Sample records for laminated diatom ooze

  1. Diatom Ooze: Ooze Clues

    NSDL National Science Digital Library

    Lisa Ayers Lawrence

    2014-04-08

    In this activity, learners will plot the distribution of various oozes using information from sediment maps. When skeletal remains of microscopic organisms make up more than 30% of the sediment, it is called "ooze." During this activity, learners will describe the characteristics of different types of seafloor sediments and oozes, predict the distribution of calcareous and siliceous oozes and compare and discuss locations of sediments and oozes.

  2. I. Grigorov et al. / Deep-Sea Research II 49 (2002) 33913407, DOI: 10.1016/S0967-0645(02)00089-9 Southern Ocean laminated diatom ooze: mat deposits and

    E-print Network

    Paris-Sud XI, Université de

    have been found in deep-sea settings in the eastern equatorial Pacific Ocean (Kemp and Baldauf, 1993I. Grigorov et al. / Deep-Sea Research II 49 (2002) 3391­3407, DOI: 10.1016/S0967-0645(02)00089-9 Southern Ocean laminated diatom ooze: mat deposits and potential for palaeo-flux studies, ODP leg 177, Site

  3. A rapidly deposited pennate diatom ooze in Upper Miocene-Lower Pliocene sediment beneath the North Pacific polar front

    USGS Publications Warehouse

    Dickens, G.R.; Barron, J.A.

    1997-01-01

    Rapidly deposited Thalassionema-Thalassiothrix pennate diatom oozes previously have been described in Upper Miocene-Lower Pliocene sediment beneath the frontal boundary of the eastern equatorial Pacific. Here we document a new occurrence of Thalassionema-Thalassiothrix ooze in Upper Miocene Lower Pliocene sediment beneath the frontal boundary of the subarctic North Pacific. The ooze is a 6 m interval of siliceous sediment at Ocean Drilling Program (ODP) sites 885/886 that was rapidly deposited between approximately 5.0 and 5.9 Ma. Bulk sediment in this interval may contain greater than 85% pennate diatom tests. There are also abundant laminae and pockets that are composed entirely of Thalassionema and Thalassiothrix diatoms. The presence of a rapidly deposited ooze dominated by pennate diatoms indicates unusual past conditions in the overlying surface waters. Time coincident deposition of such oozes at two distinct frontal boundary locations of the Pacific suggests that the unusual surface water conditions were causally linked to large-scale oceanographic change. This same oceanographic change most likely involved (1) addition of nutrients to the ocean, or (2) redistribution of nutrients within the ocean. The occurrence and origin of pennate diatom oozes may be a key component to an integrative understanding of late Neogene paleoceanography and biogeochemical cycling.

  4. Persisting maximum Agulhas leakage during MIS 14 indicated by massive Ethmodiscus oozes in the subtropical South Atlantic

    NASA Astrophysics Data System (ADS)

    Rackebrandt, Nick; Kuhnert, Henning; Groeneveld, Jeroen; Bickert, Torsten

    2011-09-01

    The glacial marine isotope stage 14 (MIS 14) appears in many climate records as an unusually warm glacial. During this period an almost monospecific, up to 1.5 m thick, laminated layer of the giant diatom Ethmodiscus rex has been deposited below the South Atlantic Subtropical Gyre. This oligotrophic region is today less favorable for diatom growth with sediments typically consisting of calcareous nannofossil oozes. We have reconstructed temperatures and the stable oxygen isotopic compositions of sea surface and thermocline water (?18Ow) from planktonic foraminiferal (Globigerinoides ruber and Globorotalia inflata) Mg/Ca and stable oxygen isotopes to test whether perturbations in surface ocean conditions contributed to the deposition of the diatom layer at 530 kyr B.P. Temperatures and ?18Ow values reconstructed from this diatom ooze interval are highly variable, with maxima similar to interglacial values. Since the area of the Ethmodiscus oozes resembles the region where Agulhas rings are present, we interpret these hydrographic changes to reflect the varying influence of warm and saline water of Indian Ocean origin that entered the Subtropical Gyre trapped in Agulhas rings. The formation of the Ethmodiscus oozes is associated with a period of maximum Agulhas leakage and a maximum frequency of Agulhas ring formation caused by a termination-type position of the Subtropical Front during the unusual warm MIS 14. The input of silica through the Agulhas rings enabled the shift in primary production from calcareous nannoplankton to diatoms, leading to the deposition of the massive diatom oozes.

  5. Microscopic observation of laminated sediment in thin section using diatom assemblages to reconstruct annual paleoenvironmental changes

    NASA Astrophysics Data System (ADS)

    Ishikawa, S.; Kaoru, K.

    2013-12-01

    Eastern Hokkaido is a severe earthquake and tsunami district. Lake Harutori, located in eastern Hokkaido, records 22 traces of huge tsunamis in lake sediment since 9500 years ago. The latest event was occurred in 17th century (e.g. Nanayama et al., 2003). However, the strict age is still unknown, because the autochthon Ainu culture did not have literature. In lake sediment, there is laminated structure between tsunami deposits, and also on the 17th huge tsunami deposit. If this laminated structure was recognized as annual varve, it will be able to decide the strict age and reconstruct the paleoenvironment in high resolution. Large thin section 165 mm length was made included 17th tsunami deposits, laminated silt layer and age known tephra and observed lithofacies and diatoms with 1,000 magnification light microscope. The thin section comprised from 80 mm thick tsunami deposit in bottom, 60 mm thick laminated silt layer, 15 mm tephra as known as Ta-b fallen in 1667A.D. and 10 mm laminated silt layer at the top. As the result of optical observation to laminated silt layer, 31 laminated structures were recognized. Inferred from diatom assemblages, 37 cyclic productions were recognized. Diatom components were apparently changed from bottom to top and were seemed to influence by the changes of lake water conditions after tsunami inundation. These results indicate that the start of accumulation of laminated silt layer and/or the end of confusion of lake water by tsunami current was around 1630 A.D.; 37 years before 1667 A.D.. This earthquake was separated from the 1611 Keicho Sanriku earthquake was well known in this era and the hypocenters of these earthquakes need to reexam.

  6. Choose Your Ooze

    NSDL National Science Digital Library

    2013-07-30

    During this activity, learners will make different versions of "ooze" using varied proportions of detergent and glue. Learners will observe, evaluate, and document different ooze properties by varying their recipes. Extensions provided on page 13. Part of the 21-activity guide published by OMSI, No Hassle Messy Science with a Wow. All activities in this guide use household materials and all lesson plans include preparation directions, demonstrations, procedure sheets, cross-curricular connections, and scientific explanation of content.

  7. Diatoms

    USGS Multimedia Gallery

    Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health....

  8. Diatoms

    USGS Multimedia Gallery

    Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. Diatoms can live in permanently ice-cove...

  9. Diatoms

    USGS Multimedia Gallery

    Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. Shown here is a live cell of Didymosphen...

  10. Diatoms

    USGS Multimedia Gallery

    Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. A large, living Pleurosira laevis cell h...

  11. Diatoms

    USGS Multimedia Gallery

    Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. A scanning electron micrograph (SEM) sho...

  12. Sediment indicators of meromixis: comparison of laminations, diatoms, and sediment chemistry in Brownie Lake, Minneapolis, USA

    Microsoft Academic Search

    B. Tracey; N. Lee; V. Card

    1996-01-01

    Meromixis has several powerful effects on lakes, yet there is no single definitive sediment indicator of meromixis. In this study three sediment indicators of meromixis were compared in Brownie Lake, Minneapolis, Minnesota, a small eutrophic lake that became meromictic around 1925. The results show that in Brownie the onset of laminations and changes in the iron to manganese ratio most

  13. Diatoms (Class Bacillariophyceae) and geochemistry from annually laminated mid-Holocene sediments, west coast Canada: insights into abrupt climate change in the past

    NASA Astrophysics Data System (ADS)

    Chang, A.; Pedersen, T. F.

    2009-04-01

    A 115-year record of annually laminated sediments from Effingham Inlet, a small anoxic fjord on the west coast of Vancouver Island, British Columbia (49?N, 125?W), was analyzed for diatoms (species and abundances) and geochemistry (C and N isotopes, organic C and trace elements Ag, Cd, Re and Mo) from a piston core. The sediments were radiocarbon dated at approx. 4200-4400 years before present (yr BP) and show diatom enriched varves in the lower 70 years, with a sudden transition to diatom impoverished varves above. In the lower section, varves are thick (2-5 mm) and consist of well-defined Thalassiosira-Skeletonema-Chaetoceros spring bloom successions. Diatom concentrations average at 787 733 million valves/g of dry sediment, del 15N at 7.0 0.5 per mil, and organic C at 5.2 0.5 wt. %. In the upper section, the varves are thinner (1-2 mm), do not clearly show the seasonal diatom succession, and contain increased terrigenous detritus. Diatom concentrations average at 388 202 million valves/g with an increased relative abundance of benthic and freshwater taxa, del 15N at 7.3 0.6 per mil and organic C at 5.7 0.5 wt. %. Values of del 13C for both sections are similar, averaging at -24.0 0.5 per mil. The trace element concentrations are quite variable throughout the section. However, several thin (<1 cm) nonlaminated intervals show decreased diatom abundances with concomitant increases in trace element concentrations, suggesting short-lived changes in surface productivity, upwelling and nutrient delivery, and/or anoxic conditions. The abrupt transition from diatom-rich to diatom-poor varves could reflect a shift in dominance of the North Pacific High and Aleutian Low atmospheric pressure systems over the northeast Pacific Ocean, not unlike the well-documented 1976/1977 climate regime shift which showed a change in upwelling and nutrient delivery. A transition between warm and sunny climates to cooler and wetter regimes at around 4000 yr BP has been noted in previous paleoenvironmental studies from British Columbia and the northern hemisphere in general. The Effingham Inlet sediment record data will also be compared with modern sediment trap data from the inlet.

  14. Late Quaternary Biosiliceous Laminated Marine Sediments From Antarctica: Seasonality During a Period of Rapid Climate Change

    NASA Astrophysics Data System (ADS)

    Pike, J.; Stickley, C. E.; Maddison, E. J.; Leventer, A.; Brachfeld, S.; Domack, E. W.; Dunbar, R. B.; Manley, P. L.; McClennen, C.

    2004-12-01

    The Antarctic ice sheet plays a key role in global oceanic and atmosphere systems. One of the most dynamic regions of the continent is the Antarctic Peninsula (AP) where ecological and cryospheric systems respond rapidly to climate change, such as the last deglaciation ( 12-13 kyr BP). Here, deglacial laminated diatom-rich marine sediments are well known, e.g., Palmer Deep (64 S 64 W; ODP Hole 1098A) comprising a distinctive 3 m thick sequence of deglacial `couplet' laminations. The East Antarctic margin (EAM), however, has received less attention than the West Antarctic margin (WAM) in palaeoceanographic studies yet its role in deep ocean circulation and, therefore, the global ocean system is significant. Recent sediment cores recovered from EAM sites during NSF Polar Programs-funded cruise NBP0101 in February and March 2001 (e.g. Mertz Drift \\{66 S 143 E\\}, Svenner Channel \\{69 S 77 E\\} in Prydz Bay, Nielsen Basin \\{67 S 66 E\\} and Iceberg Alley \\{67 S 63 E\\}), reveal that a similar sedimentary facies was deposited along the EAM, in similar geomorphological settings to Palmer Deep, during the same timeframe. These rich sediment archives reveal clues about circum-Antarctic palaeoceanographic change during the last deglaciation, a time of both high silica flux and rapid climate change. Microfabrics and diatom assemblages from scanning electron microscope backscattered and secondary electron imagery analysis of coeval deglacial varves from Palmer Deep (WAM), Mertz-Ninnis Trough and Iceberg Alley (EAM) are presented and compared. The varves from these localities are characterised by laminae to thin beds of orange-brown diatom ooze up to 8cm thick alternating with blue-grey diatom-bearing terrigenous sediments up to 4cm thick. The orange-brown oozes are dominated by resting spores and vegetative valves of Hyalochaete Chaetoceros spp., resulting from spring sedimentation associated with stratified surface waters promoting exceptionally high primary productivity. The blue-grey terrigenous sediments contain mixed open-water Antarctic diatoms resulting from summer/autumn sedimentation associated with increased terrigenous input and the annual trend to more oligotrophic conditions. The significance of these biogenic seasonal and annual cyclicities will be discussed in terms of interannual palaeoclimate oscillations. Sub-seasonality and a related deglacial trend are apparent within the spring lamine from the EAM and in the summer/autumn laminae from the WAM. This circum-Antarctic asymmetry indicates differences in the nature and timing of oceanographic and cryospheric systems operating around the Antarctic continent at this time.

  15. Experimental formation of chalk from calcareous ooze. Technical progress report

    SciTech Connect

    Seyfried, W.E.; Johnson, T.C.

    1981-02-15

    Samples of calcareous ooze collected from the tropical and equatorial Atlantic Ocean were subjected to hydrothermal alteration in order to simulate the diagenesis of chalk. Changes in mineralogy and morphology of enclosed microfossils were measured. (ACR)

  16. Invertebrate lamins

    SciTech Connect

    Melcer, Shai [Department of Genetics, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Gruenbaum, Yosef [Department of Genetics, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)]. E-mail: gru@vms.huji.ac.il; Krohne, Georg [Division of Electron Microscopy, Biocenter of the University Am Hubland, D-97074 Wuerzburg (Germany)]. E-mail: krohne@biozentrum.uni-wuerzburg.de

    2007-06-10

    Lamins are the main component of the nuclear lamina and considered to be the ancestors of all intermediate filament proteins. They are localized mainly at the nuclear periphery where they form protein complexes with integral proteins of the nuclear inner membrane, transcriptional regulators, histones and chromatin modifiers. Studying lamins in invertebrate species has unique advantages including the smaller number of lamin genes in the invertebrate genomes and powerful genetic analyses in Caenorhabditis elegans and Drosophila melanogaster. These simpler nuclear lamina systems allow direct analyses of their structure and functions. Here we give an overview of recent advances in the field of invertebrate nuclear lamins with special emphasis on their evolution, assembly and functions.

  17. The isotopic composition of diatom-bound nitrogen in Southern Ocean sediments

    NASA Astrophysics Data System (ADS)

    Sigman, Daniel M.; Altabet, Mark A.; Francois, Roger; McCorkle, Daniel C.; Gaillard, Jean-Francois

    1999-04-01

    Treatment of diatom microfossils from Southern Ocean sediments with hot perchloric acid leaves a "diatom-bound" N fraction which is 0-4 lower in ?15N than the bulk sediment, typically 3 lower in recent Antarctic diatom ooze. Results from Southern Ocean surface sediments indicate that early diagenetic changes in bulk sediment N content and ?15N are not reflected in diatom-bound N, suggesting that diatom-bound N is physically protected from early diagenesis by the microfossil matrix. A meridional transect of multicores from the Indian sector of the Southern Ocean shows a northward increase in the ?15N of diatom-bound N, suggesting that diatom-bound ?15N, like bulk sedimentary ?15N, varies with nitrate utilization in the overlying surface waters. The ?15N of diatom-bound N is 3-4 higher in glacial age Antarctic sediments than in Holocene sediments, supporting the hypothesis, previously based on bulk sediment ?15N, that nitrate utilization in the surface Antarctic was higher during the last ice age. While there are important uncertainties, the inferred range of utilization changes could potentially explain the entire 80 ppm amplitude of observed glacial/interglacial variations in atmospheric CO2.

  18. Laminate article

    DOEpatents

    Williams, Robert K. (Knoxville, TN); Paranthaman, Mariappan (Knoxville, TN); Chirayil, Thomas G. (Knoxville, TN); Lee, Dominic F. (Knoxville, TN); Goyal, Amit (Knoxville, TN); Feenstra, Roeland (Knoxville, TN)

    2002-01-01

    A laminate article comprises a substrate and a biaxially textured (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer over the substrate, wherein 0laminate article can include a layer of YBCO over the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  19. Diatoms (50 Species)

    USGS Multimedia Gallery

    Photomicrograph depicting the siliceous frustulesof fifty species of diatoms arranged within a circular shape. Diatoms form the base of many marine and aquatic food chains and upon death, their glassy frustules form sediments known as diatomaceous earth....

  20. Diatoms (50 Species)

    USGS Multimedia Gallery

    Photomicrograph depicting the siliceous frustules of fifty species of diatoms arranged within a circular shape. Diatoms form the base of many marine and aquatic food chains and upon death, their glassy frustules form sediments known as diatomaceous earth....

  1. Hybrid composite laminate structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Lark, R. F. (inventors)

    1977-01-01

    An invention which relates to laminate structures and specifically to essentially anisotropic fiber composite laminates is described. Metal foils are selectively disposed within the laminate to produce increased resistance to high velocity impact, fracture, surface erosion, and other stresses within the laminate.

