissue, breast tissue, 4-component soft tissue, brain (grey/white matter), muscle (skeletal), lung tissue, blood (whole), 9-component soft tissue, and water were calculated. The absolute dose and relative dose difference with respect to 9-component soft tissue was obtained for various materials, sources, and distances. Results There was good agreement between the dosimetric parameters of the sources and the published data. Adipose tissue, breast tissue, 4-component soft tissue, and water showed the greatest difference in dose relative to the dose to the 9-component soft tissue. The other soft tissues showed lower dose differences. The dose difference was also higher for 103Pd source than for 125I, 169Yb, and 192Ir sources. Furthermore, greater distances from the source had higher relative dose differences and the effect can be justified due to the change in photon spectrum (softening or hardening) as photons traverse the phantom material. Conclusions The ignorance of soft tissue characteristics (density, composition, etc.) by treatment planning systems incorporates a significant error in dose delivery to the patient in brachytherapy with photon sources. The error depends on the type of soft tissue, brachytherapy source, as well as the distance from the source. PMID:24790623

  14. Diversity, composition, and geographical distribution of microbial communities in California salt marsh sediments

    USGS Publications Warehouse

    Cordova-Kreylos, A. L.; Cao, Y.; Green, P.G.; Hwang, H.-M.; Kuivila, K.M.; LaMontagne, M.G.; Van De Werfhorst, L. C.; Holden, P.A.; Scow, K.M.

    2006-01-01

    The Pacific Estuarine Ecosystem Indicators Research Consortium seeks to develop bioindicators of toxicant-induced stress and bioavailability for wetland biota. Within this framework, the effects of environmental and pollutant variables on microbial communities were studied at different spatial scales over a 2-year period. Six salt marshes along the California coastline were characterized using phospholipid fatty acid (PLFA) analysis and terminal restriction fragment length polymorphism (TRFLP) analysis. Additionally, 27 metals, six currently used pesticides, total polychlorinated biphenyls and polycyclic aromatic hydrocarbons, chlordanes, nonachlors, dichlorodiphenyldichloroethane, and dichlorodiphenyldichloroethylene were analyzed. Sampling was performed over large (between salt marshes), medium (stations within a marsh), and small (different channel depths) spatial scales. Regression and ordination analysis suggested that the spatial variation in microbial communities exceeded the variation attributable to pollutants. PLFA analysis and TRFLP canonical correspondence analysis (CCA) explained 74 and 43% of the variation, respectively, and both methods attributed 34% of the variation to tidal cycles, marsh, year, and latitude. After accounting for spatial variation using partial CCA, we found that metals had a greater effect on microbial community composition than organic pollutants had. Organic carbon and nitrogen contents were positively correlated with PLFA biomass, whereas total metal concentrations were positively correlated with biomass and diversity. Higher concentrations of heavy metals were negatively correlated with branched PLFAs and positively correlated with methyl- and cyclo-substituted PLFAs. The strong relationships observed between pollutant concentrations and some of the microbial indicators indicated the potential for using microbial community analyses in assessments of the ecosystem health of salt marshes. Copyright ?? 2006, American Society for Microbiology. All Rights Reserved.

  15. Exclusive Breastfeeding and Other Foods in the First Six Months of Life: Effects on Nutritional Status and Body Composition of Brazilian Children

    PubMed Central

    Magalhães, Taís C. A.; Vieira, Sarah A.; Priore, Silvia E.; Ribeiro, Andréia Q.; Lamounier, Joel A.; Franceschini, Sylvia C. C.; Sant'Ana, Luciana F. R.

    2012-01-01

    Objective. To evaluate the effect of exclusive breastfeeding and consumption of other foods in the first six months of life in the nutritional status and body composition of children. Methods. A retrospective cohort study with 185 children aged from 4 to 7 years was monitored during the first months of life in a program of support to breastfeeding. We evaluated weight, height, waist circumference, and body composition by using DEXA. The nutritional status was assessed by the BMI/age index. The parameters of adiposity were classified by using as the cutoff point, the 85th percentile of the sample itself, according to gender and age. Confounding factors considered were variables related to maternal, pregnancy, birth, sociodemographic, health, lifestyle, and diet. Bivariate and multivariate analyses were performed, the latter by means of multiple logistic regression. Results. The median exclusive breastfeeding was 3 months. Of the children, 42.7% received cow's milk and 35.7% received infant formula. Regarding nutritional status, 21.1% of the children showed changes. The variables of infant feeding were not independently associated with nutritional status and body composition of the children and there were no differences between the groups studied. Conclusion. Breastfeeding was not a protective factor to overweight and body fat in children. PMID:23193378

  16. Distribution, abundance and carbon isotopic composition of gaseous hydrocarbons in Big Soda Lake, Nevada - An alkaline, meromictic lake

    NASA Technical Reports Server (NTRS)

    Oremland, R. S.; Des Marais, D. J.

    1983-01-01

    The study of the distribution and isotopic composition of low molecular weight hydrocarbon gases at the Big Soda Lake, Nevada, has shown that while neither ethylene nor propylene were found in the lake, ethane, propane, isobutane and n-butane concentrations all increased with water column depth. It is concluded that methane has a biogenic origin in both the sediments and the anoxic water column, and that C2-C4 alkanes have biogenic origins in the monimolimnion water and shallow sediments. The changes observed in delta C-13/CH4/ and CH4/(C2H6 + C3H8) with depth in the water column and sedimeents are probably due to bacterial processes, which may include anaerobic methane oxidation and different rates of methanogenesis, and C2-to-C4 alkane production by microorganisms.

  17. Marine litter in the upper São Vicente submarine canyon (SW Portugal): Abundance, distribution, composition and fauna interactions.