  2. Stiffness design method of symmetric laminates using lamination parameters

    Microsoft Academic Search

    Hisao Fukunaga; Hideki Sekine

    1992-01-01

    A method is proposed for determining laminate configurations corresponding to the lamination parameters of a symmetric laminate whose in-plane and out-of-plane stiffness characteristics are governed by four in-plane and four out-of-plane lamination parameters, respectively. The relation between the lamination parameters is obtained, and the limitation of conventional laminates is discussed from the design viewpoint.

  3. Diatoms (50 Species)

    USGS Multimedia Gallery

    A photomicrograph depicting the siliceous frustules of fifty species of diatoms arranged within a circular shape. The image has been inverted to white on black to bring out details. Diatoms form the base of many marine and aquatic foodchains and upon death, their glassy frustules form sediments know...

  4. Diatomic Spectral Database

    National Institute of Standards and Technology Data Gateway

    SRD 114 Diatomic Spectral Database (Web, free access) All of the rotational spectral lines observed and reported in the open literature for 121 diatomic molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty, and reference are given for each transition reported.

  5. Lamination cooling system

    DOEpatents

    Rippel, Wally E.; Kobayashi, Daryl M.

    2005-10-11

    An electric motor, transformer or inductor having a lamination cooling system including a stack of laminations, each defining a plurality of apertures at least partially coincident with apertures of adjacent laminations. The apertures define a plurality of cooling-fluid passageways through the lamination stack, and gaps between the adjacent laminations are sealed to prevent a liquid cooling fluid in the passageways from escaping between the laminations. The gaps are sealed by injecting a heat-cured sealant into the passageways, expelling excess sealant, and heat-curing the lamination stack. The apertures of each lamination can be coincident with the same-sized apertures of adjacent laminations to form straight passageways, or they can vary in size, shape and/or position to form non-axial passageways, angled passageways, bidirectional passageways, and manifold sections of passageways that connect a plurality of different passageway sections. Manifold members adjoin opposite ends of the lamination stack, and each is configured with one or more cavities to act as a manifold to adjacent passageway ends. Complex manifold arrangements can create bidirectional flow in a variety of patterns.

  6. Reduction in bacterial ooze formation on immature fruitlets after preventive treatments of Fosethyl-Al against fire blight Erwinia amylovora.

    PubMed

    Deckers, T; Schoofs, H; Verjans, W; De Maeyer, L

    2010-01-01

    Fire blight, caused by the bacterium Erwinia amylovora (Burill Winslow et al.), is a very important bacterial disease on apple and pear orchards with devastating effects in some production area and in some years. Fire blight control consists in a whole strategy of measures that should start with control measures in and around the fruit tree nurseries. Only the use of Vacciplant (Laminarin), an inducer of the self-defence mechanism, is registered in Belgium since 2009. In other European countries Fosethyl-Al has been registered for fire blight control. Recently, research trials have been done at Pcfruit research station for several years on the activity of ALiette (fosethyl-Al) against fire blight. Fosethyl-Al, also a plant defence enhancing molecule, applied preventively 3 times at a dose of 3.75 kg/ha standard orchard (3 x 3000 g a.i./ha standard orchard), showed a reduction in the host susceptibility and decreased the disease development on artificial inoculated flower clusters and shoots. Also a clear reduction in the ooze droplet formation on artificially inoculated immature fruitlets has been observed with this molecule. This reduction in the bacterial ooze formation is considered as a very important factor in the spread of the disease in the orchard. PMID:21534464

  7. On Isotropic Laminate Configurations

    Microsoft Academic Search

    Hisao Fukunaga

    1990-01-01

    A particular class of laminated composites is presented where the stiffness characteristics are isotropic with respect to both in-plane and out-of-plane stiffnesses. The paper presents a determining method for isotropic and orthotropic laminate configurations and shows examples of isotropic laminates consisting of 40 plies. Experimental verifica tion by a tension test and a four-point flexure test has been made on

  8. Laminated reflective panels

    SciTech Connect

    Duchene, E.; Laroche, P.

    1985-04-16

    A laminated reflective panel comprises at least one mirror sheet which is less than 2.0 mm in thickness and which bears a reflective coating on its rear face. Each mirror sheet is laminated to a flat glass backing sheet which is thicker than the mirror sheet. The backing sheet is preferably of float glass.

  9. Laminated Pine Railway Sleepers

    Microsoft Academic Search

    G. S. Vermaak; P. Quinn

    1983-01-01

    This publication describes a series of tests designed and inspected by the South African Forestry Research Institute to determine the performance of laminated pine railway sleepers, crossing and bridging timbers installed in South African Railways lines over a period of 13 years. The results showed that laminated pine sleepers, properly impregnated with creosote, will have an average service life in

  10. Environmental investigations using diatom microfossils

    USGS Publications Warehouse

    Smith, Kathryn E.L.; Flocks, James G.

    2010-01-01

    Diatoms are unicellular phytoplankton (microscopic plant-like organisms) with cell walls made of silica (called a frustule). They live in both freshwater and saltwater and can be found in just about every place on Earth that is wet. The shape and morphology of the diatom frustule unique to each species are used for identification. Due to the microscopic size of diatoms, high-power microscopy is required for diatom identification. Diatoms are vital to life on Earth. They are photosynthetic primary producers, using sunlight to create oxygen and organic carbon from carbon dioxide and water. They are a significant source of the oxygen we breathe, have a major impact on the global carbon cycle (Smetacek, 1999), and are a food source for many aquatic organisms (Mann, 1993). Diatom abundance has even been demonstrated to have an influence on the diversity of larger marine mammals, including whales (Marx and Uhen, 2010). Data on diatom abundance and diversity are extremely useful in environmental studies.

  11. Fossil diatoms and neogene paleolimnology

    USGS Publications Warehouse

    Platt, Bradbury J.

    1988-01-01

    Diatoms have played an important role in the development of Neogene continental biostratigraphy and paleolimnology since the mid-19th Century. The history of progress in Quaternary diatom biostratigraphy has developed as a result of improved coring techniques that enable sampling sediments beneath existing lakes coupled with improved chronological control (including radiometric dating and varve enumeration), improved statistical treatment of fossil diatom assemblages (from qualitative description to influx calculations of diatom numbers or volumes), and improved ecological information about analogous living diatom associations. The last factor, diatom ecology, is the most critical in many ways, but progresses slowly. Fortunately, statistical comparison of modern diatom assemblages and insightful studies of the nutrient requirements of some common freshwater species are enabling diatom paleolimnologists to make more detailed interpretations of the Quaternary record than had been possible earlier, and progress in the field of diatom biology and ecology will continue to refine paleolimnological studies. The greater age and geologic setting of Tertiary diatomaceous deposits has prompted their study in the contexts of geologic history, biochronology and evolution. The distribution of diatoms of marine affinities in continental deposits has given geologists insights about tectonism and sea-level change, and the distribution of distinctive (extinct?) diatoms has found utilization both in making stratigraphic correlations between outcrops of diatomaceous deposits and in various types of biochronological studies that involve dating deposits in different areas. A continental diatom biochronologic scheme will rely upon evolution, such as the appearance of new genera within a family, in combination with regional environmental changes that are responsible for the wide distribution of distinctive diatom species. The increased use of the scanning electron microscope for the detailed descriptions of fossil diatoms will provide the basis for making more accurate correlations and identifications, and the micromorphological detail for speculations about evolutionary relationships. ?? 1988.

  12. A solution procedure for determining laminate configurations from lamination parameters

    Microsoft Academic Search

    Hisao Fukunaga

    1991-01-01

    The present paper shows a solution procedure for determining laminate configurations corresponding to in-plane and\\/or out-of-plane lamination parameters for symmetric and balanced laminates. The solution procedure is shown for the laminate with an infinite number of plies as well as that with a finite number of plies. As a numerical example of the present method, the laminate configurations with isotropic

  13. Flexible thermal laminate

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Sauers, D. G.

    1977-01-01

    Lightweight flexible laminate of interwoven conducting and insulating yarns, designed to provide localized controlled heating for propellant tanks on space vehicles, is useful for nonspace applications where weight, bulk, and flexibility are critical concerns.

  14. Lamination cooling system formation method

    DOEpatents

    Rippel, Wally E. (Altadena, CA); Kobayashi, Daryl M. (Monrovia, CA)

    2012-06-19

    An electric motor, transformer or inductor having a cooling system. A stack of laminations have apertures at least partially coincident with apertures of adjacent laminations. The apertures define straight or angled cooling-fluid passageways through the lamination stack. Gaps between the adjacent laminations are sealed by injecting a heat-cured sealant into the passageways, expelling excess sealant, and heat-curing the lamination stack. Manifold members adjoin opposite ends of the lamination stack, and each is configured with one or more cavities to act as a manifold to adjacent passageway ends. Complex manifold arrangements can create bidirectional flow in a variety of patterns.

  15. Lamination cooling system formation method

    DOEpatents

    Rippel, Wally E [Altadena, CA; Kobayashi, Daryl M [Monrovia, CA

    2009-05-12

    An electric motor, transformer or inductor having a cooling system. A stack of laminations have apertures at least partially coincident with apertures of adjacent laminations. The apertures define straight or angled cooling-fluid passageways through the lamination stack. Gaps between the adjacent laminations are sealed by injecting a heat-cured sealant into the passageways, expelling excess sealant, and heat-curing the lamination stack. Manifold members adjoin opposite ends of the lamination stack, and each is configured with one or more cavities to act as a manifold to adjacent passageway ends. Complex manifold arrangements can create bidirectional flow in a variety of patterns.

  16. Loosely-Bound Diatomic Molecules.

    ERIC Educational Resources Information Center

    Balfour, W. J.

    1979-01-01

    Discusses concept of covalent bonding as related to homonuclear diatomic molecules. Article draws attention to the existence of bound rare gas and alkaline earth diatomic molecules. Summarizes their molecular parameters and offers spectroscopic data. Strength and variation with distance of interatomic attractive forces is given. (Author/SA)

  17. Interactions between Diatoms and Bacteria

    PubMed Central

    Amin, Shady A.; Parker, Micaela S.

    2012-01-01

    Summary: Diatoms and bacteria have cooccurred in common habitats for hundreds of millions of years, thus fostering specific associations and interactions with global biogeochemical consequences. Diatoms are responsible for one-fifth of the photosynthesis on Earth, while bacteria remineralize a large portion of this fixed carbon in the oceans. Through their coexistence, diatoms and bacteria cycle nutrients between oxidized and reduced states, impacting bioavailability and ultimately feeding higher trophic levels. Here we present an overview of how diatoms and bacteria interact and the implications of these interactions. We emphasize that heterotrophic bacteria in the oceans that are consistently associated with diatoms are confined to two phyla. These consistent bacterial associations result from encounter mechanisms that occur within a microscale environment surrounding a diatom cell. We review signaling mechanisms that occur in this microenvironment to pave the way for specific interactions. Finally, we discuss known interactions between diatoms and bacteria and exciting new directions and research opportunities in this field. Throughout the review, we emphasize new technological advances that will help in the discovery of new interactions. Deciphering the languages of diatoms and bacteria and how they interact will inform our understanding of the role these organisms have in shaping the ocean and how these interactions may change in future oceans. PMID:22933565

  18. Diatomic gasdynamic lasers.

    NASA Technical Reports Server (NTRS)

    Mckenzie, R. L.

    1972-01-01

    Predictions from a numerical model of the vibrational relaxation of anharmonic diatomic oscillators in supersonic expansions are used to show the extent to which the small anharmonicity of gases like CO can cause significant overpopulations of upper vibrational states. When mixtures of CO and N2 are considered, radiative gain on many of the vibration-rotation transitions of CO is predicted. Experiments are described that qualitatively verify the predictions by demonstrating laser oscillation in CO-N2 expansions. The resulting CO-N2 gasdynamic laser displays performance characteristics that equal or exceed those of similar CO2 lasers.

  19. Diatomic gasdynamic lasers

    NASA Technical Reports Server (NTRS)

    Mckenzie, R. L.

    1971-01-01

    Predictions from a numerical model of the vibrational relaxation of anharmonic diatomic oscillators in supersonic expansions are used to show the extent to which the small anharmonicity of gases like CO can cause significant overpopulations of upper vibrational states. When mixtures of CO and N2 are considered, radiative gain on many of the vibration-rotation transitions of CO is predicted. Experiments are described that qualitatively verify the predictions by demonstrating laser oscillation in CO-N2 expansions. The resulting CO-N2 gasdynamic laser displays performance characteristics that equal or exceed those of similar CO2 lasers.

  20. Diatomic predissociation line widths

    NASA Technical Reports Server (NTRS)

    Child, M. S.

    1973-01-01

    Predissociation by rotation and curve crossing in diatomic molecules is discussed. The pattern of predissociation line widths is seen as providing a highly sensitive yardstick for the determination of unknown potential curves. In addition, the computation of such a pattern for given potential curves is considered a matter of routine, unless the predissociation happens to occur from an adiabatic potential curve. Analytic formulas are used to provide physical insight into the details of the predissociation pattern, to the extent that a direct inversion procedure is developed for determination of the repulsive potential curves for Type 1 predissociations.

  1. Resin hybrid composite laminates

    SciTech Connect

    Bhatnagar, A.

    1986-01-01

    Hybrid composites are generally referred to as the materials that combine two or more fibers in a suitable binding resin. Resin hybrid composites described in this paper utilize two or more resins with a suitable reinforcement. The resins are rigid resin and flexible resins. The elongation of the rigid resin is less than 2% and elongation of the flexible resins are varied between 25% to 100% by blending a very flexible resin with the rigid resin. Test laminates are fabricated by using either glass, carbon or aramid reinforcement in a layered sequence. This produces rigid-flexible-rigid and flexible-rigid-flexible laminates. These laminates are tested for impact, compression, flexural and inter-laminar strengths. Results show that the resin hybriding provides a wide choice of mechanical properties to the composite industry.

  2. Laminate armor and related methods

    DOEpatents

    Chu, Henry S; Lillo, Thomas M; Zagula, Thomas M

    2013-02-26

    Laminate armor and methods of manufacturing laminate armor. Specifically, laminate armor plates comprising a commercially pure titanium layer and a titanium alloy layer bonded to the commercially pure titanium outer layer are disclosed, wherein an average thickness of the titanium alloy inner layer is about four times an average thickness of the commercially pure titanium outer layer. In use, the titanium alloy layer is positioned facing an area to be protected. Additionally, roll-bonding methods for manufacturing laminate armor plates are disclosed.

  3. Late Quaternary Biosiliceous Laminated Marine Sediments From Antarctica: Seasonality During a Period of Rapid Climate Change

    Microsoft Academic Search

    J. Pike; C. E. Stickley; E. J. Maddison; A. Leventer; S. Brachfeld; E. W. Domack; R. B. Dunbar; P. L. Manley; C. McClennen

    2004-01-01

    The Antarctic ice sheet plays a key role in global oceanic and atmosphere systems. One of the most dynamic regions of the continent is the Antarctic Peninsula (AP) where ecological and cryospheric systems respond rapidly to climate change, such as the last deglaciation ( 12-13 kyr BP). Here, deglacial laminated diatom-rich marine sediments are well known, e.g., Palmer Deep (64

  4. Lamination and laminated rhythmites in water-laid sands

    Microsoft Academic Search

    Hans-Erich Reineck; Friedrich Wunderlich

    1998-01-01

    Laminated sand and laminated rhythmites are produced by a variety of physical processes and are hence known from several specific\\u000a environments in association with a variety of structures and textures.\\u000a \\u000a Laminated sands associated with plane bed phases of the upper flow regime are mostly produced in shallow water environments\\u000a like rivers, ephemeral streams, tidal flats, channels and gullies, but have

  5. Laminated piezoelectric transformer

    NASA Technical Reports Server (NTRS)

    Vazquez Carazo, Alfredo (Inventor)

    2006-01-01

    A laminated piezoelectric transformer is provided using the longitudinal vibration modes for step-up voltage conversion applications. The input portions are polarized to deform in a longitudinal plane and are bonded to an output portion. The deformation of the input portions is mechanically coupled to the output portion, which deforms in the same longitudinal direction relative to the input portion. The output portion is polarized in the thickness direction relative its electrodes, and piezoelectrically generates a stepped-up output voltage.

  6. Solar cell module lamination process

    DOEpatents

    Carey, Paul G. (Mountain View, CA); Thompson, Jesse B. (Brentwood, CA); Aceves, Randy C. (Tracy, CA)

    2002-01-01

    A solar cell module lamination process using fluoropolymers to provide protection from adverse environmental conditions and thus enable more extended use of solar cells, particularly in space applications. A laminate of fluoropolymer material provides a hermetically sealed solar cell module structure that is flexible and very durable. The laminate is virtually chemically inert, highly transmissive in the visible spectrum, dimensionally stable at temperatures up to about 200.degree. C. highly abrasion resistant, and exhibits very little ultra-violet degradation.