    PubMed

    Oliveira, Frederico; Monteiro, Pedro; Bentes, Luis; Henriques, Nuno Sales; Aguilar, Ricardo; Gonçalves, Jorge M S

    2015-08-15

    Marine litter has become a worldwide environmental problem, tainting all ocean habitats. The abundance, distribution and composition of litter and its interactions with fauna were evaluated in the upper S. Vicente canyon using video images from 3 remote operated vehicle exploratory dives. Litter was present in all dives and the abundance was as high as 3.31 items100m(-1). Mean abundance of litter over rock bottom was higher than on soft substrate. Mean litter abundance was slightly higher than reported for other canyons on the Portuguese margin, but lower in comparison to more urbanized coastal areas of the world. Lost fishing gear was the prevalent type of litter, indicating that the majority of litter originates from maritime sources, mainly fishing activity. Physical contact with sessile fauna and entanglement of specimens were the major impacts of lost fishing gear. Based on the importance of this region for the local fishermen, litter abundance is expected to increase. PMID:26051154

  18. The evolution and distribution of life in the Precambrian eon-global perspective and the Indian record.

    PubMed

    Sharma, M; Shukla, Y

    2009-11-01

    The discovery of Precambrian microfossils in 1954 opened a new vista of investigations in the field of evolution of life. Although the Precambrian encompasses 87% of the earth's history, the pace of organismal evolution was quite slow. The life forms as categorised today in the three principal domains viz. the Bacteria, the Archaea and the Eucarya evolved during this period. In this paper, we review the advancements made in the Precambrian palaeontology and its contribution in understanding the evolution of life forms on earth. These studies have enriched the data base on the Precambrian life. Most of the direct evidence includes fossil prokaryotes, protists, advanced algal fossils, acritarchs, and the indirect evidence is represented by the stromatolites, trace fossils and geochemical fossils signatures. The Precambrian fossils are preserved in the form of compressions, impressions, and permineralized and biomineralized remains. PMID:20009270

  19. Aerosol size distribution, composition, and CO sub 2 backscatter at Mauna Loa Observatory

    SciTech Connect

    Clarke, A.D.; Porter, J.N. )

    1991-03-20

    Continuous measurements of aerosol size distributions were obtained during Jan-Mar and Nov-Dec periods of 1988 at Mauna Loa Observatory, Hawaii. These periods were chosen in order to characterize aerosol physiochemistry during periods representative of low-dust atmospheric conditions and periods associated with appreciable Asian dust transport to that site. Size distributions for particles with diameters between 0.15 and 7.6 {mu}m were accumulated in 256 size bins of a laser optical particle counter for 3-hour intervals during most of the period. The aerosol sample stream was heated to selected temperatures in order to provide size-discriminated measurements of aerosol volatility. Resulting data were used to assess the variability in aerosol concentrations and properties related to aerosol backscatter values at a wavelength of 10.6 {mu}m, {beta}{sub CO{sub 2}}, in the mid-troposphere. Low aerosol concentrations, considered representative of mid-tropospheric air, occurred in downslope flow between midnight and sunrise. Measurements for these time periods suggest that {beta}{sub CO{sub 2}} varied from a low of about 5 {times} 10{sup {minus}12}m{sup {minus}1}sr{sup {minus}1} to a high of 5 {times} 10{sup {minus}8}m{sup {minus}1}sr{sup {minus}1}. Coarse particles with diameters between 1.0 and 5.0 {mu}m account for most of the derived values of {beta}{sub CO{sub 2}} at all but the highest and lowest aerosol mass concentrations. Volatile aerosol appears to dominate aerosol mass during the cleanest periods but was a small fraction of the total during dust events. The authors estimate that minimum values for {beta}{sub CO{sub 2}} at about 8 km should usually fall in the range of 1-3 {times} 10{sup {minus}12}m{sup {minus}1}sr{sup {minus}1} and be dominated by a sulfate aerosol.

  20. Changes in body composition and fat distribution after short-term weight gain in patients with anorexia nervosa.

    PubMed

    Orphanidou, C I; McCargar, L J; Birmingham, C L; Belzberg, A S

    1997-04-01

    The most commonly described psychologic abnormality associated with anorexia nervosa is a distorted perception of body weight and shape. This perception may contribute to the anorexic patient's resistance to gaining weight even when it is a medical necessity. The purpose of this study was to assess body-composition and fat-distribution changes after short-term weight gain in 26 female anorexia nervosa patients 27.6 +/- 6.6 (mean +/- SD) y of age, with a body mass index (BMI; in kg/m2) of 16.5 +/- 1.9. They participated in a refeeding protocol both as inpatients (n = 21) and as outpatients (n = 5) until they achieved maximum weight gain. Body-composition and fat-distribution changes were measured by using dual-energy X-ray absorptiometry (DXA) and skinfold thickness and circumference measurements. A mean weight gain of 6.7 +/- 5.3 kg (P < 0.001) was observed, which included significant increases in body fat (P < 0.001), lean body mass (P < 0.05), and bone mineral content (P < 0.01), with body fat being the component that increased the most. When measured by DXA, fat gain was not significantly different among the three central regions: subscapular, 1.7 +/- 1.2 kg; waist, 1.8 +/- 1.3 kg; and thigh, 1.5 +/- 1.0 kg (P = 0.10). Thus, although fat was the largest component of the weight gained, there was no preferential fat deposition in any one area and the female gynoid body shape was maintained. PMID:9094890

  1. The Influence of the Extreme Ultraviolet Spectral Energy Distribution on the Structure and Composition of the Upper Atmosphere of Exoplanets

    NASA Astrophysics Data System (ADS)

    Guo, J. H.; Ben-Jaffel, Lotfi

    2016-02-01

    By varying the profiles of stellar extreme ultraviolet (EUV) spectral energy distributions (SEDs), we tested the influences of stellar EUV SEDs on the physical and chemical properties of an escaping atmosphere. We apply our model to study four exoplanets: HD 189733b, HD 209458b, GJ 436b, and Kepler-11b. We find that the total mass loss rates of an exoplanet, which are determined mainly by the integrated fluxes, are moderately affected by the profiles of the EUV SED, but the composition and species distributions in the atmosphere can be dramatically modified by the different profiles of the EUV SED. For exoplanets with a high hydrodynamic escape parameter (λ), the amount of atomic hydrogen produced by photoionization at different altitudes can vary by one to two orders of magnitude with the variation of stellar EUV SEDs. The effect of photoionization of H is prominent when the EUV SED is dominated by the low-energy spectral region (400-900 Å), which pushes the transition of H/H+ to low altitudes. In contrast, the transition of H/H+ moves to higher altitudes when most photons are concentrated in the high-energy spectral region (50-400 Å). For exoplanets with a low λ, the lower temperatures of the atmosphere make many chemical reactions so important that photoionization alone can no longer determine the composition of the escaping atmosphere. For HD 189733b, it is possible to explain the time variability of Lyα between 2010 and 2011 by a change in the EUV SED of the host K-type star, yet invoking only thermal H i in the atmosphere.

  2. Properties of wine polymeric pigments formed from anthocyanin and tannins differing in size distribution and subunit composition.

    PubMed

    Bindon, Keren; Kassara, Stella; Hayasaka, Yoji; Schulkin, Alex; Smith, Paul

    2014-11-26

    To explore the effect of tannin composition on pigment formation, model ferments of purified 3-O-monoglucoside anthocyanins (ACN) were conducted either alone or in the presence of two different tannins. Tannins were isolated from grape seeds (Sd) or skins (Sk) following exhaustive extraction in 70% v/v acetone. The Sd and Sk tannin fractions had a mean degree of polymerization of 5.2 and 25.6, respectively. The Sd fraction was highly galloylated, at 22%, but galloylation was <2% in the Sk fraction. The Sk fraction was distinguished by a high proportion of prodelphinidin, at 58%. After a 6 month aging period, polymeric pigments were quantified and their color properties determined following isolation by solid-phase extraction. Wine color and polymeric pigment were highest in the treatment containing ACN+Sd and similar in the ACN+Sk and ACN treatments. The same trend between treatments was observed for total and polymeric nonbleachable pigments. Only minor changes in tannin subunit composition were found following ACN incorporation, but the size distribution of polymeric pigments determined by gel permeation chromatography decreased, in particular for the ACN+Sk treatment. Color incorporation in the higher molecular mass range was lower for ACN+Sk wines than for ACN+Sd wines. Compositional differences between the two tannin fractions may therefore limit the incorporation of ACNs in the colored form. The results suggest that in the ACN+Sk and ACN treatments, the formation of lower molecular mass oligomeric pigments was favored. In polymeric pigments derived from ACNs, the presence of ethyl- and vinyl-linked ACNs to the level of trimers was identified using mass spectrometry. PMID:25356846

  3. Amino Acid Composition, Molecular Weight Distribution and Gel Electrophoresis of Walnut (Juglans regia L.) Proteins and Protein Fractionations

    PubMed Central

    Mao, Xiaoying; Hua, Yufei; Chen, Guogang

    2014-01-01

    As a by-product of oil production, walnut proteins are considered as an additional source of plant protein for human food. To make full use of the protein resource, a comprehensive understanding of composition and characteristics of walnut proteins are required. Walnut proteins have been fractionated and characterized in this study. Amino acid composition, molecular weight distribution and gel electrophoresis of walnut proteins and protein fractionations were analyzed. The proteins were sequentially separated into four fractions according to their solubility. Glutelin was the main component of the protein extract. The content of glutelin, albumin, globulin and prolamin was about 72.06%, 7.54%, 15.67% and 4.73% respectively. Glutelin, albumin and globulin have a balanced content of essential amino acids, except for methionine, with respect to the FAO pattern recommended for adults. SDS-PAGE patterns of albumin, globulin and glutelin showed several polypeptides with molecular weights 14.4 to 66.2 kDa. The pattern of walnut proteins in two-dimension electrophoresis (2-DE) showed that the isoelectric point was mainly in the range of 4.8–6.8. The results of size exclusion chromatogram indicated molecular weight of the major components of walnut proteins were between 3.54 and 81.76 kDa. PMID:24473146

  4. Effects of different ceramic and composite materials on stress distribution in inlay and onlay cavities: 3-D finite element analysis.

    PubMed

    Yamanel, Kivanç; Caglar, Alper; Gülsahi, Kamran; Ozden, Utku Ahmet

    2009-11-01

    To reduce loss of tooth tissue and to improve esthetic results, inlay and onlay restorations are good treatment choices for extensive cavities in posterior teeth. The aim of this paper was to evaluate, by means of three-dimensional finite element analysis, the effects of restorative material and cavity design on stress distribution in the tooth structures and restorative materials. Two different nanofilled composites and two different all-ceramic materials were used in this study. A permanent molar tooth was modeled with enamel and dentin structures. 3-D inlay and onlay cavity designs were created. Von Mises, compressive, and tensile stresses on the restorative materials, core materials, enamel, and dentin were evaluated separately. On the effect of restorative material, results showed that in the case of materials with low elastic moduli, more stress was transferred to the tooth structures. Therefore, compared to the nanofilled composites, the all-ceramic inlay and onlay materials tested transferred less stress to the tooth structures. On the effect of cavity design, the onlay design was more efficacious in protecting the tooth structures than the inlay design. PMID:20019416

  5. Amphiura filiformis (Ophiuroidea: Echinodermata) in the North Sea. Distribution, present and former abundance and size composition

    NASA Astrophysics Data System (ADS)

    Duineveld, G. C. A.; Künitzer, A.; Heyman, R. P.