  7. Diatom genomics: genetic acquisitions and mergers.

    PubMed

    Nisbet, R Ellen R; Kilian, Oliver; McFadden, Geoffrey I

    2004-12-29

    Diatom algae arose by two-step endosymbiosis. The complete genome of the diatom Thalassiosira pseudonana has now been sequenced, allowing us to reconstruct the remarkable intracellular gene transfers that occurred during this convoluted cellular evolution. PMID:15620637

  8. Thermal conductivity of graphene laminate.

    PubMed

    Malekpour, H; Chang, K-H; Chen, J-C; Lu, C-Y; Nika, D L; Novoselov, K S; Balandin, A A

    2014-09-10

    We have investigated thermal conductivity of graphene laminate films deposited on polyethylene terephthalate substrates. Two types of graphene laminate were studied, as deposited and compressed, in order to determine the physical parameters affecting the heat conduction the most. The measurements were performed using the optothermal Raman technique and a set of suspended samples with the graphene laminate thickness from 9 to 44 ?m. The thermal conductivity of graphene laminate was found to be in the range from 40 to 90 W/mK at room temperature. It was found unexpectedly that the average size and the alignment of graphene flakes are more important parameters defining the heat conduction than the mass density of the graphene laminate. The thermal conductivity scales up linearly with the average graphene flake size in both uncompressed and compressed laminates. The compressed laminates have higher thermal conductivity for the same average flake size owing to better flake alignment. Coating plastic materials with thin graphene laminate films that have up to 600 higher thermal conductivity than plastics may have important practical implications. PMID:25111490

  9. Beach lamination: Nature and origin

    USGS Publications Warehouse

    Clifton, H.E.

    1969-01-01

    A distinctive two-fold sedimentation unit characterizes lamination in the upper swash zone of beaches. Within the unit a fine and/or a heavy mineral rich layer at the base grades upward into a coarser and/or a heavy mineral poor layer at the top. This distinctive type of lamination results from grain segregation within bed flow during wave backwash. ?? 1969.

  10. Holographic nondestructive testing of laminates

    NASA Technical Reports Server (NTRS)

    Stuckenberg, F. H.

    1973-01-01

    Very small differences in laminate thickness result in interference fringes in holograph image. These indicate presence of unbonded area. Theoretical knowledge of membrane deflection may be used in conjunction with reduced number of pretest experiments to determine number of optical fringes that should appear for given laminate.

  11. Diatom Genomics: Genetic Acquisitions and Mergers

    E-print Network

    McFadden, Geoff

    Diatom Genomics: Genetic Acquisitions and Mergers Dispatch R. Ellen R. Nisbet, Oliver Kilian and Geoffrey I. McFadden Diatom algae arose by two-step endosymbiosis. The complete genome of the diatom. They comman- deer your intellectual property, relocate it to head office, and -- to add insult to injury

  12. Experimental Studies on Sexual Reproduction in Diatoms

    Microsoft Academic Search

    Victor A. Chepurnov; David G. Mann; Koen Sabbe; Wim Vyverman

    2004-01-01

    The diatoms are the most speciose group of algae, having global ecological significance in the carbon and silicon cycles. They are almost unique among algae in being diplontic, and sexual reproduction is an obligate stage in the life cycle of most diatom species. It is unclear which are the principal factors that have fostered the evolutionary success of diatoms, but

  13. Diatom 'Didymosphenia geminata' Cell Wall

    USGS Multimedia Gallery

    Image of the silica cell wall of the diatom 'Didymosphenia geminata' from Rio Espolon, Chile. The sample was collected early in 2010 from an extensive bloom on the river. The image has been processed to show the silica cell wall, removing the organic cell contents and the stalk material....

  14. Dead Diatoms Do Tell Tales

    NSDL National Science Digital Library

    LuAnn Dahlman

    This activity engages learners to make a model of sediment cores using different kinds of glass beads and sand. They learn how to examine the types, numbers, and conditions of diatom skeletons in the model sediment cores and tell something about the hypothetical paleoclimate that existed when they were deposited. The students get to be climate detectives.

  15. Hierarchic models for laminated composites

    NASA Technical Reports Server (NTRS)

    Babuska, Ivo; Szabo, Barna A.; Actis, Ricardo L.

    1992-01-01

    The principles governing the formulation of hierarchic models for laminated composites are discussed. The essential features of the hierarchic models described herein are: (1) the exact solutions corresponding to the hierarchic sequence of models converge to the exact solution of the corresponding problem of elasticity for a fixed laminate thickness; and (2) the exact solution of each model converges to the same limit as the exact solution of the corresponding problem of elasticity with respect to the laminate thickness approaching zero. Hierarchic models make the computation of any engineering data possible to an arbitrary level of precision within the framework of the theory of elasticity.

  16. High diatom production and export in stratified waters - A potential negative feedback to global warming

    NASA Astrophysics Data System (ADS)

    Kemp, Alan E. S.; Villareal, Tracy A.

    2013-12-01

    It is widely held that increased stratification and reduced vertical mixing in the ocean driven by global warming will promote the replacement of diatoms by smaller phytoplankton and lead to an overall decrease in productivity and carbon export. Here we present contrary evidence from a synergy of modern observations and palaeo-records that reveal high diatom production and export from stratified waters. Diatom adaptations to stratified waters include the ability to grow in low light conditions in deep chlorophyll maxima; vertical migrations between nutricline depths and the surface, and symbioses with N2-fixing cyanobacteria in diatom-diazotroph associations (DDA). These strategies foster the maintenance of seed populations that may then exploit mixing events induced by storms or eddies, but may also inherently promote blooms. Recent oceanographic observations in the subtropical gyres, at increasingly high temporal and spatial resolutions, have monitored short-lived but often substantial blooms and export of stratified-adapted diatoms including rhizosolenids and the diazotroph-associated Hemiaulus hauckii. Aggregate formation by such diatoms is common and promotes rapid settling thereby minimizing water column remineralization and optimizing carbon flux. Convergence zones associated with oceanic fronts or mesoscale features may also generate substantial flux of stratified-adapted diatom species. Conventional oceanographic observing strategies and sampling techniques under-represent such activity due to the lack of adequate capability to sample the large sized diatoms and colonies involved, the subsurface location of many of these blooms, their common development in thin <3 m layers and their episodic nature. Superbly preserved palaeo-sediment trap records in laminated sediments reveal enhanced production and export from stratified waters mediated by the same taxa. The organic carbon-rich Mediterranean sapropels were the result of production within deep chlorophyll maxima in highly stratified waters dominated by rhizosolenid diatoms but also including H. hauckii. In the Cretaceous when CO2 levels were higher than present, laminated sediments reveal dominant flux also including Hemiaulus and rhizosolenid species. Nitrogen isotope and biomarker studies suggest that, analogous to modern DDA blooms within the subtropical gyres, Hemiaulus blooms in the ancient Mediterranean and within the Cretaceous seas were aided by nitrogen-fixing cyanobacterial symbionts. These lines of evidence suggest that diatom production and associated export of organic carbon, may not decrease, as is widely predicted, but may actually increase with greater ocean stratification, and potentially act as a negative feedback to global warming. However, the key genera involved in such potential feedbacks are underrepresented in both laboratory and field studies and are poorly represented in models. Our findings suggest that a reappraisal is necessary of the way diatoms are represented as plankton functional types (PFTs) in ocean biogeochemical models and that new observing and sampling strategies are also required to study these processes.

  17. Risk factors for equine laminitis

    E-print Network

    Polzer, John Patrick

    1995-01-01

    logistic regression to assess age, breed, sex, and seasonality as risk factors for equine laminitis. There were 70 acute cases, 183 chronic cases, and 779 controls. No statistical association was found between age, breed, sex, or seasonality...

  18. Sudden bending of cracked laminates

    NASA Technical Reports Server (NTRS)

    Sih, G. C.; Chen, E. P.

    1980-01-01

    A dynamic approximate laminated plate theory is developed with emphasis placed on obtaining effective solution for the crack configuration where the 1/square root of r stress singularity and the condition of plane strain are preserved. The radial distance r is measured from the crack edge. The results obtained show that the crack moment intensity tends to decrease as the crack length to laminate plate thickness is increased. Hence, a laminated plate has the desirable feature of stabilizing a through crack as it increases its length at constant load. Also, the level of the average load intensity transmitted to a through crack can be reduced by making the inner layers to be stiffer than the outer layers. The present theory, although approximate, is useful for analyzing laminate failure to crack propagation under dynamic load conditions.

  19. Hierarchic models for laminated plates

    NASA Technical Reports Server (NTRS)

    Szabo, Barna A.; Actis, Ricardo L.

    1991-01-01

    The research conducted in the formulation of hierarchic models for laminated plates is described. The work is an extension of the work done for laminated strips. The use of a single parameter, beta, is investigated that represents the degree to which the equilibrium equations of three dimensional elasticity are satisfied. The powers of beta identify members in the hierarchic sequence. Numerical examples that were analyzed with the proposed sequence of models are included. The results obtained for square plates with uniform loading and homogeneous boundary conditions are very encouraging. Several cross-ply and angle-ply laminates were evaluated and the results compared with those of the fully three dimensional model, computed using MSC/PROBE, and with previously reported work on laminated strips.

  20. Vacuum lamination of photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Burger, D. R.

    1982-01-01

    Vacuum lamination of terrestrial photovoltaic modules is a new high volume process requiring new equipment and newly develop materials. Equipment development, materials research, and some research in related fields and testing methods are discussed.

  1. Laminated electromagnetic pump stator core

    DOEpatents

    Fanning, Alan W. (San Jose, CA)

    1995-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference.

  2. Laminated electromagnetic pump stator core

    DOEpatents

    Fanning, A.W.

    1995-08-08

    A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference. This pump is used in nuclear fission reactors. 19 figs.

  3. Push Tester For Laminated Films

    NASA Technical Reports Server (NTRS)

    Sugimura, Russell S.

    1991-01-01

    Small instrument used to measure brittleness of polymer film adhesively bonded to hard substrate. Penlike instrument has microball tip. Small pointer in slot on side of instrument used to calibrate and indicate spring force applied by point. Microball dents only small area of specimen. Such measurements used to measure rates of embrittlement in environmental tests of candidate laminated-film covers for photovoltaic modules. Not limited to transparent films; also used on opaque laminated films on back panels of photovoltaic modules.

  4. DIATOMS: One-Celled Wonders

    NSDL National Science Digital Library

    Linda Allison

    2006-01-01

    Diatoms (DIE-a-toms) are one of the most important things you never knew about. They are everywhere there is water. A drop of lake water is packed with them. You probably swallow millions every time you go swimming. These tiny, one-celled life forms populate the world's ponds, rivers, and oceans (and anywhere else that's the least bit wet). They spend their invisible lives quietly using sunlight to turn carbon dioxide and water into food and oxygen. Diatoms are the basis of the food chain, and they produce much of the oxygen you breathe. This free selection about this one-celled wonder includes Part I of a sample activity from the book.

  5. Milking Diatoms for Sustainable Energy: Biochemical Engineering versus Gasoline-Secreting Diatom Solar Panels

    Microsoft Academic Search

    T. V. Ramachandra; Durga Madhab Mahapatra; Karthick B; Richard Gordon

    2009-01-01

    In the face of increasing CO2 emissions from conventional energy (gasoline), and the anticipated scarcity of crude oil, a worldwide effort is underway for cost-effective renewable alternative energy sources. Here, we review a simple line of reasoning: (a) geologists claim that much crude oil comes from diatoms; (b) diatoms do indeed make oil; (c) agriculturists claim that diatoms could make

  6. Diatom Paleolimnology Data Cooperative Home Page

    NSDL National Science Digital Library

    The Phycology Section of the Patrick Center for Environmental Research, part of Philadelphia's Academy of Natural Science, presents the Diatom Paleolimnology Data Cooperative (DPDC). This database contains information on diatoms and related ecological and paleolimnological data applicable to the study of global climate change. Users have three search options: browse and download stratigraphic and calibration data sets; view individual diatom counts; or search for occurrences of specific taxa in all data sets. The site includes links to algae databases, also from the Academy of Natural Science. Researchers are encouraged to submit diatom core and surface sediment data to the DPDC.

  7. Diatom-inspired templates for 3D replication: natural diatoms versus laser written artificial diatoms.

    PubMed

    Belegratis, M R; Schmidt, V; Nees, D; Stadlober, B; Hartmann, P

    2014-03-01

    The diatoms are ubiquitous, exist in large numbers and show a great diversity of features on their porous silica structures. Therefore, they inspire the fabrication of nanostructured templates for nanoimprint processes (NIL), where large structured areas with nanometer precision are required. In this study, two approaches regarding the respective challenges and potential exploitations are followed and discussed: the first one takes advantage of a template that is directly made of natural occurring diatoms. Here, two replication steps via soft lithography are needed to obtain a template which is subsequently used for NIL. The second approach exploits the technical capabilities of the precise 3D laser lithography (3DLL) based on two-photon polymerization of organic materials. This method enables the fabrication of arbitrary artificial diatom-inspired micro- and nanostructures and the design of an inverse structure. Therefore, only one replication step is needed to obtain a template for NIL. In both approaches, a replication technique for true 3D structures is shown. PMID:24343246

  8. Interphase phosphorylation of lamin A.

    PubMed

    Kochin, Vitaly; Shimi, Takeshi; Torvaldson, Elin; Adam, Stephen A; Goldman, Anne; Pack, Chan-Gi; Melo-Cardenas, Johanna; Imanishi, Susumu Y; Goldman, Robert D; Eriksson, John E

    2014-06-15

    Nuclear lamins form the major structural elements that comprise the nuclear lamina. Loss of nuclear structural integrity has been implicated as a key factor in the lamin A/C gene mutations that cause laminopathies, whereas the normal regulation of lamin A assembly and organization in interphase cells is still undefined. We assumed phosphorylation to be a major determinant, identifying 20 prime interphase phosphorylation sites, of which eight were high-turnover sites. We examined the roles of these latter sites by site-directed mutagenesis, followed by detailed microscopic analysis - including fluorescence recovery after photobleaching, fluorescence correlation spectroscopy and nuclear extraction techniques. The results reveal three phosphorylation regions, each with dominant sites, together controlling lamin A structure and dynamics. Interestingly, two of these interphase sites are hyper-phosphorylated in mitotic cells and one of these sites is within the sequence that is missing in progerin of the Hutchinson-Gilford progeria syndrome. We present a model where different phosphorylation combinations yield markedly different effects on the assembly, subunit turnover and the mobility of lamin A between, and within, the lamina, the nucleoplasm and the cytoplasm of interphase cells. PMID:24741066

  9. Lamin A, farnesylation and aging

    SciTech Connect

    Reddy, Sita [Department of Biochemistry and Molecular Biology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 (United States)] [Department of Biochemistry and Molecular Biology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 (United States); Comai, Lucio, E-mail: comai@usc.edu [Department of Molecular Microbiology and Immunology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 (United States)] [Department of Molecular Microbiology and Immunology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 (United States)

    2012-01-01

    Lamin A is a component of the nuclear envelope that is synthesized as a precursor prelamin A molecule and then processed into mature lamin A through sequential steps of posttranslational modifications and proteolytic cleavages. Remarkably, over 400 distinct point mutations have been so far identified throughout the LMNA gene, which result in the development of at least ten distinct human disorders, collectively known as laminopathies, among which is the premature aging disease Hutchinson-Gilford progeria syndrome (HGPS). The majority of HGPS cases are associated with a single point mutation in the LMNA gene that causes the production of a permanently farnesylated mutant lamin A protein termed progerin. The mechanism by which progerin leads to premature aging and the classical HGPS disease phenotype as well as the relationship between this disorder and the onset of analogous symptoms during the lifespan of a normal individual are not well understood. Yet, recent studies have provided critical insights on the cellular processes that are affected by accumulation of progerin and have suggested that cellular alterations in the lamin A processing pathway leading to the accumulation of farnesylated prelamin A intermediates may play a role in the aging process in the general population. In this review we provide a short background on lamin A and its maturation pathway and discuss the current knowledge of how progerin or alterations in the prelamin A processing pathway are thought to influence cell function and contribute to human aging.

  10. Diatom biomineralization reflected in diatom B/Si

    NASA Astrophysics Data System (ADS)

    Stoll, H.; Mejia-Ramirez, L. M.; Isensee, K.; Mendez-Vicente, A.; Pisonero, J.

    2012-04-01

    Because boron speciation in seawater is controlled by pH there has been wide interest in using the concentration and isotopic composition of B in marine biominerals to reconstruct past changes in ocean pH. Biomineralization may modulate B incorporation either through cellular pH regulation or uptake processes. We investigate the effect of biomineralization on B incorporation in opal from diatoms. Two species of diatoms, Thalassiosira weissflogii and T. pseudonana, were cultured at pH between 7.4 and 8.6, equivalent to pCO2 from 2000 to 200 ppmv. Growth rate, type of carbon acquisition, and silicon and carbon quotas were determined. Harvested opal was thoroughly cleaned of organic matter using permanganate and perchloric acid oxidative treatments. The boron content of opal was determined by mounting cleaned frustules in epoxy resin for measurement of 11B and 28Si on LA-ICPMS (Resonetics, Agilent 7700 ). LA-ICPMS measurements are reproducible from one session to the next and indicate B concentrations in T. pseudonana ranging from 7 to 40 ppm and in T. weissflogii from 4 to 9 ppm. B content in T. pseudonana is correlated with bicarbonate uptake rate and with normalized Si quotas, while for T. weissflogii, which is a bicarbonate-restricted user at the pH studied, B content seems to be regulated primarily by the borate/bicarbonate seawater ratio. We present a simple cellular model of B and Si uptake by diatoms to quantitatively explore the mechanisms for variable B content and its potential as a proxy .