    During the North Sea Benthos Survey undertaken by the ICES Benthos Ecology Working Group in spring 1986, a synoptic inventory was made of the benthos in the southern, central and part of the northern North Sea. The present paper deals with the status of the population of the infaunal ophiuroid Amphiura filiformis on the basis of measurements from 150 stations. A. filiformis was found at all the offshore muddy stations, but densities were generally highest in the shallow area south of the Dogger Bank. Stations with more than 1000 ind·m -2 were mainly situated near the frontiers between turbid and summer-stratified water masses, viz. along the southern border of the Oyster Ground, the southern slope of the Dogger Bank and in the northern part of the Pleistocene Elbe river valley. The size-distributions of A. filiformis show that juveniles were generally scarce at stations with high numbers of adults, whereas highest numbers of juveniles occur at stations with few adults. An unequivocal relation between adults and juveniles was, however, absent. This stresses the importance of other factors involved in recruitment. Comparison between the present and former (1938 and 1950) density of A. filiformis suggests that density has increased in the shallower parts but has remained stable in the deeper northern North Sea. An increase of A. filiformis shallow part of the North Sea could point to an enhanced food supply for the benthos, which may have some relation to the eutrophication in nearshore areas.

  6. Optimization of stresses in the end-fittings of composite insulators for distribution and transmission lines

    SciTech Connect

    Lanteigne, J.; Lalonde, S.; Tourreil, C. de

    1995-11-01

    This paper addresses the problem of stress calculation and optimization in a FRP (Fiberglass Reinforced Plastic) pultruded rod crimped into a metal end-fitting. This type of assembly is used mainly for suspension and line post insulators. The authors discuss herein some aspects that merit consideration in any given design approach. In many respects FRP pultruded materials are anisotropic. The anisotropy of their elastic constants influences the distribution of stresses while the anisotropy of their mechanical properties (ultimate strengths) limits their load carrying capacity. Finally, the anisotropy of their failure modes governs the progression and the spread of the damage. Each level of anisotropy will be discussed distinctly. Geometrical considerations are also necessary to arrive at an efficient design. Namely, the authors will consider the frictional interactions between the end-fitting inner wall and the rod, then they will present their approach in selecting the appropriate L/D ratio (i.e. the ratio of the end-fitting length over the rod diameter), and finally they will discuss the influence of the compression profile, i.e. the permanent radial displacement imparted to the rod due to the action of the crimping force.

  7. Species Composition and Seasonal Distribution of Mosquito Larvae (Diptera: Culicidae) in Southern New Jersey, Burlington County.

    PubMed

    Verna, Thomas N

    2015-09-01

    A total of 36,495 larvae consisting of 45 species from 11 genera were collected from 7,189 sites from southern New Jersey, Burlington County between the months of March and October, 2001-2014. Density and seasonal distribution were determined among natural and artificial habitat. The most dominant species collected from natural habitat was Aedes vexans (Meigen) followed by Ochlerotatus canadensis canadensis (Theobald), Culex restuans Theobald, Culex pipiens L., and Culex territans Walker. The most dominant species collected from artificial habitat was Aedes albopictus (Skuse) followed by Ochlerotatus japonicus japonicus (Theobald), Cx. restuans, Cx. pipiens, and Ochlerotatus triseriatus (Say). Cx. restuans and Cx. pipiens were the only species categorized as dominant among both natural and artificial habitat and comprised greater than half the total density. Sympatry was common among dominant species from artificial habitat where a significant percentage of the total collection contained multiple species. The most common types of natural habitats were forested depressions and stream flood plains whereas rimless vehicle tires and various plastic containers were the most common artificial habitats. The pitcher plant Sarracenia purpurea L. was the only habitat exclusive to one species. PMID:26336214

  8. Snow-borne nanosized particles: Abundance, distribution, composition, and significance in ice nucleation processes

    NASA Astrophysics Data System (ADS)

    Rangel-Alvarado, Rodrigo Benjamin; Nazarenko, Yevgen; Ariya, Parisa A.

    2015-11-01

    Physicochemical processes of nucleation constitute a major uncertainty in understanding aerosol-cloud interactions. To improve the knowledge of the ice nucleation process, we characterized physical, chemical, and biological properties of fresh snow using a suite of state-of-the-art techniques based on mass spectrometry, electron microscopy, chromatography, and optical particle sizing. Samples were collected at two North American Arctic sites, as part of international campaigns (2006 and 2009), and in the city of Montreal, Canada, over the last decade. Particle size distribution analyses, in the range of 3 nm to 10 µm, showed that nanosized particles are the most numerous (38-71%) in fresh snow, with a significant portion (11 to 19%) less than 100 nm in size. Particles with diameters less than 200 nm consistently exhibited relatively high ice-nucleating properties (on average ranged from -19.6 ± 2.4 to -8.1 ± 2.6°C). Chemical analysis of the nanosized fraction suggests that they contain bioorganic materials, such as amino acids, as well as inorganic compounds with similar characteristics to mineral dust. The implication of nanoparticle ubiquity and abundance in diverse snow ecosystems are discussed in the context of their importance in understanding atmospheric nucleation processes.

  9. Hydrothermal processing of duckweed: effect of reaction conditions on product distribution and composition.

    PubMed

    Duan, Peigao; Chang, Zhoufan; Xu, Yuping; Bai, Xiujun; Wang, Feng; Zhang, Lei

    2013-05-01

    Influences of operating conditions such as temperature (270-380 °C), time (10-120 min), reactor loading (0.5-5.5 g), and K2CO3 loading (0-50 wt.%) on the product (e.g. crude bio-oil, water soluble, gas and solid residue) distribution from the hydrothermal processing of duckweed were determined. Of the four variables, temperature and K2CO3 loading were always the most influential factors to the relative amount of each component. The presence of K2CO3 is unfavorable for the production of bio-oil and gas. Hydrothermal processing duckweed produces a bio-oil that is enriched in carbon and hydrogen and has reduced levels of O compared with the original duckweed feedstock. The higher heating values of the bio-oil were estimated within the range of 32-36 MJ/kg. Major bio-oil constituents include ketones and their alkylated derivatives, alcohols, heterocyclic nitrogen-containing compounds, saturated fatty acids and hydrocarbons. The gaseous products were mainly CO2 and H2, with lesser amounts of CH4 and CO. PMID:23021946

  10. Kinetic modeling of the composition and dynamics of volatile's distribution in Europa's exosphere

    NASA Astrophysics Data System (ADS)

    Tenishev, V.; Borovikov, D.; Tucker, O. J.; Combi, M. R.; Rubin, M.; Jia, X.; Gombosi, T. I.

    2014-12-01

    The surface-bound Europa's exosphere is tightly connected to both the Jovian magnetosphere as well as to Europa's icy surface. The neutral species in the exosphere are mostly produced by the Jovian magnetospheric ion sputtering of the water ice surface and direct ejection from Europa's plume. Here, we present results of our model study of the distribution of the neutral species in Europa's exosphere, their escape and migration over the moon's surface. The work is a part of a more global effort aimed at fully coupled understanding of the interaction between Europa's exosphere and Jovian magnetosphere. The modeled neutral species are produced via sputtering (O2 and H2O), directly ejected into the plume (H2O), or produced via photolytic or electron impact reactions (OH, O2, O, H). The computational domain extends to altitudes up to ~10 RE, which exceeds the radius of Europa's Hill sphere (~8.5 RE, Miljkovic et al., 2012). Jupiter's and Europa's gravity are taken into consideration. The modeling is performed using our kinetic Adaptive Mesh Particle Simulator (Tenishev et al., 2013), where the exospheric species are represented by a large set of the model particles governed by the same physical laws as those of the real exosphere. The calculated HI and OI brightness synthetic images are compared with those obtained with Hubble Space Telescope (Roth et al., 2014).

  11. Pore Distribution and Water Uptake in a Cenosphere-Cement Paste Composite Material

    NASA Astrophysics Data System (ADS)

    Baronins, J.; Setina, J.; Sahmenko, G.; Lagzdina, S.; Shishkin, A.

    2015-11-01

    Alumina silicate cenospheres (CS) is a significant waste material from power plants that use a coal. Use CS as Portland cement replacement material gives opportunity to control physical and mechanical properties and makes a product lighter and more cost-effective. In the frame of this study, Portland cement paste samples were produced by adding CS in the concentration range from 0 to 40 volume %. Water uptake of hardened samples was checked and pore size distribution by using the mercury porosimetry was determined. In a cold climate where the temperature often falls below 0 °C, it is important to avoid the amount of micrometer sized pores in the final structure and to decrease water absorption capacity of material. In winter conditions, water fills such pores and causes additional stresses to their walls by expansion while freezing. It was found that generally water uptake capacity for cement paste samples decreased up to 20% by increasing the concentration of CS up to 40 volume %, at the same time, the volume of micrometer sized opened pores increases.

  12. Spatial distribution of summertime particulate matter and its composition in Greece

    NASA Astrophysics Data System (ADS)

    Tsiflikiotou, Maria; Papanastasiou, Dimitris; Zarmpas, Paulos; Paraskevopoulou, Despoina; Diapouli, Evangelia; Kostenidou, Evangelia; Kaltsonoudis, Christos; Bougiatioti, Aikaterini; Theodosi, Christina; Kouvarakis, George; Liakakou, Eleni; Vassilatou, Vassiliki; Siakavaras, Dimitris; Biskos, George; Eleftheriadis, Konstantinos; Gerasopoulos, Evangelos; Mihalopoulos, Nikos; Pandis, Spyros

    2014-05-01

    A field campaign was conducted in Greece during the summer of 2012 (8 June - 26 July) to investigate ambient particulate matter (PM) levels, chemical composition and contribution of regional and local sources. Simultaneous collection of PM1, PM2.5 and PM10 samples from seven different sampling sites in Greece were collected, two sites in Athens - Ag. Paraskevi Demokritos campus (suburban background), - Penteli (National Observatory of Athens NOA premises, suburban background), one in Thessaloniki (suburban background), two stations in Patras - Centre (urban background), - suburbs/ICE FORTH campus (suburban background), one at Finokalia in the northeast part of Crete (remote background) and the last one at the Navarino Environmental Observatory (NEO) in southwest Peloponnese (rural background). These different background sites were chosen in order to estimate both the local emissions sources and the long range transport. A suite of continuous/online instruments were deployed in selected sites including an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF AMS), an Aerosol Chemical Speciation Monitor (ACSM), a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), a Tapered Element Oscillating Microbalance (TEOM), Nephelometers and Aethalometers, gas-phase monitors, etc. The collected filter samples from all sites were analyzed for major ions, OC/EC, metals, etc. The fine PM mass concentration and chemical measurements were quite similar in all sites suggesting significant contributions of transported regional pollution and smaller contributions of local sources. The campaign average PM2.5 ranged from 17.5 to 20 μg m-3 for the different sites. The Athens suburban site in Demokritos had the highest concentration PM2.5 levels. Sulphates and organics were the major PM2.5 components while nitrates, mineral dust and sea-salt for the coastal areas were also important for the PM10 fraction. The sulphate levels were similar in all sites, while the concentration of the organics and mineral dust were more variable. Most of the organic aerosol was highly oxygenated.