  11. Basic mechanics of laminated composite plates

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    1994-01-01

    The mechanics of laminated composite materials is presented in a clear manner with only essential derivations included. The constitutive equations in all of their forms are developed and then summarized in a separate section. The effects of hygrothermal effects are included. The prediction of the engineering constants for a laminate are derived. Strength of laminated composites is not covered.

  12. Performance of laminated ceramic composite cutting tools

    Microsoft Academic Search

    Maurice F. Amateau; Bruce Stutzman; Joseph C. Conway; Joseph Halloran

    1995-01-01

    Laminated ceramic composite cutting tools have been developed which demonstrate improvements in strength, toughness, and thermal shock resistance compared to the conventional non-laminated ceramic composites. Silicon carbide whisker and titanium carbide particulate reinforced ceramic matrix composites have been designed as multilayer structures and fabricated into cutting tool inserts for evaluation in machining tests. Laminated ceramic composite designs exhibited significantly better

  13. Almost filling laminations and the connectivity of ending lamination space

    Microsoft Academic Search

    David Gabai

    2009-01-01

    We show that if S is a finite type orientable surface of negative Euler\\u000acharacteristic which is not the 3-holed sphere, 4-holed sphere or 1-holed\\u000atorus, then the ending lamination space of S is connected, locally path\\u000aconnected and cyclic.

  14. Steady state response of unsymmetrically laminated plates

    SciTech Connect

    Hosokawa, Kenji; Kawashima, Katsuya; Sakata, Toshiyuki [Chubu Univ., Kasugai, Aichi (Japan). Dept. of Mechanical Engineering

    1995-11-01

    A numerical approach for analyzing the forced vibration problem of a symmetrically laminated FRP (fiber reinforced plastic) composite plate was proposed by the authors. In the present paper, this approach is modified for application to an unsymmetrically laminated FRP composite plate. Numerical calculations are carried out for the clamped antisymmetrically laminated rectangular and elliptical plates which are a kind of unsymmetrically laminated plate. Then,, the effects of the lamina material and the fiber orientation angle on the steady state response are discussed. Furthermore, it is investigated that what structural damping factor is most influenced on the steady state response of an antisymmetrically laminated plate.

  15. Dimensional control of polymer composite laminate

    NASA Astrophysics Data System (ADS)

    Chen, Ming-Yang; Chen, Shih-Ming; Zeng, Long-Zeng; Chen, Jong-Pyng

    1992-05-01

    In order to manufacture high quality composites, the dimensional control of composite laminate is required. Composite laminate dimension is greatly affected by curing processing parameters such as applied pressure, heat-up rate, bleeder quantities, and temperature. This paper investigates the dimensional stability of a C/E composite laminate under autoclave curing conditions by using the economical and highly reproducible Taguchi Method. The optimum curing conditions for stabilizing the laminate thickness were obtained from dynamic characteristic analysis. An equation accurately predicting the laminate thickness was postulated after analyzing the experimental data with the statistical method.

  16. The Phaeodactylum genome reveals the evolutionary history of diatom genomes

    Microsoft Academic Search

    Chris Bowler; Jonathan H. Badger; Jane Grimwood; Kamel Jabbari; Alan Kuo; Uma Maheswari; Cindy Martens; Florian Maumus; Robert P. Otillar; Edda Rayko; Asaf Salamov; Klaas Vandepoele; Bank Beszteri; Ansgar Gruber; Marc Heijde; Michael Katinka; Thomas Mock; Klaus Valentin; Frderic Verret; John A. Berges; Colin Brownlee; Jean-Paul Cadoret; Anthony Chiovitti; Chang Jae Choi; Sacha Coesel; Alessandra de Martino; J. Chris Detter; Colleen Durkin; Angela Falciatore; Jrome Fournet; Miyoshi Haruta; Marie J. J. Huysman; Bethany D. Jenkins; Katerina Jiroutova; Richard E. Jorgensen; Yolaine Joubert; Aaron Kaplan; Nils Krger; Peter G. Kroth; Julie La Roche; Erica Lindquist; Markus Lommer; Vronique Martin-Jzquel; Pascal J. Lopez; Susan Lucas; Manuela Mangogna; Karen McGinnis; Linda K. Medlin; Anton Montsant; Marie-Pierre Oudot-Le Secq; Carolyn Napoli; Miroslav Obornik; Micaela Schnitzler Parker; Jean-Louis Petit; Betina M. Porcel; Nicole Poulsen; Matthew Robison; Leszek Rychlewski; Tatiana A. Rynearson; Jeremy Schmutz; Harris Shapiro; Magali Siaut; Michele Stanley; Michael R. Sussman; Alison R. Taylor; Assaf Vardi; Peter von Dassow; Wim Vyverman; Anusuya Willis; Lucjan S. Wyrwicz; Daniel S. Rokhsar; Jean Weissenbach; E. Virginia Armbrust; Beverley R. Green; Yves van de Peer; Igor V. Grigoriev

    2008-01-01

    Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one-fifth of the primary productivity on Earth. The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology. Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum

  17. Synthesis and characterization of diatom inspired nanocomposites

    NASA Astrophysics Data System (ADS)

    Gutu, Timothy

    This dissertation addresses the investigation of two novel methods to synthesize composite nanomaterials inspired by marine microalgae called diatoms. Diatoms are inspirational sources of silica structures, ordered at micro- to nanoscale, that possess unique optical properties. The fabrication of nanomaterials with well-defined and controllable micro-to nanoscale features has been of great interest for chemical, optical, electronic, catalytic, environmental, and medical applications. While bottom-up and top-down approaches have been extensively used to fabricate two-dimensional structures and devices, there is a need for inexpensive methods to mass-produce complex micro- to nanoscale structures with a variety of three-dimensional (3D) morphologies at high degrees of precision, reproducibility, and chemical tailorability. To explore the fabrication of 3D nanostructures, this study harnessed the biomineralization capacity of diatom cell cultures to fabricate Si-Ge oxide nanocomposites on one hand and the chemical bath deposition on the other hand. A two-stage photobioreactor strategy was used to metabolically insert nanostructured germanium into the silica microstructure of diatom of diatom Pinnularia sp. In the first stage, diatom cells were grown to the point of silicon starvation. In the second stage, a pulse of silicon and germanium solution was added to the silicon-starved cells. Various electron microscopy techniques were utilized to validate the extent of the insertion and the subsequent incorporation of germanium into the diatom silica matrix. In the second method to form diatom inspired nanocomposites, we utilize a simple, inexpensive chemical bath deposition technique to deposit a cadmium sulfide nanocrystals on the patterned surface of diatom biosilica. A parametric investigation of the factors affecting the chemical bath process was carried out. The morphology, structural and compositional properties of the composites were characterized by electron microscopy. Absorption spectroscopy, photoluminescence and Raman spectroscopy were used to study the properties of the deposited CdS thin films.

  18. A computational procedure to analyze metal matrix laminates with nonlinear lamination residual strains

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sullivan, T. L.

    1974-01-01

    An approximate computational procedure is described for the analysis of angleplied laminates with residual nonlinear strains. The procedure consists of a combination of linear composite mechanics and incremental linear laminate theory. The procedure accounts for initial nonlinear strains, unloading, and in-situ matrix orthotropic nonlinear behavior. The results obtained in applying the procedure to boron/aluminum angleplied laminates show that this is a convenient means to accurately predict the initial tangent properties of angleplied laminates in which the matrix has been strained nonlinearly by the lamination residual stresses. The procedure predicted initial tangent properties results which were in good agreement with measured data obtained from boron/aluminum angleplied laminates.

  19. Diatoms in space: testing prospects for reliable diatom nanotechnology in microgravity

    NASA Astrophysics Data System (ADS)

    Gordon, Richard; Hoover, Richard B.; Tuszynski, Jack A.; de Luis, Javier; Camp, Philip J.; Tiffany, Mary Ann; Nagy, Stephen S.; Fayek, Mostafa; Lopez, Pascal J.; Lerner, Beatriz E.

    2007-09-01

    The worldwide effort to grow nanotechnology, rather than use lithography, focuses on diatoms, single cell eukaryotic algae with ornate silica shells, which can be replaced by oxides and ceramics, or reduced to elemental silicon, to create complex nanostructures with compositions of industrial and electronics importance. Diatoms produce an enormous variety of structures, some of which are microtubule dependent and perhaps sensitive to microgravity. The NASA Single Loop for Cell Culture (SLCC) for culturing and observing microorganisms permits inexpensive, low labor in-space experiments. We propose to send up to the International Space Station diatom cultures of the three diatom species whose genomes are currently being sequenced, plus the giant diatoms of Antarctica (up to 6 mm length for a single cell) and the unique colonial diatom, Bacillaria paradoxa. Bacillaria cells move against each other in partial synchrony, like a sliding deck of cards, by a microfluidics mechanism. Will normal diatoms have aberrant patterns, shapes or motility compared to ground controls? The generation time is typically one day, so that many generations may be examined from one flight. Rapid, directed evolution may be possible running the SLCC as a compustat. The shell shapes and patterns are preserved in hard silica, so that the progress of normal and aberrant morphogenesis may be followed by drying samples on a moving filter paper "diatom tape recorder". With a biodiversity of 100,000 distinct species, diatom nanotechnology may offer a compact and portable nanotechnology toolkit for space exploration anywhere.

  20. Preservation potential of seasonal laminated deposits as a useful tool for environmental analysis in mesotrophic Lake Kizaki, central Japan

    NASA Astrophysics Data System (ADS)

    Ito, Takuma

    2013-09-01

    In this paper discusses the aquatic environment at Lake Kizaki, central Japan, during the last ca. 60 years and describes the importance of laminated sediments in environmental analyses. The flux of total algal carbon increased between 1965 and 1996 while the BSi flux, which can be used in diatom production, showed a larger increase between 1960 and 1998 than typically occurs on average. The flux of dinosterol, an indicator of dinoflagellate production, also increased from 1966 to 1998, and the sedimentary dinoflagellate record correlated with observations of freshwater red tides caused by dinoflagellate blooms. Parallel laminated sediment was determined to have appeared between 1960 and 1995, corresponding to a period of high total algal carbon levels and BSi fluxes. For lamina formation and its preservation process, the thickness of the oxygen-poor layer depended on excessive total algal production during stagnant periods and appeared to be important because nutrients were diffused and accumulated in the oxygen-poor layer from bottom sediments. This could result in diatom blooms at the next overturn period. The development of the thick oxygen-poor layer appeared to be triggered primarily by the presence of excessive nutrients generated by human activities. In general, the occurrence of laminated sediments can provide a useful tool for understanding the eutrophic state in Lake Kizaki.

  1. Specific contribution of lamin A and lamin C in the development of laminopathies

    SciTech Connect

    Sylvius, Nicolas [Laboratory of Genetics of Cardiac Diseases, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, K1Y 4W7 (Canada)], E-mail: sylvius@cng.fr; Hathaway, Andrea; Boudreau, Emilie; Gupta, Pallavi; Labib, Sarah; Bolongo, Pierrette M. [Laboratory of Genetics of Cardiac Diseases, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, K1Y 4W7 (Canada); Rippstein, Peter; McBride, Heidi [University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, K1Y 4W7 (Canada); Bilinska, Zofia T. [First Department of Cardiac Disease, Institute of Cardiology, Alpejska 42, 04-628 Warsaw (Poland); Tesson, Frederique [Laboratory of Genetics of Cardiac Diseases, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, K1Y 4W7 (Canada)

    2008-08-01

    Mutations in the lamin A/C gene are involved in multiple human disorders for which the pathophysiological mechanisms are partially understood. Conflicting results prevail regarding the organization of lamin A and C mutants within the nuclear envelope (NE) and on the interactions of each lamin to its counterpart. We over-expressed various lamin A and C mutants both independently and together in COS7 cells. When expressed alone, lamin A with cardiac/muscular disorder mutations forms abnormal aggregates inside the NE and not inside the nucleoplasm. Conversely, the equivalent lamin C organizes as intranucleoplasmic aggregates that never connect to the NE as opposed to wild type lamin C. Interestingly, the lamin C molecules present within these aggregates exhibit an abnormal increased mobility. When co-expressed, the complex formed by lamin A/C aggregates in the NE. Lamin A and C mutants for lipodystrophy behave similarly to the wild type. These findings reveal that lamins A and C may be differentially affected depending on the mutation. This results in multiple possible physiological consequences which likely contribute in the phenotypic variability of laminopathies. The inability of lamin C mutants to join the nuclear rim in the absence of lamin A is a potential pathophysiological mechanism for laminopathies.

  2. Oceanographic and Biogeochemical Insights from Diatom Genomes

    NASA Astrophysics Data System (ADS)

    Bowler, Chris; Vardi, Assaf; Allen, Andrew E.

    2010-01-01

    Diatoms are the most successful group of eukaryotic phytoplankton in the modern ocean and have risen to dominance relatively quickly over the last 100 million years. Recently completed whole genome sequences from two species of diatom, Thalassiosira pseudonana and Phaeodactylum tricornutum, have revealed a wealth of information about the evolutionary origins and metabolic adaptations that have led to their ecological success. A major finding is that they have incorporated genes both from their endosymbiotic ancestors and by horizontal gene transfer from marine bacteria. This unique melting pot of genes encodes novel capacities for metabolic management, for example, allowing the integration of a urea cycle into a photosynthetic cell. In this review we show how genome-enabled approaches are being leveraged to explore major phenomena of oceanographic and biogeochemical relevance, such as nutrient assimilation and life histories in diatoms. We also discuss how diatoms may be affected by climate change-induced alterations in ocean processes.

  3. DIATOMS: POWERFUL INDICATORS OF ENVIRONMENTAL CHANGE

    EPA Science Inventory

    Diatoms are being used increasingly to assess short- and long-term environmental change, because they are informative, versatile, flexible, and powerful ecological indicators. iatoms respond rapidly to changes in many ecological characteristics. ssemblages are usually diverse and...

  4. Amino Acid biosynthesis pathways in diatoms.

    PubMed

    Bromke, Mariusz A

    2013-01-01

    Amino acids are not only building blocks for proteins but serve as precursors for the synthesis of many metabolites with multiple functions in growth and other biological processes of a living organism. The biosynthesis of amino acids is tightly connected with central carbon, nitrogen and sulfur metabolism. Recent publication of genome sequences for two diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum created an opportunity for extensive studies on the structure of these metabolic pathways. Based on sequence homology found in the analyzed diatomal genes, the biosynthesis of amino acids in diatoms seems to be similar to higher plants. However, one of the most striking differences between the pathways in plants and in diatomas is that the latter possess and utilize the urea cycle. It serves as an important anaplerotic pathway for carbon fixation into amino acids and other N-containing compounds, which are essential for diatom growth and contribute to their high productivity. PMID:24957993

  5. Amino Acid Biosynthesis Pathways in Diatoms

    PubMed Central

    Bromke, Mariusz A.

    2013-01-01

    Amino acids are not only building blocks for proteins but serve as precursors for the synthesis of many metabolites with multiple functions in growth and other biological processes of a living organism. The biosynthesis of amino acids is tightly connected with central carbon, nitrogen and sulfur metabolism. Recent publication of genome sequences for two diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum created an opportunity for extensive studies on the structure of these metabolic pathways. Based on sequence homology found in the analyzed diatomal genes, the biosynthesis of amino acids in diatoms seems to be similar to higher plants. However, one of the most striking differences between the pathways in plants and in diatomas is that the latter possess and utilize the urea cycle. It serves as an important anaplerotic pathway for carbon fixation into amino acids and other N-containing compounds, which are essential for diatom growth and contribute to their high productivity. PMID:24957993

  6. Diatoms in river water-monitoring studies

    Microsoft Academic Search

    F. E. Round

    1991-01-01

    Diatoms grow abundantly in rivers, colonising almost all suitable habitats. They have been used extensively in studies related\\u000a to the monitoring of water quality. This review attempts to draw together data from a wide variety of approaches. The advantage\\u000a of sampling discrete habitats is stressed and particular attention is paid to the diatom flora of stone surfaces (epilithon)\\u000a which is

  7. Flat laminated microbial mat communities

    Microsoft Academic Search

    Jonathan Franks; John F. Stolz

    2009-01-01

    Flat laminated microbial mats are complex microbial ecosystems that inhabit a wide range of environments (e.g., caves, iron springs, thermal springs and pools, salt marshes, hypersaline ponds and lagoons, methane and petroleum seeps, sea mounts, deep sea vents, arctic dry valleys). Their community structure is defined by physical (e.g., light quantity and quality, temperature, density and pressure) and chemical (e.g.,

  8. Thermal stresses in laminated beams

    E-print Network

    Marcano, Victor Manuel

    1983-01-01

    of materials. Boley (1) furnished the most complete treatment to date on the subject of the stress field and temperature effects. However, his analysis of laminated structures is limited to the derivation of the thermoelastic equations for bi... an analysis of the effect of shear deformation in a composite which was heated to a prescribed temperature. The fundamen- tal solution for the thermal stresses were obtained by introducing a shear correction parameter. His analysis was a This thesis...

  9. Curing Stresses in Composite Laminates

    Microsoft Academic Search

    H. T. Hahn; N. J. Pagano

    1975-01-01

    Analysis of curing stresses in resin matrix composite laminates involves a temperature range over which variation of elastic moduli is appreciable. A method based on total stress-strain-temperature relations is formulated and applied to determine the curing stresses in boron\\/epoxy composite lam inates. This method is shown to be preferable to the incremental method because the former requires the thermal strains

  10. Postbuckling of laminated anisotropic panels

    NASA Technical Reports Server (NTRS)

    Jeffrey, Glenda L.

    1987-01-01

    A two-part study of the buckling and postbuckling of laminated anisotropic plates with bending-extensional coupling is presented. The first part involves the development and application of a modified Rayleigh-Ritz analysis technique. Modifications made to the classical technique can be grouped into three areas. First, known symmetries of anisotropic panels are exploited in the selection of approximation functions. Second, a reduced basis technique based on these same symmetries is applied in the linear range. Finally, geometric boundary conditions are enforced via an exterior penalty function approach, rather than relying on choice of approximation functions to satisfy these boundary conditions. Numerical results are presented for both the linear and nonlinear range, with additional studies made to determine the effect of variation in penalty parameter and number of basis vectors. In the second part, six panels possessing anisotropy and bending-extensional coupling are tested. Detailed comparisons are made between experiment and finite element results in order to gain insight into the postbuckling and failure characteristics of such panels. The panels are constructed using two different lamination sequences, and panels with three different aspect ratios were constructed for each lamination sequence.

  11. Stimulation of ice nucleation by marine diatoms

    NASA Astrophysics Data System (ADS)

    Knopf, D. A.; Alpert, P. A.; Wang, B.; Aller, J. Y.

    2011-02-01

    Atmospheric aerosol particles serve as nuclei for ice-crystal formation. As such, these particles are critical to the generation of cirrus clouds, which form from gas and liquid water. Atmospheric aerosols also initiate ice formation in warmer, mixed-phase clouds, where ice crystals coexist with aqueous droplets. Biogenic aerosol particles of terrestrial origin, including bacteria and pollen, can act as ice nuclei. Whether biogenic particles of marine origin also act as ice nuclei has remained uncertain. We exposed the cosmopolitan planktonic diatom species Thalassiosira pseudonana to water vapour and supercooled aqueous sodium chloride under typical tropospheric conditions conducive to cirrus-cloud formation. Ice nucleation was determined using a controlled vapour cooling-stage microscope system. Under all conditions, diatoms initiated ice formation. The presence of diatoms in water increased the temperature for ice formation up to 13K, and in aqueous sodium chloride, ice formed at temperatures up to 30K higher than when diatoms were not present. In addition, diatoms initiated ice formation from water vapour at relative humidities as low as 65%. The rate of ice nucleation was rapid and independent of surface area. We suggest that marine biogenic particles such as diatoms help explain high values and seasonal variations in ice-nuclei concentrations in subpolar regions.

  12. Broken nuclei lamins, nuclear mechanics and disease

    PubMed Central

    Davidson, Patricia M.; Lammerding, Jan

    2014-01-01

    Mutations in lamins, which are ubiquitous nuclear intermediate filaments, lead to a variety of disorders, including muscular dystrophy and dilated cardiomyopathy. Lamins provide nuclear stability, help connect the nucleus to the cytoskeleton, and can modulate chromatin organization and gene expression. Nonetheless, the diverse functions of lamins remain incompletely understood. Here, we focus on the role of lamins on nuclear mechanics and its implication in human diseases. Recent findings suggest that lamin mutations can decrease nuclear stability, increase nuclear fragility, and disturb mechanotransduction signaling, possibly explaining the muscle-specific defects in many laminopathies. At the same time, altered lamin expression has been reported in many cancers, where the resulting increased nuclear deformability could enhance the ability of cells to transit tight interstitial spaces, promoting metastasis. PMID:24309562

  13. Current distribution in high power laminated busbars

    Microsoft Academic Search

    A. T. Bryant; K. K. Vadlapati; J. P. Starkey; A. P. Goldney; S. Y. Kandilidis; D. A. Hinchley

    2011-01-01

    The new LV8900 900 V variable speed drive range from Converteam utilises 3-level NPC inverter topology, featuring multi-layer laminated busbars. These laminates contribute to the commutating stray inductances, and laminate resistive losses in high current and high switching frequency applications are affected by the skin effect. This paper describes models implemented in FastHenry and Simulink accounting for these effects in

  14. Characterization of the Hydra Lamin and Its Gene: A Molecular Phylogeny of Metazoan Lamins

    Microsoft Academic Search

    Andreas Erber; Dieter Riemer; Helmut Hofemeister; Marc Bovenschulte; Reimer Stick; Georgia Panopoulou; Hans Lehrach; Klaus Weber

    1999-01-01

    . We report sequences for nuclear lamins from the teleost fish Danio and six invertebrates. These include two cnidarians (Hydra and Tealia), one priapulid, two echinoderms, and the cephalochordate Branchiostoma. Combining these results with earlier data on Drosophila, Caenorhabditis elegans, and various vertebrates, the following conclusions on lamin evolution can be drawn. First, all invertebrate lamins resemble\\u000a in size the

  15. Lamins at the crossroads of mechanosignaling

    PubMed Central

    Osmanagic-Myers, Selma; Dechat, Thomas

    2015-01-01

    The intermediate filament proteins, A- and B-type lamins, form the nuclear lamina scaffold adjacent to the inner nuclear membrane. B-type lamins confer elasticity, while A-type lamins lend viscosity and stiffness to nuclei. Lamins also contribute to chromatin regulation and various signaling pathways affecting gene expression. The mechanical roles of lamins and their functions in gene regulation are often viewed as independent activities, but recent findings suggest a highly cross-linked and interdependent regulation of these different functions, particularly in mechanosignaling. In this newly emerging concept, lamins act as a mechanostat that senses forces from outside and responds to tension by reinforcing the cytoskeleton and the extracellular matrix. A-type lamins, emerin, and the linker of the nucleoskeleton and cytoskeleton (LINC) complex directly transmit forces from the extracellular matrix into the nucleus. These mechanical forces lead to changes in the molecular structure, modification, and assembly state of A-type lamins. This in turn activates a tension-induced inside-out signaling through which the nucleus feeds back to the cytoskeleton and the extracellular matrix to balance outside and inside forces. These functions regulate differentiation and may be impaired in lamin-linked diseases, leading to cellular phenotypes, particularly in mechanical load-bearing tissues. PMID:25644599

  16. Geometrically nonlinear analysis of laminated elastic structures

    NASA Technical Reports Server (NTRS)

    Reddy, J. N.

    1984-01-01

    Laminated composite plates and shells that can be used to model automobile bodies, aircraft wings and fuselages, and pressure vessels among many other were analyzed. The finite element method, a numerical technique for engineering analysis of structures, is used to model the geometry and approximate the solution. Various alternative formulations for analyzing laminated plates and shells are developed and their finite element models are tested for accuracy and economy in computation. These include the shear deformation laminate theory and degenerated 3-D elasticity theory for laminates.

  17. An improved lamination technique for solar arrays

    NASA Technical Reports Server (NTRS)

    Garcia, A., III; Olson, C.

    1980-01-01

    Encapsulating solar cells by lamination has been plagued with problems such as bubbles, cell shifting, ripples, and cracked cells. A low-cost laminating procedure has been developed using a double vacuum bagging technique and recently improved formulations of ethylene vinyl acetate, successfully minimizing these problems. The lamination fixturing used is described. The causes and cures of various problems are discussed and solutions to these problems presented. The apparent modulus of the face sheet seen by the module being laminated is believed to be the primary variable which must be optimized. Conditions at the module edge are also considered to be important for producing an acceptable product.

  18. The Glass Menagerie: diatoms for novel applications in nanotechnology.

    PubMed

    Gordon, Richard; Losic, Dusan; Tiffany, Mary Ann; Nagy, Stephen S; Sterrenburg, Frithjof A S

    2009-02-01

    Diatoms are unicellular, eukaryotic, photosynthetic algae that are found in aquatic environments. Diatoms have enormous ecological importance on this planet and display a diversity of patterns and structures at the nano- to millimetre scale. Diatom nanotechnology, a new interdisciplinary area, has spawned collaborations in biology, biochemistry, biotechnology, physics, chemistry, material science and engineering. We survey diatom nanotechnology since 2005, emphasizing recent advances in diatom biomineralization, biophotonics, photoluminescence, microfluidics, compustat domestication, multiscale porosity, silica sequestering of proteins, detection of trace gases, controlled drug delivery and computer design. Diatoms might become the first organisms for which the gap in our knowledge of the relationship between genotype and phenotype is closed. PMID:19167770

  19. Primordial Ooze and Continental Drift

    NSDL National Science Digital Library

    In this lesson, students will learn that continental plates drift and this affects the layers of the earth. Following a directed reading and discussion, they will perform an experiment in which they use chocolate frosting and graham crackers to simulate tectonic plates sliding about on the mantle.

  20. Residual stresses in angleplied laminates and their effects on laminate behavior

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1978-01-01

    Evidence of the presence of lamination residual stresses in angleplied laminates were transply cracks and warpage of unsymmetric laminates which occur prior to application of any mechanical load. Lamination residual strains were measured using the embedded strain gage technique. These strains result from the temperature differences between cure and room temperature and vary linearly within this temperature range. Lamination residual stresses were usually present in angleplied fiber composites laminates; they were also present in unidirectional hybrids and superhybrids. For specific applications, the magnitudes of lamination residual stresses were determined and evaluated relative to the anticipated applied stresses. Particular attention was given to cyclic thermal loadings in applications where the thermal cycling takes place over a wide temperature range.

  1. Impact damage in composite laminates

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.

    1988-01-01

    Damage tolerance requirements have become an important consideration in the design and fabrication of composite structural components for modern aircraft. The ability of a component to contain a flaw of a given size without serious loss of its structural integrity is of prime concern. Composite laminates are particularly susceptible to damage caused by transverse impact loading. The ongoing program described is aimed at developing experimental and analytical methods that can be used to assess damage tolerance capabilities in composite structures subjected to impulsive loading. Some significant results of this work and the methodology used to obtain them are outlined.

  2. Symmetries in laminated composite plates

    NASA Technical Reports Server (NTRS)

    Noor, A. K.

    1976-01-01

    The different types of symmetry exhibited by laminated anisotropic fibrous composite plates are identified and contrasted with the symmetries of isotropic and homogeneous orthotropic plates. The effects of variations in the fiber orientation and the stacking sequence of the layers on the symmetries exhibited by composite plates are discussed. Both the linear and geometrically nonlinear responses of the plates are considered. A simple procedure is presented for exploiting the symmetries in the finite element analysis. Examples are given of square, skew and polygonal plates where use of symmetry concepts can significantly reduce the scope and cost of analysis.

  3. Extremophile Diatoms: Implications to the Drake Equation

    NASA Technical Reports Server (NTRS)

    Sterrenburg, Frithjof A. S.; Hoover, Richard B.

    2011-01-01

    Diatoms are unicellular Eukaryotes that (as a group and phylogenetically) are not strictly regarded as extremophiles , since the vast majority of diatoms are mesophilic photoautotrophs. However, among the terrestrial Eukaryotes, diatoms are by far the single group of organisms with the ability to inhabit the greatest range of hostile environments on Earth. They are the dominant eukaryotes in the polar regions; in fumaroles, hot springs and geysers; and in hypersaline and hyperalkaline lakes and pools. Cryophilic species such as Fragilaria sublinearis and Chaetoceras fragilis are able to carry out respiration at extremely low rates at low temperatures in darkness. The Drake Equation refers to the likelihood of there being intelligent life at the technological level of electromagnetic communication. However, consideration of the range of conditions suitable for the habitability of eukaryotic diatoms and prokaryotic extremophiles, the likelihood that life exists elsewhere in the cosmos becomes many orders of magnitude greater than that predicted by the classical Drake Equation. In this paper we review the characteristics of diatoms as eukaryotic extremophiles and consider the implications to adjustments needed to the Drake Equation to assess the possibility that life exists elsewhere in the Universe.

  4. The Genome of the Diatom Thalassiosira Pseudonana: Ecology,

    E-print Network

    The Genome of the Diatom Thalassiosira Pseudonana: Ecology, Evolution, and Metabolism E. Virginia nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand­base pair plastid and 44

  5. Constructing direct porcelain laminate veneer provisionals.

    PubMed

    Kurtz, K S

    1995-05-01

    Historically, teeth prepared for indirect restorations are protected by some type of provisional restoration. This is not always the case for teeth prepared for porcelain laminate veneers because construction of temporaries can be time-consuming. This case report illustrates a quick technique for fabricating a direct composite veneer provisional for teeth prepared for porcelain laminate veneers. PMID:7759691

  6. A damage mechanics tool for laminate delamination

    Microsoft Academic Search

    L. Daudeville; P. Ladeveze

    1993-01-01

    A simplified method based upon damage mechanics for the delamination analysis of carbon-resin composites is presented. In the neighborhood of a laminate structure quasi-straight edge, damage is taken concentrated on the interface between layers. The finite element code EDA, acting as a postprocessor of an elastic laminate shell computation, allows the onset and propagation forecast of delamination. First numerical simulations

  7. Silicone modified resins for graphite fiber laminates

    NASA Technical Reports Server (NTRS)

    Frost, L. W.; Bower, G. M.

    1980-01-01

    Six silicone modified resins were selected for evaluation in unidirectional filament wound graphite laminates. Neat samples of these resins had 1,000 C char residues of 6-63%. The highest flexural values measured for the laminates were a strength of 1,220 MPa and a modulus of 105 GPa. The highest interlaminar shear strength was 72 MPa.

  8. Properties of Low-Expansion Laminates

    NASA Technical Reports Server (NTRS)

    Kural, M.

    1985-01-01

    Laminate elastic constants and coefficients of thermal expansion calculated for near-zero-expansion graphite/aluminum and graphite/ magnesium composites. Report presents results in graphic form for these properties as function of laminate angle and fiber volume fraction for four high-modulus continuous-pitch fiber.

  9. Wettability of graphene-laminated micropillar structures

    NASA Astrophysics Data System (ADS)

    Bong, Jihye; Seo, Keumyoung; Park, Ji-Hoon; Ahn, Joung Real; Ju, Sanghyun

    2014-12-01

    The wetting control of graphene is of great interest for electronic, mechanical, architectural, and bionic applications. In this study, the wettability of graphene-laminated micropillar structures was manipulated by changing the height of graphene-laminated structures and employing the trichlorosilane (HDF-S)-based self-assembly monolayer. Graphene-laminated micropillar structures with HDF-S exhibited higher hydrophobicity (contact angle of 129.5) than pristine graphene thin film (78.8), pristine graphene-laminated micropillar structures (97.5), and HDF-S self-assembled graphene thin film (98.5). Wetting states of the graphene-laminated micropillar structure with HDF-S was also examined by using a urea solution, which flowed across the surface without leaving any residues.

  10. Stationary turbine component with laminated skin

    DOEpatents

    James, Allister W. (Orlando, FL)

    2012-08-14

    A stationary turbine engine component, such as a turbine vane, includes a internal spar and an external skin. The internal spar is made of a plurality of spar laminates, and the external skin is made of a plurality of skin laminates. The plurality of skin laminates interlockingly engage the plurality of spar laminates such that the external skin is located and held in place. This arrangement allows alternative high temperature materials to be used on turbine engine components in areas where their properties are needed without having to make the entire component out of such material. Thus, the manufacturing difficulties associated with making an entire component of such a material and the attendant high costs are avoided. The skin laminates can be made of advanced generation single crystal superalloys, intermetallics and refractory alloys.

  11. The lithologic expression of millennial-scale variability in the Pacific sub-Arctic: IODP Exp. 323, Site U1340

    NASA Astrophysics Data System (ADS)

    Drake, M. K.; Aiello, I. W.; Ravelo, A. C.