  13. Impact of prebiotic synthesis and diagenesis on the distribution, stereochemistry, and stable isotope composition of amino acids in carbonaceous meteorites

    NASA Astrophysics Data System (ADS)

    Engel, Michael H.

    2013-09-01

    Simulation experiments for prebiotic synthesis result in racemic mixtures (D/L = 1.0) for protein and non-protein amino acids, irrespective of the composition of the precursor gas mixtures or the energy sources employed. It is therefore not surprising that it was commonly assumed that if amino acids in carbonaceous meteorites were formed by similar reactions they would also be racemic. Engel and Nagy1 and more recently Glavin et al.2 have shown that protein amino acids in carbonaceous meteorites often exhibit a moderate to strong L-amino acid excess (D/L ˂ 1.0). Engel3 hypothesized that this extraterrestrial L-excess might be the precursor material from which life as we know it originated. Stable isotope analysese.g 4 confirmed that the L-amino acid excess in meteorites was indigenous rather than the result of contamination subsequent to impact on Earth. A key question that arises is that since there are no known mechanisms for the direct prebiotic synthesis of amino acids with an L-enantiomer excess, how did these compounds come to exist in carbonaceous meteorites? It has been proposed5 and references therein that a series of diagenetic reactions subsequent to synthesis are responsible for the L-enantiomer excess. In this paper, this hypothesis is further explored with respect to explaining the range of D/L values for amino acids in the various types of carbonaceous meteorites as well as in different stones of the same meteorite. Possible effects of diagenesis on the stable isotope compositions of these compounds are also addressed.

  14. Species composition and distribution of bivalves in bathyal and abyssal depths of the Sea of Japan

    NASA Astrophysics Data System (ADS)

    Kamenev, Gennady M.

    2013-02-01

    Twenty-six bivalve species collected by four Russian (1972, 1976, 1985, 2005) and Russian-German (2010) expeditions in the bathyal and abyssal depths of the Sea of Japan (465-3435 m) are listed with the material examined and illustrated. Taxonomic decisions herein: Robaia habei Scarlato, 1981 is synonymized with Nuculana (Robaia) robai (Kuroda, 1929); following Scarlato (1981) and Coan et al. (2000)Dacrydium nipponicum Okutani, 1975 and Dacrydium minimum Okutani and Izumidate, 1992 are synonymized with Dacrydium vitreum (Möller, 1842); Maorithyas yamatotaensis Okutani and Izumidate, 1992 is synonymized with Adontorhina cyclia Berry, 1947; Axinopsida rubiginosa Okutani and Izumidate, 1992 is synonymized with Mendicula ferruginosa (Forbes, 1844); Cardiomya lindbergi batialis Scarlato, 1972 is synonymized with Cardiomya tosaensis (Kuroda, 1948); Cuspidaria sadoensis Okutani and Ito, 1983 is synonymized with Cuspidaria ascoldica Scarlato, 1972; Cyclocardia rjabininae (Scarlato, 1955) recognized as valid and distinct from Cyclocardia ovata (Rjabinina, 1952). The deep-water bivalve fauna of the Sea of Japan is characterized by an impoverished shelf fauna and consists of eurybathic species that extend from the shelf to the bathyal and abyssal zones. Most of them have a wide geographic distribution and inhabit cold water regions of the Northern Atlantic, Northern Pacific, and Arctic Ocean. Only five species are endemic to the Sea of Japan. With increase in depth, the species richness of bivalves decreases. In the depth range from 200 to 1600 m, all species (26) found in the deep Sea of Japan were recorded, while only 10 species were recorded in the lower bathyal slope (1700-3000 m). At depths below 3000 m, only D. vitreum, Delectopecten vancouverensis (Whiteaves, 1893), and Thyasira (Parathyasira) sp. were found. The lack of typical abyssal species of bivalves in the deep Sea of Japan is probably connected with the isolation of this body of water from the Pacific abyssal depths.

  15. Automated Measurements of Ambient Aerosol Chemical Composition and its Dry and Wet Size Distributions at Pittsburgh Supersite

    NASA Astrophysics Data System (ADS)

    Khlystov, A. Y.; Stanier, C.; Chun, W.; Vayenas, D.; Mandiro, M.; Pandis, S. N.

    2001-12-01

    Ambient aerosol particles change size with changes in ambient relative humidity. The magnitude of the size change depends on the hygroscopic properties of the particles, which is determined by their chemical composition. Hygroscopic properties of particles influence many environmentally important aerosol qualities, such as light scattering and partitioning between the gas and particle phases of semivolitile compounds. Studying the hygroscopic growth of ambient particles is thus of paramount importance. The highroscopic growth of ambient particles and their chemical composition are measured continuously within the Pittsburgh Air Quality Study (EPA supersite program). The hygroscopic size changes are measured using an automated system built for this study. The system consists of two Scanning Mobility Particle Sizers (SMPS, TSI Inc.) and an Aerodynamic Particle Sizer (APS, TSI Inc.). The three instruments measure aerosol size distribution between 5 nanometers and 10 micrometers in diameter. The inlets of the instruments and the sheath air lines of the SMPS systems are equipped with computer controlled valves that direct air through Nafion dryers (PermaPure Inc.) or bypass them. The Nafion dryers are drying the air stream below 40% RH at which point ambient particles are expected to lose most or all water and thus be virtually dry. To avoid changes in relative humidity and evaporation of volatile particles due to temperature differences the system is kept at ambient temperature. The system measures alternatively dry (below 40% RH) and wet (actual ambient RH) aerosol size distributions every 6 minutes. The hygroscopic growth observed with the size-spectrometer system is compared with theoretic predictions based on the chemical composition of aerosol particles. A modified semi-continuous Steam-Jet Aerosol Collector provides the total available budget (particles and gas) of water-soluble species, which is used as an input to the thermodynamic model. The model calculates the aerosol/gas partitioning of semivolatile species including water and thus predicts the hygroscopic growth of particles. Preliminary data on the measured hygroscopic growth factors of ambient aerosol and a comparison with the model predictions will be discussed.