    2013-12-01

    Prominent variability in physical properties and lithology are observed in late Pleistocene sediment cores collected during IODP Exp. 323 at Site U1340 on the Bowers Ridge (1292m; Bering Sea). Pronounced lithologic cycles in the last 60 ka of the record are expressed by alternations between more or less laminated diatom ooze and clay-dominated intervals. These cycles correspond to high-frequency variability of stable isotopes that represent D-O type events (Schlung et al. 2012). High-resolution sedimentologic analyses that combine an improved method for the quantitative assessment of the sedimentary components on smear slides with other independent methods (e.g., laser particle size analysis, scanning electron microscopy, physical properties), offer new insights on the lithologic expression of millennial-scale variability in the Pacific sub-Arctic. The sedimentologic data, together with stable isotope geochemistry and physical properties, highlight differences between the laminated (LDO) and the homogenous (HDO) diatom ooze layers that alternate with the clays. The LDOs have lower density and higher porosity, with at least 25% of the diatoms valves preserved versus only 10% is in the HDOs. LDOs diatom valve integrity is correlated to the abundance of diatoms (~30%); no correlation exists for the HDOs. These observations suggest millennial-scale variability has developed under distinct oceanographic conditions for the two types of diatom oozes. This is supported by geochemical data that show LDOs have a lighter ?(_^18)O signature compared to the clay interlayers, while the HDOs do not. Overall, we suggest millennial-scale variability in the Bering Sea is expressed by lithologic cycles that are more complex than in coeval basins recording similar high-frequency cycles (e.g., Santa Barbara Basin). This complexity may reflect a difference in depositional conditions during the formation of the diatom oozes, possibly including the influence of sea-ice during LDO deposition.

  12. Designer diatom episomes delivered by bacterial conjugation.

    PubMed

    Karas, Bogumil J; Diner, Rachel E; Lefebvre, Stephane C; McQuaid, Jeff; Phillips, Alex P R; Noddings, Chari M; Brunson, John K; Valas, Ruben E; Deerinck, Thomas J; Jablanovic, Jelena; Gillard, Jeroen T F; Beeri, Karen; Ellisman, Mark H; Glass, John I; Hutchison Iii, Clyde A; Smith, Hamilton O; Venter, J Craig; Allen, Andrew E; Dupont, Christopher L; Weyman, Philip D

    2015-01-01

    Eukaryotic microalgae hold great promise for the bioproduction of fuels and higher value chemicals. However, compared with model genetic organisms such as Escherichia coli and Saccharomyces cerevisiae, characterization of the complex biology and biochemistry of algae and strain improvement has been hampered by the inefficient genetic tools. To date, many algal species are transformable only via particle bombardment, and the introduced DNA is integrated randomly into the nuclear genome. Here we describe the first nuclear episomal vector for diatoms and a plasmid delivery method via conjugation from Escherichia coli to the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana. We identify a yeast-derived sequence that enables stable episome replication in these diatoms even in the absence of antibiotic selection and show that episomes are maintained as closed circles at copy number equivalent to native chromosomes. This highly efficient genetic system facilitates high-throughput functional characterization of algal genes and accelerates molecular phytoplankton research. PMID:25897682

  13. Diatoms: a fossil fuel of the future.

    PubMed

    Levitan, Orly; Dinamarca, Jorge; Hochman, Gal; Falkowski, Paul G

    2014-03-01

    Long-term global climate change, caused by burning petroleum and other fossil fuels, has motivated an urgent need to develop renewable, carbon-neutral, economically viable alternatives to displace petroleum using existing infrastructure. Algal feedstocks are promising candidate replacements as a 'drop-in' fuel. Here, we focus on a specific algal taxon, diatoms, to become the fossil fuel of the future. We summarize past attempts to obtain suitable diatom strains, propose future directions for their genetic manipulation, and offer biotechnological pathways to improve yield. We calculate that the yields obtained by using diatoms as a production platform are theoretically sufficient to satisfy the total oil consumption of the US, using between 3 and 5% of its land area. PMID:24529448

  14. AN ELEMENTARY MATHEMATICAL PROBLEM ARISING IN DIATOM TAXONOMY

    EPA Science Inventory

    This paper involves a problem confronted by the working diatom taxonomist who must make some basic observations and measurements of the diatom cell wall to achieve an accurate identification. the identification of diatoms to the species level is possible by microscopic observatio...

  15. ORIGINAL PAPER Diatoms and pollen as indicators of water quality

    E-print Network

    Patterson, Timothy

    ORIGINAL PAPER Diatoms and pollen as indicators of water quality and land-use change: a case study reconstruction using pollen and diatoms from the lake sediments showed significant changes in biological community composition through the last *400 years. Altera- tions in the diatom and pollen assemblages were

  16. Sedimentary diatom assemblages and their utility in computing diatom-inferred pH in Sudbury Ontario lakes

    Microsoft Academic Search

    Sushil S. Dixit; Aruna S. Dixit; R. Douglas Evans

    1988-01-01

    Surface sediment diatoms from 30 Sudbury lakes were analyzed to establish a relationship between diatoms and limnological\\u000a characteristics of these lakes. Factor analysis of various chemical and physical variables suggested that most of the variance\\u000a was associated with the pH, pH-metal, and conductivity factors. Factor analysis of common diatom taxa indicated that the distribution\\u000a of most of these diatoms is

  17. A Progressive Damage Model for Laminated Composites Containing Stress Concentrations

    Microsoft Academic Search

    Fu-Kuo Chang; Kuo-Yen Chang

    1987-01-01

    A progressive damage model is presented for notched laminated composites subjected to tensile loading. The model is capable of assessing damage in laminates with arbitrary ply-orientations and of predicting the ultimate tensile strength of the notched laminates. The model consists of two parts, namely, the stress analysis and the failure analysis. Stresses and strains in laminates were analyzed on the

  18. Oxylipin Diversity in the Diatom Family Leptocylindraceae Reveals DHA Derivatives in Marine Diatoms

    PubMed Central

    Nanjappa, Deepak; dIppolito, Giuliana; Gallo, Carmela; Zingone, Adriana; Fontana, Angelo

    2014-01-01

    Marine planktonic organisms, such as diatoms, are prospective sources of novel bioactive metabolites. Oxygenated derivatives of fatty acids, generally referred to as oxylipins, in diatoms comprise a highly diverse and complex family of secondary metabolites. These molecules have recently been implicated in several biological processes including intra- and inter-cellular signaling as well as in defense against biotic stressors and grazers. Here, we analyze the production and diversity of C20 and C22 non-volatile oxylipins in five species of the family Leptocylindraceae, which constitute a basal clade in the diatom phylogeny. We report the presence of species-specific lipoxygenase activity and oxylipin patterns, providing the first demonstration of enzymatic production of docosahexaenoic acid derivatives in marine diatoms. The differences observed in lipoxygenase pathways among the species investigated broadly reflected the relationships observed with phylogenetic markers, thus providing functional support to the taxonomic diversity of the individual species. PMID:24445306

  19. A Live Bioprobe for Studying Diatom-Surface Interactions

    PubMed Central

    Arce, Fernando Tern; Avci, Recep; Beech, Iwona B.; Cooksey, Keith E.; Wigglesworth-Cooksey, Barbara

    2004-01-01

    Atomic force microscopy has been employed to compare the adhesion of Navicula species I diatoms to surfaces of a hydrophobic elastomer, Intersleek, and a hydrophilic mineral, mica. This was accomplished using tipless atomic force microscopy cantilevers functionalized with live diatom cells. Both surfaces were tested with the same diatom bioprobe. Force versus distance curves generated during these experiments revealed comparable cell adhesion strengths on Intersleek and mica, indicating that Navicula diatoms secrete extracellular polymeric substances with hydrophobic and hydrophilic properties. A statistical analysis of force curves was carried out and the average values of works of detachment of a diatom from Intersleek and mica surfaces were determined. PMID:15377513

  20. Severe laminitis in multiple zoo species.

    PubMed

    Wiedner, Ellen; Holland, Jeff; Trupkiewicz, John; Uzal, Francisco

    2014-01-01

    A 10-year record review from a zoological institution in the western USA identified four cases of severe laminitis resulting in rotation and protrusion of the third phalanx through the sole. Laminitis is reported in a Masai giraffe (Giraffa camelopardalis tippelskirchi), a Sichuan takin (Budorcas taxicolor tibetana), a greater Malayan chevrotain (Tragulus napu) and a giant eland (Taurotragus derbianus). This is the first report of severe laminitis with pedal bone rotation and protrusion in multiple species of non-domestic hoofstock, and the first report of this disease in three of these species (takin, chevrotain, and giant eland). PMID:24730432

  1. NOLIN: A nonlinear laminate analysis program

    NASA Technical Reports Server (NTRS)

    Kibler, J. J.

    1975-01-01

    A nonlinear, plane-stress, laminate analysis program, NOLIN, was developed which accounts for laminae nonlinearity under inplane shear and transverse extensional stress. The program determines the nonlinear stress-strain behavior of symmetric laminates subjected to any combination of inplane shear and biaxial extensional loadings. The program has the ability to treat different stress-strain behavior in tension and compression, and predicts laminate failure using any or all of maximum stress, maximum strain, and quadratic interaction failure criteria. A brief description of the program is presented including discussion of the flow of information and details of the input required. Sample problems and a complete listing of the program is also provided.

  2. Indentation law for composite laminates

    NASA Technical Reports Server (NTRS)

    Yang, S. H.

    1981-01-01

    Static indentation tests are described for glass/epoxy and graphite/epoxy composite laminates with steel balls as the indentor. Beam specimens clamped at various spans were used for the tests. Loading, unloading, and reloading data were obtained and fitted into power laws. Results show that: (1) contact behavior is not appreciably affected by the span; (2) loading and reloading curves seem to follow the 1.5 power law; and (3) unloading curves are described quite well by a 2.5 power law. In addition, values were determined for the critical indentation, alpha sub cr which can be used to predict permanent indentations in unloading. Since alpha sub cr only depends on composite material properties, only the loading and an unloading curve are needed to establish the complete loading-unloading-reloading behavior.

  3. Damage of hybrid composite laminates

    NASA Astrophysics Data System (ADS)

    Haery, Haleh A.; Kim, Ho Sung

    2013-08-01

    Hybrid laminates consisting of woven glass fabric/epoxy composite plies and woven carbon fabric/epoxy composite plies are studied for fatigue damage and residual strength. A theoretical framework based on the systems approach is proposed as a guide to deal with the complexity involving uncertainties and a large number of variables in the hybrid composite system. A relative damage sensitivity factor expression was developed for quantitative comparisons between non-hybrid and hybrid composites. Hypotheses derived from the theoretical framework were tested and verified. The first hypothesis was that the difference between two different sets of properties produces shear stress in interface between carbon fibre reinforced plastics (CRP) and glass fibre reinforced plastics (GRP), and eventually become a source for CRP/GRP interfacial delamination or longitudinal cracking. The second hypothesis was that inter-fibre bundle delamination occurs more severely to CRP sub-system than GRP sub-system.

  4. Flat laminated microbial mat communities

    NASA Astrophysics Data System (ADS)

    Franks, Jonathan; Stolz, John F.

    2009-10-01

    Flat laminated microbial mats are complex microbial ecosystems that inhabit a wide range of environments (e.g., caves, iron springs, thermal springs and pools, salt marshes, hypersaline ponds and lagoons, methane and petroleum seeps, sea mounts, deep sea vents, arctic dry valleys). Their community structure is defined by physical (e.g., light quantity and quality, temperature, density and pressure) and chemical (e.g., oxygen, oxidation/reduction potential, salinity, pH, available electron acceptors and donors, chemical species) parameters as well as species interactions. The main primary producers may be photoautotrophs (e.g., cyanobacteria, purple phototrophs, green phototrophs) or chemolithoautophs (e.g., colorless sulfur oxidizing bacteria). Anaerobic phototrophy may predominate in organic rich environments that support high rates of respiration. These communities are dynamic systems exhibiting both spatial and temporal heterogeneity. They are characterized by steep gradients with microenvironments on the submillimeter scale. Diel oscillations in the physical-chemical profile (e.g., oxygen, hydrogen sulfide, pH) and species distribution are typical for phototroph-dominated communities. Flat laminated microbial mats are often sites of robust biogeochemical cycling. In addition to well-established modes of metabolism for phototrophy (oxygenic and non-oxygenic), respiration (both aerobic and anaerobic), and fermentation, novel energetic pathways have been discovered (e.g., nitrate reduction couple to the oxidation of ammonia, sulfur, or arsenite). The application of culture-independent techniques (e.g., 16S rRNA clonal libraries, metagenomics), continue to expand our understanding of species composition and metabolic functions of these complex ecosystems.

  5. Floating assembly of diatom Coscinodiscus sp. microshells.

    PubMed

    Wang, Yu; Pan, Junfeng; Cai, Jun; Zhang, Deyuan

    2012-03-30

    Diatoms have silica frustules with transparent and delicate micro/nano scale structures, two dimensional pore arrays, and large surface areas. Although, the diatom cells of Coscinodiscus sp. live underwater, we found that their valves can float on water and assemble together. Experiments show that the convex shape and the 40 nm sieve pores of the valves allow them to float on water, and that the buoyancy and the micro-range attractive forces cause the valves to assemble together at the highest point of water. As measured by AFM calibrated glass needles fixed in manipulator, the buoyancy force on a single floating valve may reach up to 10 ?N in water. Turning the valves over, enlarging the sieve pores, reducing the surface tension of water, or vacuum pumping may cause the floating valves to sink. After the water has evaporated, the floating valves remained in their assembled state and formed a monolayer film. The bonded diatom monolayer may be valuable in studies on diatom based optical devices, biosensors, solar cells, and batteries, to better use the optical and adsorption properties of frustules. The floating assembly phenomenon can also be used as a self-assembly method for fabricating monolayer of circular plates. PMID:22387476

  6. Analytical solutions for bending analysis of rectangular laminated plates with arbitrary lamination and boundary conditions

    Microsoft Academic Search

    Ali Mohammad Naserian Nik; Masoud Tahani

    2009-01-01

    The intent of the present study is to employ the extended Kantorovich method for semi-analytical solutions of laminated composite\\u000a plates with arbitrary lamination and boundary conditions subjected to transverse loads. The method based on separation of\\u000a spatial variables of displacement field components. Within the displacement field of a first-order shear deformation theory,\\u000a a laminated plate theory is developed. Using the

  7. Method for fabricating laminated uranium composites

    DOEpatents

    Chapman, L.R.

    1983-08-03

    The present invention is directed to a process for fabricating laminated composites of uranium or uranium alloys and at least one other metal or alloy. The laminated composites are fabricated by forming a casting of the molten uranium with the other metal or alloy which is selectively positioned in the casting and then hot-rolling the casting into a laminated plate in or around which the casting components are metallurgically bonded to one another to form the composite. The process of the present invention provides strong metallurgical bonds between the laminate components primarily since the bond disrupting surface oxides on the uranium or uranium alloy float to the surface of the casting to effectively remove the oxides from the bonding surfaces of the components.

  8. Cofiring of integrated magnetic/dielectric laminates

    NASA Astrophysics Data System (ADS)

    Tung, Y. N.; Peng, T. M.; Jean, J. H.; Lin, S. C.

    2011-10-01

    Stress development during cofiring a bi-layer ferrite/dielectric laminate has been investigated by measuring camber development and shrinkage rate difference. The trend of camber development follows a similar pattern to the linear shrinkage rate difference between ferrite and dielectric ceramics. No cofiring defects are observed in the multilayer structure of ferrite and dielectric laminates, indicating that good sintering compatibility between BZN and NiCuZn ferrite exists during cofiring.

  9. Laminopathy-inducing lamin A mutants can induce redistribution of lamin binding proteins into nuclear aggregates

    SciTech Connect

    Huebner, S. [Department of Biochemistry and Molecular Biology, Nuclear Signalling Laboratory, PO Box 13D, Monash University, Clayton, Victoria 3800 (Australia)]. E-mail: stefan.huebner@med.monash.edu.au; Eam, J.E. [Department of Biochemistry and Molecular Biology, Nuclear Signalling Laboratory, PO Box 13D, Monash University, Clayton, Victoria 3800 (Australia); Huebner, A. [Department of Biochemistry and Molecular Biology, Nuclear Signalling Laboratory, PO Box 13D, Monash University, Clayton, Victoria 3800 (Australia); Jans, D.A. [Department of Biochemistry and Molecular Biology, Nuclear Signalling Laboratory, PO Box 13D, Monash University, Clayton, Victoria 3800 (Australia)

    2006-01-15

    Lamins, members of the family of intermediate filaments, form a supportive nucleoskeletal structure underlying the nuclear envelope and can also form intranuclear structures. Mutations within the A-type lamin gene cause a variety of degenerative diseases which are collectively referred to as laminopathies. At the molecular level, laminopathies have been shown to be linked to a discontinuous localization pattern of A-type lamins, with some laminopathies containing nuclear lamin A aggregates. Since nuclear aggregate formation could lead to the mislocalization of proteins interacting with A-type lamins, we set out to examine the effects of FLAG-lamin A N195K and R386K protein aggregate formation on the subnuclear distribution of the retinoblastoma protein (pRb) and the sterol responsive element binding protein 1a (SREBP1a) after coexpression as GFP-fusion proteins in HeLa cells. We observed strong recruitment of both proteins into nuclear aggregates. Nuclear aggregate recruitment of the NPC component nucleoporin NUP153 was also observed and found to be dependent on the N-terminus. That these effects were specific was implied by the fact that a number of other coexpressed karyophilic GFP-fusion proteins, such as the nucleoporin NUP98 and kanadaptin, did not coaggregate with FLAG-lamin A N195K or R386K. Immunofluorescence analysis further indicated that the precursor form of lamin A, pre-lamin A, could be found in intranuclear aggregates. Our results imply that redistribution into lamin A-/pre-lamin A-containing aggregates of proteins such as pRb and SREBP1a could represent a key aspect underlying the molecular pathogenesis of certain laminopathies.