  16. Investigation of the Composition and Electromagnetic Properties of Lithium Ferrite LiFe5O8 Ceramics Synthesized from Ultradisperse Iron Oxide

    NASA Astrophysics Data System (ADS)

    Surzhikov, A. P.; Lysenko, E. N.; Malyshev, A. V.; Nikolaev, E. V.; Zhuravkov, S. P.; Vlasov, V. A.

    2015-02-01

    Structural, magnetic, and electric characteristics of LiFe5O8 synthesized from ultradisperse iron oxide powder are investigated. The basic Fe2O3 reagent is prepared by oxidation of iron nanopowder with particle sizes of 100 nm synthesized by the electroexplosive method. It is demonstrated that LiFe5O8 is characterized by fine-grained ceramic structure with average grain size of 1.4 μm, high values of the Curie temperature (~630°C), specific electrical resistance (107 Ωṡcm), and saturation magnetization (>3300 G). Thus, lithium ferrite so obtained without additives has the parameters suitable for its application as a microwave ferrite material. It is also demonstrated that addition of bismuth ferrite to the lithium ferrite composition during its sintering yields lower values of the specific electrical resistance and relatively high values of the density and saturation magnetization.

  17. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions. [Patent application

    DOEpatents

    Mrazek, F.C.; Smaga, J.A.; Battles, J.E.

    1981-01-19

    A positive electrode for a secondary electrochemical cell is described wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

  18. Mortality of the oldest old Chinese: The role of early-life nutritional status, socioeconomic conditions, and sibling sex-composition

    PubMed Central

    Huang, Cheng; Elo, Irma T.

    2010-01-01

    Based on a nationally representative sample of 8,099 Chinese drawn from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), this study investigated the long-term health consequences of early-life nutritional status, sibling sex-composition, childhood socioeconomic conditions, and place of birth on mortality at ages 80 and above between 1998 and 2005. Better nutritional status in childhood predicted lower mortality at ages 80 and above, net of childhood circumstances, adult socioeconomic status, and health behaviors. In addition, sibling sex composition had long-term health consequences, net of childhood and adult characteristics, such that women benefited from having grown up in families with only daughters, while men benefited from having grown up in families with both sons and daughters. Childhood socioeconomic status was only marginally related to old-age mortality and this association was attenuated further by the inclusion of adult characteristics. Place of birth was not a significant predictor of old-age mortality. PMID:19184718

  19. Revisiting spatial distribution and biochemical composition of calcium-containing crystals in human osteoarthritic articular cartilage

    PubMed Central

    2013-01-01

    Introduction Calcium-containing (CaC) crystals, including basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPP), are associated with destructive forms of osteoarthritis (OA). We assessed their distribution and biochemical and morphologic features in human knee OA cartilage. Methods We prospectively included 20 patients who underwent total knee replacement (TKR) for primary OA. CaC crystal characterization and identification involved Fourier-transform infra-red spectrometry and scanning electron microscopy of 8 to 10 cartilage zones of each knee, including medial and lateral femoral condyles and tibial plateaux and the intercondyle zone. Differential expression of genes involved in the mineralization process between cartilage with and without calcification was assessed in samples from 8 different patients by RT-PCR. Immunohistochemistry and histology studies were performed in 6 different patients. Results Mean (SEM) age and body mass index of patients at the time of TKR was 74.6 (1.7) years and 28.1 (1.6) kg/m², respectively. Preoperative X-rays showed joint calcifications (chondrocalcinosis) in 4 cases only. The medial femoro-tibial compartment was the most severely affected in all cases, and mean (SEM) Kellgren-Lawrence score was 3.8 (0.1). All 20 OA cartilages showed CaC crystals. The mineral content represented 7.7% (8.1%) of the cartilage weight. All patients showed BCP crystals, which were associated with CPP crystals for 8 joints. CaC crystals were present in all knee joint compartments and in a mean of 4.6 (1.7) of the 8 studied areas. Crystal content was similar between superficial and deep layers and between medial and femoral compartments. BCP samples showed spherical structures, typical of biological apatite, and CPP samples showed rod-shaped or cubic structures. The expression of several genes involved in mineralization, including human homolog of progressive ankylosis, plasma-cell-membrane glycoprotein 1 and tissue-nonspecific alkaline phosphatase, was upregulated in OA chondrocytes isolated from CaC crystal-containing cartilages. Conclusions CaC crystal deposition is a widespread phenomenon in human OA articular cartilage involving the entire knee cartilage including macroscopically normal and less weight-bearing zones. Cartilage calcification is associated with altered expression of genes involved in the mineralisation process. PMID:24004678

  20. The Effect of Carbon Layer Variations in Carbon/Porous Silicon Composite Rugate Filters for End-of-Service-Life Indicators

    NASA Astrophysics Data System (ADS)

    Gofus, John Stephen, III

    Carbon/porous silicon composite rugate filters, for use as end-of service-life indicators in gas mask filters, are more capable of increased sensitivity to volatile organic chemical vapors than porous silicon sensors alone. Compositional variations of the carbon layer within these composite materials have not been well studied. At low carbon content, the carbonized surface will not effectively mimic the active carbon used in gas mask filters. At high carbon content, there is increased noise and a broader, less intense rugate stop band, reducing the signal to noise level of the sensor response. The focus of this thesis is the optimization of the carbon layer in the carbon/porous silicon composite rugate filters. To accomplish this, porous silicon rugate filters were etched and then carbonized using varying concentrations of the poly(furfuryl alcohol) precursor. Variations in the carbon layer were then analyzed via spectral analysis, elemental analysis, and nitrogen adsorption/desorption isotherms. At concentrations greater than 50% furfuryl alcohol there is minimal difference observed in the carbon layer on the porous silicon surface. Samples were also shown to have a minimal increase in sensitivity at concentrations greater than 50% furfuryl alcohol, and an increased signal-to-noise with increased furfuryl alcohol concentration. It is shown that the optimal carbon layer for volatile organic vapor sensing is achieved by using a furfuryl alcohol concentration of 50% furfuryl alcohol (in ethanol) during carbon layer synthesis.