  10. Lamin proteolysis facilitates nuclear events during apoptosis

    PubMed Central

    1996-01-01

    Expression of the adenovirus E1A oncogene stimulates both cell proliferation and p53-dependent apoptosis in rodent cells. p53 implements apoptosis in all or in part through transcriptional activation of bax, the product of which promotes cell death. The adenovirus E1B 19K product is homologous in sequence and in function to Bcl-2, both of which bind to and inhibit the activity of Bax and thereby suppress apoptosis. The E1B 19K protein also interacts with the nuclear lamins, but the role of this interaction in the regulation of apoptosis is not known. Lamins are, however, substrates for members of the interleukin-1 beta-converting enzyme (ICE) family of cysteine proteases that are activated during apoptosis and function downstream of Bcl-2 in the cell death pathway. lamins are degraded during E1A- induced p53-dependent apoptosis. Lamin A and C are cleaved into 47- and 37-kD fragments, respectively, and the site of proteolysis is mapped to a conserved aspartic acid residue at position 230. The cleavage of lamins during apoptosis is consistent with the activation of an ICE- related cysteine protease down-stream of p53. No lamin protease activity was detected in cells expressing the E1B 19K protein, indicating that 19K functions upstream of protease activation in inhibiting apoptosis. Substitution of the aspartic acid at the cleavage site produced a mutant lamin protein that was resistant to proteolysis both in vitro and in vivo. Expression of uncleavable mutant lamin A or B attenuated apoptosis, delaying cell death and the associated DNA fragmentation by 12 h. Mutant lamin expressing cells failed to show the signs of chromatin condensation and nuclear shrinkage typical of cell death by apoptosis. Instead, the nuclear envelope collapsed and the nuclear lamina remained intact. However, the late stage of apoptosis was morphologically unaltered and formation of apoptotic bodies was evident. Thus, lamin breakdown by proteolytic degradation facilitates the nuclear events of apoptosis perhaps by facilitating nuclear breakdown. PMID:8978814

  11. Laminopathy-inducing lamin A mutants can induce redistribution of lamin binding proteins into nuclear aggregates

    Microsoft Academic Search

    S.. Huebner; J. E. Eam; A. Huebner; D. A. Jans

    2006-01-01

    Lamins, members of the family of intermediate filaments, form a supportive nucleoskeletal structure underlying the nuclear envelope and can also form intranuclear structures. Mutations within the A-type lamin gene cause a variety of degenerative diseases which are collectively referred to as laminopathies. At the molecular level, laminopathies have been shown to be linked to a discontinuous localization pattern of A-type

  12. Can hydrodynamics change phosphorus strategies of diatoms?-Nutrient levels and diatom blooms in lotic and lentic ecosystems.

    PubMed

    Wang, Peili; Shen, Hong; Xie, Ping

    2012-02-01

    Diatom blooms occur in many water bodies worldwide, causing significant ecological and social concerns. In order to understand the mechanisms of diatom blooms formation, the effects of varying phosphorus (P) concentration and hydrodynamics on the growth of diatoms were studied by combining results from field observations and laboratory experiments. The field investigation showed that spring diatom blooms (Cyclotella meneghiniana and Stephanodiscus hantzschii) occurred in Lake Taihu and Hanjiang River with similar environmental factors such as water temperature, pH, and dissolved oxygen in 2008. Concentrations of total phosphorus (TP), total nitrogen, and ammonia nitrogen (NH(4)-N) in Lake Taihu were significantly higher than the concentrations in the Hanjiang River. Laboratory experiments were conducted to evaluate growth and physiological responses of four lotic diatoms (Cyclotella atomus, Fragilaria crotonensis, Nitzschia palea, and S. hantzschii, isolated from the Hanjiang River) and three lentic diatoms (C. meneghiniana, Melosira varians, and Stephanodiscus minutulus, isolated from Lake Taihu, Lake Donghu, and Guanqiao Pond, respectively) to various P concentrations under small-scale turbulent and standing conditions. Our results showed that, with turbulence, lotic diatoms C. atomus, F. crotonensis, N. palea, and S. hantzschii demonstrated a significant increase in affinity for P compared with lentic diatoms C. meneghiniana, M. varians, and S. minutulus. Moreover, lotic diatoms C. atomus, F. crotonensis, and N. palea had higher growth rates and photosynthetic efficiencies with small-scale turbulence than with standing conditions both in P-limited and P-replete conditions. Lotic species S. hantzschii and three lentic diatoms (C. meneghiniana, M. varians, and S. minutulus) grew well under standing conditions. Our results may explain our field observation that the occurrence of diatom blooms in lakes is often associated with higher TP concentrations whereas in rivers, diatom blooms occur at a wide range of TP concentrations under flows. Therefore, different hydrodynamics and nutrient concentrations determined the dominant diatom species, according to their habitat-dependent physiological characteristics. PMID:21811794

  13. Biomineralization in diatoms: the role of silacidins.

    PubMed

    Richthammer, Patrick; Brmel, Mandy; Brunner, Eike; van Pe, Karl-Heinz

    2011-06-14

    Diatoms are eukaryotic, unicellular algae encased within siliceous cell walls (frustules), which are precisely reproduced generation by generation. The production of this nanostructured silica is under genetic control and the isolation of specific gene products (the proteins silaffins, silacidins) guiding the biomineralization processes, and which are necessary to produce the frustules, has already been described. Under silicon starvation, the amount of silacidins present in the cell walls of Thalassiosira pseudonana increases relative to other proteins. Natsilacidins, the native and highly phosphorylated silacidins are enormously effective in silica precipitation whereas silacidin A', the nonphosphorylated form, is not. This indicates an important role for natsilacidins in the survival of diatoms under silicic acid depleted conditions. PMID:21560217

  14. Hylleraas hydride binding energy: diatomic electron affinities.

    PubMed

    Chen, Edward S; Keith, Herman; Lim, Tristan; Pham, Dang; Rosenthal, Reece; Herder, Charles; Pai, Sunil; Flores, R A; Chen, Edward C M

    2015-04-01

    Theoretical adiabatic electron affinities are often considered inaccurate because they are referenced to only a single value. Ground state electron affinities for all the main group elements and homonuclear diatomics were identified recently using the normalized binding energy of the hydrogen atom: [0.75420375(3)/2?=?0.37710187(1) eV]. Here we revisit experimental values and extend the identifications to diatomics in the G2-1 set. We assign new ground state electron affinities: (eV) Cl2, 3.2(2); Br2, 2.87(14); CH, 2.1(2); H2, 0.6 ; NH, 1.1, SiH, 1.90. Anion Morse potentials are calculated for H2 and N2 from positive electron affinities and for hyperfine superoxide states for the first time. PMID:25758340

  15. Molecular Tools for Discovering the Secrets of Diatoms

    NSDL National Science Digital Library

    Anastasia Saade (?cole Normale Supérieure in Paris; Department of Biology)

    2009-10-01

    Diatoms are photosynthetic unicellular eukaryotes found in most aquatic environments. They are major players in global biogeochemical cycles, and generate as much oxygen through photosynthesis as terrestrial rainforests do. Insights into their evolutionary origins have been revealed by the whole-genome sequencing of Thalassiosira pseudonana and Phaeodactylum tricornutum. We now know that diatoms contain unusual assortments of genes derived from different sources, including those acquired by horizontal gene transfer from bacteria. These genes confer novel metabolic and signaling capacities that may underlie the extraordinary ecological success of diatoms on Earth today. The availability of a suite of techniques that can be used to monitor and manipulate diatom genes is enhancing our knowledge of their novel characteristics. We highlight these recent developments and illustrate how they are being used to understand different aspects of diatom biology. We also discuss the use of diatoms in commercial applications, such as for nanotechnology and biofuel production.

  16. Silicon diatom frustules as nanostructured photoelectrodes.

    PubMed

    Chandrasekaran, Soundarrajan; Sweetman, Martin J; Kant, Krishna; Skinner, William; Losic, Dusan; Nann, Thomas; Voelcker, Nicolas H

    2014-09-18

    In the quest for solutions to meeting future energy demands, solar fuels play an important role. A particularly promising example is photocatalysis since even incremental improvements in performance in this process are bound to translate into significant cost benefits. Here, we report that semiconducting and high surface area 3D silicon replicas prepared from abundantly available diatom fossils sustain photocurrents and enable solar energy conversion. PMID:25061637

  17. Benthic diatom response to changing environmental conditions

    NASA Astrophysics Data System (ADS)

    Cibic, Tamara; Comici, Cinzia; Bussani, Andrea; Del Negro, Paola

    2012-12-01

    In the Gulf of Trieste (northern Adriatic Sea, Italy) the benthic diatom community dynamics has been studied for seven years (1999-2005) at two sublittoral stations and related to variations of temperature, salinity, nutrient concentrations, freshwater inflow and mucilage. Bin-averaged temperature versus abundance of the main genera revealed that Nitzschia and Navicula presented a positive stepped trend with increasing temperature. An increase of ca. 860 150 cells per cm3 per C was calculated for Navicula and up to 590 170 cells per cm3 per C for Nitzschia. The genus Pleurosigma revealed a negative trend with increasing temperature, with a calculated decrease of ca. 140 60 cells per cm3 per C. A negative relation between Diploneis and temperature was found only in the shallower site. A peak of the tychopelagic genus Cylindrotheca was observed in correspondence with high salinity, but no significant results between bin-averaged salinity and benthic diatom abundance were found. Significant negative relations were obtained between bin-averaged abundance of Pleurosigma and H4SiO4 and NO3- at the deeper station and between the bin-averaged abundance of Gyrosigma and NH4+ at the coastal station. In this site the abundance of Gyrosigma showed a significant increasing trend over the study period. Navicula and Nitzschia seemed to suffer from the presence of mucilage events occurred in summer 2000 and 2004 whereas Diploneis occupied the ecological niche which remained temporarily uncovered by Navicula and Nitzschia. An exceptional freshwater plume with extremely high terrigenous input in November 2000 completely covered the benthic diatom community, causing a remarkable decrease in its total abundance in late autumn and winter 2000-01. The Gulf of Trieste may be considered a natural megacosm due to its geomorphologic characteristics and therefore the benthic diatom response to changing environmental conditions observed in this site could be extended beyond the geographical limits of this particular ecosystem.

  18. Collecting, Cleaning, Mounting, and Photographing Diatoms

    Microsoft Academic Search

    Stephen S. Nagy

    \\u000a This chapter describes techniques used by diatomists to clean and mount diatoms successfully. The techniques involve the use\\u000a of extremely hazardous chemicals that are a serious threat to ones health and physical safety, including strong mineral acids\\u000a that can cause severe skin burns or blindness after brief contact with the skin or eyes; sodium hydroxide, a strong base which\\u000a can

  19. Photoacclimation in the marine diatom Skeletonema costatum

    Microsoft Academic Search

    Tracy Anning; Hugh L. MacIntyre; Sandra M. Pratt; Pippa J. Sammes; Stuart Gibb; Richard J. Geider

    2000-01-01

    Photoacclimation was examined in the marine diatom Skeletonema costatum, which was subjected to reciprocal shifts between irradiances of 50 (low-light) and 1,200 (high-light) mmol photons m 22 s 21 . Cell chlorophyll a and fucoxanthin contents were higher but diadinoxanthin and diatoxanthin contents lower in cells grown at 50 mmol photons m 22 s 21 than in cells shifted to

  20. Seasonal variations in fouling diatom communities on the Yantai coast

    NASA Astrophysics Data System (ADS)

    Yang, Cuiyun; Wang, Jianhua; Yu, Yang; Liu, Sujing; Xia, Chuanhai

    2015-03-01

    Fouling diatoms are a main component of biofilm, and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater, on the Yantai coast, northern Yellow Sea, China, using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3, 7, 14, and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca, Nitzschia, Navicula, Amphora, Gomphonema, and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions, we found that Cylindrotheca grew very fast, which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.

  1. Seasonal variations in fouling diatom communities on the Yantai coast

    NASA Astrophysics Data System (ADS)

    Yang, Cuiyun; Wang, Jianhua; Yu, Yang; Liu, Sujing; Xia, Chuanhai

    2014-11-01

    Fouling diatoms are a main component of biofilm, and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater, on the Yantai coast, northern Yellow Sea, China, using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3, 7, 14, and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca, Nitzschia, Navicula, Amphora, Gomphonema, and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions, we found that Cylindrotheca grew very fast, which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.

  2. Testing Prospects for Reliable Diatom Nanotechnology in Microgravity

    NASA Technical Reports Server (NTRS)

    Gordon, Richard; Hoover, Richard B.; Tuszynski, Jack A.; deLuis, Javier; Camp, Philip J.; Tiffany, Mary Ann; Nagy, Stephen S.; Lerner, Beatriz E.

    2007-01-01

    The worldwide effort to grow nanotechnology, rather than use lithography, focuses on diatoms, single cell eukaryotic algae with ornate silica shells, which can be replaced by oxides and ceramics, or reduced to elemental silicon, to create complex nanostructures with compositions of industrial and electronics importance. Diatoms produce an enormous variety of structures, some of which are microtubule dependent and perhaps sensitive to microgravity. The NASA Single Loop for Cell Culture (SLCC) for culturing and observing microorganisms permits inexpensive, low labor in-space experiments. We propose to send up to the International Space Station diatom cultures of the three diatom species whose genomes are being sequenced, plus the giant diatoms of Antarctica (up to 2 mm diameter for a single cell) and the unique colonial diatom, Bacillaria paradoxa. Bacillaria cells move against each other in partial synchrony, like a sliding deck of cards, by a microfluidics mechanism. Will normal diatoms have aberrant pattern and shape or motility compared to ground controls? The generation time is typically one day, so that many generations may be examined from one flight. Rapid, directed evolution may be possible running the SLCC as a compustat. The shell shapes and patterns are preserved in hard silica, so that the progress of normal and aberrant morphogenesis may be followed by drying samples on a moving filter paper "diatom tape recorder". With a biodiversity of 100,000 distinct species, diatom nanotechnology may offer a compact and portable nanotechnology toolkit for exploration anywhere.

  3. Lamination residual stresses in fiber composites

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Liber, T.

    1975-01-01

    An experimental investigation was conducted to determine the magnitude of lamination residual stresses in angle-ply composites and to evaluate their effects on composite structural integrity. The materials investigated were boron/epoxy, boron/polyimide, graphite/low modulus epoxy, graphite/high modulus epoxy, graphite/polyimide and s-glass/epoxy. These materials were fully characterized. Static properties of laminates were also determined. Experimental techniques using embedded strain gages were developed and used to measure residual strains during curing. The extent of relaxation of lamination residual stresses was investigated. It was concluded that the degree of such relaxation is low. The behavior of angle-ply laminates subjected to thermal cycling, tensile load cycling, and combined thermal cycling with tensile load was investigated. In most cases these cycling programs did not have any measurable influence on residual strength and stiffness of the laminates. In the tensile load cycling tests, the graphite/polyimide shows the highest endurance with 10 million cycle runouts at loads up to 90 percent of the static strength.

  4. Mechanical Behavior of Fabric-Film Laminates

    NASA Technical Reports Server (NTRS)

    Said, Magdi S.

    1999-01-01

    Inflatable structures are gaining wide support in planetary scientific missions as well as commercial applications. For such applications a new class of materials made of laminating thin homogenous films to lightweight fabrics are being considered us structura1 gas envelops. The emerging composite materials are a result of recent advances in the manufacturing cf 1ightweight, high strength fibers, fabrics and scrims. The lamination of these load-carrying members with the proper gas barrier film results in wide range of materials suitable for various loading and environmental conditions. Polyester - based woven fabrics laminated to thin homogeneus film of polyester (Maylar) is an example of this class. This fabric/ film laminate is being considered for the development a material suitable for building large gas envelopes for use in the NASA Ultra Long Duration Balloon Program (ULDB). Compared to commercial homogeneus films, the material provides relatively high strength to weight ratio as well as better resistance to crack and tear propagation. The purpose of this papers is to introduce the mechanical behavior of this class of multi-layers composite and to highlight some of the concerns observed during the characterization of these laminate composites.

  5. Plated lamination structures for integrated magnetic devices

    SciTech Connect

    Webb, Bucknell C.

    2014-06-17

    Semiconductor integrated magnetic devices such as inductors, transformers, etc., having laminated magnetic-insulator stack structures are provided, wherein the laminated magnetic-insulator stack structures are formed using electroplating techniques. For example, an integrated laminated magnetic device includes a multilayer stack structure having alternating magnetic and insulating layers formed on a substrate, wherein each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by an insulating layer, and a local shorting structure to electrically connect each magnetic layer in the multilayer stack structure to an underlying magnetic layer in the multilayer stack structure to facilitate electroplating of the magnetic layers using an underlying conductive layer (magnetic or seed layer) in the stack as an electrical cathode/anode for each electroplated magnetic layer in the stack structure.