  1. Effect of the granulometric composition of lump coals on temperature distribution in a charge layer and at the bottom of a rotary furnace

    SciTech Connect

    Aksenov, L.N.; Aleksashin, V.N.; Makarov, G.N.; Pankratov, Yu.A.; Timofeev, Yu.D.; Khryukalov, A.A.

    1984-01-01

    The granulometric composition of a coal charge has considerable effect on the distribution of temperatures in a layer, and, consequently, on the degree of carbonization of the coke: the heating rate of a layer is decreased with an increase in the percentage of small classes; at the same time, the temperature-drop relative to height increases. The results obtained make it possible to adjust the coking period in a rotary furnace, taking into account the granulometric composition of the coal being coked.

  2. Long-Lasting Effects of Early-Life Antibiotic Treatment and Routine Animal Handling on Gut Microbiota Composition and Immune System in Pigs

    PubMed Central

    Schokker, Dirkjan; Zhang, Jing; Vastenhouw, Stéphanie A.; Heilig, Hans G. H. J.; Smidt, Hauke; Rebel, Johanna M. J.; Smits, Mari A.

    2015-01-01

    Background In intensive pig husbandry systems, antibiotics are frequently administrated during early life stages to prevent respiratory and gastro-intestinal tract infections, often in combination with stressful handlings. The immediate effects of these treatments on microbial colonization and immune development have been described recently. Here we studied whether the early life administration of antibiotics has long-lasting effects on the pig’s intestinal microbial community and on gut functionality. Methodology/Principal Findings To investigate the long-lasting effect of early-life treatment, piglets were divided into three different groups receiving the following treatments: 1) no antibiotics and no stress, 2) antibiotics and no stress, and 3) antibiotics and stress. All treatments were applied at day four after birth. Sampling of jejunal content for community scale microbiota analysis, and jejunal and ileal tissue for genome-wide transcription profiling, was performed at day 55 (~8 weeks) and day 176 (~25 weeks) after birth. Antibiotic treatment in combination with or without exposure to stress was found to have long-lasting effects on host intestinal gene expression involved in a multitude of processes, including immune related processes. Conclusions/Significance The results obtained in this study indicate that early life (day 4 after birth) perturbations have long-lasting effects on the gut system, both in gene expression (day 55) as well as on microbiota composition (day 176). At day 55 high variance was observed in the microbiota data, but no significant differences between treatment groups, which is most probably due to the newly acquired microbiota during and right after weaning (day 28). Based on the observed difference in gene expression at day 55, it is hypothesized that due to the difference in immune programming during early life, the systems respond differently to the post-weaning newly acquired microbiota. As a consequence, the gut systems of the treatment groups develop into different homeostasis. PMID:25658611

  3. Life History Traits and Niche Instability Impact Accuracy and Temporal Transferability for Historically Calibrated Distribution Models of North American Birds

    PubMed Central

    Wogan, Guinevere O. U.

    2016-01-01

    A primary assumption of environmental niche models (ENMs) is that models are both accurate and transferable across geography or time; however, recent work has shown that models may be accurate but not highly transferable. While some of this is due to modeling technique, individual species ecologies may also underlie this phenomenon. Life history traits certainly influence the accuracy of predictive ENMs, but their impact on model transferability is less understood. This study investigated how life history traits influence the predictive accuracy and transferability of ENMs using historically calibrated models for birds. In this study I used historical occurrence and climate data (1950-1990s) to build models for a sample of birds, and then projected them forward to the ‘future’ (1960-1990s). The models were then validated against models generated from occurrence data at that ‘future’ time. Internal and external validation metrics, as well as metrics assessing transferability, and Generalized Linear Models were used to identify life history traits that were significant predictors of accuracy and transferability. This study found that the predictive ability of ENMs differs with regard to life history characteristics such as range, migration, and habitat, and that the rarity versus commonness of a species affects the predicted stability and overlap and hence the transferability of projected models. Projected ENMs with both high accuracy and transferability scores, still sometimes suffered from over- or under- predicted species ranges. Life history traits certainly influenced the accuracy of predictive ENMs for birds, but while aspects of geographic range impact model transferability, the mechanisms underlying this are less understood. PMID:26959979

  4. Life History Traits and Niche Instability Impact Accuracy and Temporal Transferability for Historically Calibrated Distribution Models of North American Birds.

    PubMed

    Wogan, Guinevere O U

    2016-01-01

    A primary assumption of environmental niche models (ENMs) is that models are both accurate and transferable across geography or time; however, recent work has shown that models may be accurate but not highly transferable. While some of this is due to modeling technique, individual species ecologies may also underlie this phenomenon. Life history traits certainly influence the accuracy of predictive ENMs, but their impact on model transferability is less understood. This study investigated how life history traits influence the predictive accuracy and transferability of ENMs using historically calibrated models for birds. In this study I used historical occurrence and climate data (1950-1990s) to build models for a sample of birds, and then projected them forward to the 'future' (1960-1990s). The models were then validated against models generated from occurrence data at that 'future' time. Internal and external validation metrics, as well as metrics assessing transferability, and Generalized Linear Models were used to identify life history traits that were signific