  6. Stochastic damage evolution in textile laminates

    NASA Technical Reports Server (NTRS)

    Dzenis, Yuris A.; Bogdanovich, Alexander E.; Pastore, Christopher M.

    1993-01-01

    A probabilistic model utilizing random material characteristics to predict damage evolution in textile laminates is presented. Model is based on a division of each ply into two sublaminas consisting of cells. The probability of cell failure is calculated using stochastic function theory and maximal strain failure criterion. Three modes of failure, i.e. fiber breakage, matrix failure in transverse direction, as well as matrix or interface shear cracking, are taken into account. Computed failure probabilities are utilized in reducing cell stiffness based on the mesovolume concept. A numerical algorithm is developed predicting the damage evolution and deformation history of textile laminates. Effect of scatter of fiber orientation on cell properties is discussed. Weave influence on damage accumulation is illustrated with the help of an example of a Kevlar/epoxy laminate.

  7. Development of tough, moisture resistant laminating resins

    NASA Technical Reports Server (NTRS)

    Brand, R. A.; Harrison, E. S.

    1982-01-01

    Tough, moisture resistant laminating resins for employment with graphite fibers were developed. The new laminating resins exhibited cost, handleability and processing characteristics equivalent to 394K (250 F) curing epoxies. The laminating resins were based on bisphenol A dicyanate and monofunctional cyanates with hydrophobic substituents. These resins sorb only small quantities of moisture at equilibrium (0.5% or less) with minimal glass transition temperature depression and represent an improvement over epoxies which sorb around 2% moisture at equilibrium. Toughening was accomplished by the precipitation of small diameter particles of butadiene nitrile rubber throughout the resin matrix. The rubber domains act as microcrack termini and energy dissipation sites, allowing increased stress accommodation prior to catastrophic failure. A unique blend of amine terminated butadiene nitrile elastomer (MW 2,000) and a high nitrile content butadiene nitrile rubber yielded the desired resin morphology.

  8. Silicone modified resins for graphite fiber laminates

    NASA Technical Reports Server (NTRS)

    Frost, L. W.; Bower, G. M.

    1979-01-01

    The development of silicon modified resins for graphite fiber laminates which will prevent the dispersal of graphite fibers when the composites are burned is discussed. Eighty-five silicone modified resins were synthesized and evaluated including unsaturated polyesters, thermosetting methacrylates, epoxies, polyimides, and phenolics. Neat resins were judged in terms of Si content, homogeneity, hardness, Char formation, and thermal stability. Char formation was estimated by thermogravimetry to 1,000 C in air and in N2. Thermal stability was evaluated by isothermal weight loss measurements for 200 hrs in air at three temperatures. Four silicone modified epoxies were selected for evaluation in unidirectional filament wound graphite laminates. Neat samples of these resins had 1,000 C char residues of 25 to 50%. The highest flexural values measured for the laminates were a strength of 140 kpsi and a modulus of 10 Mpsi. The highest interlaminar shear strength was 5.3 kpsi.

  9. Nonlinear effects on composite laminate thermal expansion

    NASA Technical Reports Server (NTRS)

    Hashin, Z.; Rosen, B. W.; Pipes, R. B.

    1979-01-01

    Analyses of Graphite/Polyimide laminates shown that the thermomechanical strains cannot be separated into mechanical strain and free thermal expansion strain. Elastic properties and thermal expansion coefficients of unidirectional Graphite/Polyimide specimens were measured as a function of temperature to provide inputs for the analysis. The + or - 45 degrees symmetric Graphite/Polyimide laminates were tested to obtain free thermal expansion coefficients and thermal expansion coefficients under various uniaxial loads. The experimental results demonstrated the effects predicted by the analysis, namely dependence of thermal expansion coefficients on load, and anisotropy of thermal expansion under load. The significance of time dependence on thermal expansion was demonstrated by comparison of measured laminate free expansion coefficients with and without 15 day delay at intermediate temperature.

  10. Prediction of Composite Laminate Fracture: Micromechanics and Progressive Fracture

    NASA Technical Reports Server (NTRS)

    Gotsis, P. K.; Chamis, C. C.; Minnetyan, L.

    1998-01-01

    An investigation is described on the prediction of first-ply failure and fracture in selected composite laminates. The laminates are made from glass fibers and graphite fibers in epoxy matrices. Failure envelopes are generated for combined loading of these laminates on the basis of first-ply failure and laminate fracture. The evaluation is performed by a micromechanics-based theory and progressive fracture.

  11. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    SciTech Connect

    Allan, Shawn M.; Baranova, Inessa; Poley, Joseph; Reis, Henrique

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North America. The second task dealt with a study of current lamination processes in the various laminate industries, and development of concepts for integrating RF lamination into new or existing processes. The third task explored the use of a non-destructive technique for analyzing laminate adhesion with the University of Illinois at Urbana-Champaign. The fourth task focused on developing concepts for curved glass lamination using RF lamination. The fifth and sixth tasks together comprised an analysis of laminate product markets, ranking for applicability and commercialization potential, and the development of commercialization strategies for those products. In addition, throughout the project as new experimental data and conventional process data were obtained, the benefits analysis of RF lamination was refined. The goals of the project described above were achieved, positioning RF lamination for the next stage growth envisioned in the original Industrial Grand Challenge proposal. Working with Pilkington North America, lamination of flat autoglass with PVB was achieved, meeting all 16 stringent industry tests. In particular, PVB laminates made with RF lamination passed environmental tests including the high temperature, 120 ???°C bake test, without significant formation of bubbles (defects). The adhesion of PVB to glass was measured using the pummel method. Adhesion values ranging from 1 to 7 out of 10 were obtained. The significant process parameters affecting the environmental and adhesion performance were identified through a designed experiment. Pre-lamination process variables including PVB storage humidity and the de-airing process (vacuum or nip rolling) were significant, as well as the level of pressure applied to the laminate during the RF process. Analysis of manufacturing with RF lamination equipment, based on the processes developed indicated that 3 RF presses could replace a typical auto-industry autoclave to achieve equal or greater throughput with possibly less capital cost and smaller footprint. Concepts for curved lamination id

  12. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    SciTech Connect

    Allan, Shawn M.

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North America. The second task dealt with a study of current lamination processes in the various laminate industries, and development of concepts for integrating RF lamination into new or existing processes. The third task explored the use of a non-destructive technique for analyzing laminate adhesion with the University of Illinois at Urbana-Champaign. The fourth task focused on developing concepts for curved glass lamination using RF lamination. The fifth and sixth tasks together comprised an analysis of laminate product markets, ranking for applicability and commercialization potential, and the development of commercialization strategies for those products. In addition, throughout the project as new experimental data and conventional process data were obtained, the benefits analysis of RF lamination was refined. The goals of the project described above were achieved, positioning RF lamination for the next stage growth envisioned in the original Industrial Grand Challenge proposal. Working with Pilkington North America, lamination of flat autoglass with PVB was achieved, meeting all 16 stringent industry tests. In particular, PVB laminates made with RF lamination passed environmental tests including the high temperature, 120 C bake test, without significant formation of bubbles (defects). The adhesion of PVB to glass was measured using the pummel method. Adhesion values ranging from 1 to 7 out of 10 were obtained. The significant process parameters affecting the environmental and adhesion performance were identified through a designed experiment. Pre-lamination process variables including PVB storage humidity and the de-airing process (vacuum or nip rolling) were significant, as well as the level of pressure applied to the laminate during the RF process. Analysis of manufacturing with RF lamination equipment, based on the processes developed indicated that 3 RF presses could replace a typical auto-industry autoclave to achieve equal or greater throughput with possibly less capital cost and smaller footprint. Concepts for curved lamination identifying castable molds for

  13. Multi-layer laminate structure and manufacturing method

    SciTech Connect

    Keenihan, James R. (Midland, MI); Cleereman, Robert J. (Midland, MI); Eurich, Gerald (Merrill, MI); Graham, Andrew T. (Midland, MI); Langmaid, Joe A. (Caro, MI)

    2012-04-24

    The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

  14. Multi-layer laminate structure and manufacturing method

    DOEpatents

    Keenihan, James R.; Cleereman, Robert J.; Eurich, Gerald; Graham, Andrew T.; Langmaid, Joe A.

    2013-01-29

    The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

  15. Impact analysis of composite laminates with multiple delaminations

    Microsoft Academic Search

    N. Hu; H. Sekine; H. Fukunaga; Z. H. Yao

    1999-01-01

    This paper concerns with the transient response of composite laminates with multiple delaminations subjected to low-velocity impact by a rigid ball. The finite element method based on the Mindlin plate theory is employed to describe the motion and deformation of the laminates. A Hertzian-type indentation law is adopted to calculate the impact force between the laminates and the rigid ball.

  16. Fatigue reliability analysis of composite laminates under spectrum stress

    Microsoft Academic Search

    T. Y. Kam; S. Y. Tsai; K. H. Chu

    1997-01-01

    Fatigue reliability of graphite\\/epoxy composite laminates under uniaxial spectrum stress is studied using the modified ?-method. A number of cumulative damage models are adopted to construct the limit state equation for the laminates in the reliabilty analysis. Statistics of fatigue life distributions of the laminates under cyclic stresses of constant amplitudes obtained from tests are used for the reliability assessment

  17. The dilemma of disappearing diatoms: Incorporating diatom dissolution data into palaeoenvironmental modelling and reconstruction

    Microsoft Academic Search

    David B. Ryves; Richard W. Battarbee; Sherilyn C. Fritz

    2009-01-01

    Taphonomic issues pose fundamental challenges for Quaternary scientists to recover environmental signals from biological proxies and make accurate inferences of past environments. The problem of microfossil preservation, specifically diatom dissolution, remains an important, but often overlooked, source of error in both qualitative and quantitative reconstructions of key variables from fossil samples, especially those using relative abundance data. A first step

  18. Integration of TiO2 into the diatom Thalassiosira weissflogii during frustule synthesis

    NASA Astrophysics Data System (ADS)

    Lang, Yvonne; Monte, Francisco Del; Rodriguez, Brian J.; Dockery, Peter; Finn, David P.; Pandit, Abhay

    2013-11-01

    Nature has inspired the design of complex hierarchical structures in the field of material science. Diatoms, unicellular algae with a hallmark intricate siliceous cell wall, have provided such a stimulus. Altering the chemistry of the diatom frustule has been explored to expand on the potential application of diatoms. The ability to modify the diatom in vivo opens the possibility to tailor the diatom to the end application. Herein, we report the chemical modification of the living diatom T. weissflogii using a titania precursor, titanium (IV) bis-(ammonium lactato)-dihydroxide (TiBALDH). Incorporation of Ti into the diatom is achieved via repeated treatment of cultures with non-toxic concentrations of TiBALDH. The characteristic architectural features of the diatom are unaltered following chemical modification. Transformation of the living diatom provides opportunity to confer novel structural, chemical or functional properties upon the diatom. We report on a photocatalytic ability imparted upon the TiBALDH-modified diatom.

  19. Diatoms respire nitrate to survive dark and anoxic conditions

    PubMed Central

    Kamp, Anja; de Beer, Dirk; Nitsch, Jana L.; Lavik, Gaute; Stief, Peter

    2011-01-01

    Diatoms survive in dark, anoxic sediment layers for months to decades. Our investigation reveals a correlation between the dark survival potential of marine diatoms and their ability to accumulate NO3? intracellularly. Axenic strains of benthic and pelagic diatoms that stored 11274 mM NO3? in their cells survived for 628 wk. After sudden shifts to dark, anoxic conditions, the benthic diatom Amphora coffeaeformis consumed 8487% of its intracellular NO3? pool within 1 d. A stable-isotope labeling experiment proved that 15NO3? consumption was accompanied by the production and release of 15NH4+, indicating dissimilatory nitrate reduction to ammonium (DNRA). DNRA is an anaerobic respiration process that is known mainly from prokaryotic organisms, and here shown as dissimilatory nitrate reduction pathway used by a eukaryotic phototroph. Similar to large sulfur bacteria and benthic foraminifera, diatoms may respire intracellular NO3? in sediment layers without O2 and NO3?. The rapid depletion of the intracellular NO3? storage, however, implies that diatoms use DNRA to enter a resting stage for long-term survival. Assuming that pelagic diatoms are also capable of DNRA, senescing diatoms that sink through oxygen-deficient water layers may be a significant NH4+ source for anammox, the prevalent nitrogen loss pathway of oceanic oxygen minimum zones. PMID:21402908

  20. Continental diatoms as indicators of long-term environmental change

    USGS Publications Warehouse

    Bradbury, J. Platt

    1999-01-01

    It is curious that diatoms, whose short lifespans and capacity for rapid regeneration make them especially suitable for short-term paleoenvironmental studies, would also have a significant role as indicators of long-term environmental change. This chapter explores the nature of long diatom records, their relation to global environmental changes, guidelines for their interpretation, and problems common to such records.

  1. Estimations of Rotational Relaxation Parameters in Diatomic Gases

    E-print Network

    Riabov, Vladimir V.

    -translational processes in a diatomic gas. The calculations of relaxation time, viscosity, thermal conductivity are analyzed for the cases of nitrogen flow in underexpanded jets and supersonic rarefied gas flow near-translational processes in a diatomic gas [5], [6]. The calculations of relaxation time, viscosity, thermal conductivity

  2. Tracking the sterol biosynthesis pathway of the diatom Phaeodactylum tricornutum.

    PubMed

    Fabris, Michele; Matthijs, Michiel; Carbonelle, Sophie; Moses, Tessa; Pollier, Jacob; Dasseville, Renaat; Baart, Gino J E; Vyverman, Wim; Goossens, Alain

    2014-11-01

    Diatoms are unicellular photosynthetic microalgae that play a major role in global primary production and aquatic biogeochemical cycling. Endosymbiotic events and recurrent gene transfers uniquely shaped the genome of diatoms, which contains features from several domains of life. The biosynthesis pathways of sterols, essential compounds in all eukaryotic cells, and many of the enzymes involved are evolutionarily conserved in eukaryotes. Although well characterized in most eukaryotes, the pathway leading to sterol biosynthesis in diatoms has remained hitherto unidentified. Through the DiatomCyc database we reconstructed the mevalonate and sterol biosynthetic pathways of the model diatom Phaeodactylum tricornutum in silico. We experimentally verified the predicted pathways using enzyme inhibitor, gene silencing and heterologous gene expression approaches. Our analysis revealed a peculiar, chimeric organization of the diatom sterol biosynthesis pathway, which possesses features of both plant and fungal pathways. Strikingly, it lacks a conventional squalene epoxidase and utilizes an extended oxidosqualene cyclase and a multifunctional isopentenyl diphosphate isomerase/squalene synthase enzyme. The reconstruction of the P. tricornutum sterol pathway underscores the metabolic plasticity of diatoms and offers important insights for the engineering of diatoms for sustainable production of biofuels and high-value chemicals. PMID:24996048

  3. RESEARCH ARTICLE Open Access The model marine diatom Thalassiosira

    E-print Network

    Julius, Matthew L.

    RESEARCH ARTICLE Open Access The model marine diatom Thalassiosira pseudonana likely descended from pseudonana Background Diatoms are unicellular photosynthetic algae with second- ary, red-2148/11/125 2011 Alverson et al; licensee BioMed Central Ltd. This is an Open Access article distributed under

  4. Lake warming favours small-sized planktonic diatom species

    PubMed Central

    Winder, Monika; Reuter, John E.; Schladow, S. Geoffrey

    2008-01-01

    Diatoms contribute to a substantial portion of primary production in the oceans and many lakes. Owing to their relatively heavy cell walls and high nutrient requirements, planktonic diatoms are expected to decrease with climate warming because of reduced nutrient redistribution and increasing sinking velocities. Using a historical dataset, this study shows that diatoms were able to maintain their biovolume with increasing stratification in Lake Tahoe over the last decades; however, the diatom community structure changed. Increased stratification and reduced nitrogen to phosphorus ratios selected for small-celled diatoms, particularly within the Cyclotella genus. An empirical model showed that a shift in phytoplankton species composition and cell size was consistent within different depth strata, indicating that altered nutrient concentrations were not responsible for the change. The increase in small-celled species was sufficient to decrease the average diatom size and thus sinking velocity, which strongly influences energy transfer through the food web and carbon cycling. Our results show that within the diverse group of diatoms, small-sized species with a high surface area to volume ratio were able to adapt to a decrease in mixing intensity, supporting the hypotheses that abiotic drivers affect the size structure of planktonic communities and that warmer climate favours small-sized diatom cells. PMID:18812287

  5. Benthic diatoms in lakes: environmental drivers and ecological

    E-print Network

    diatom guilds seems to be decoupled from nutrient availability in acidic compared to high pH aquatic producers, especially diatoms, displayed a stronger response to pH than macro- invertebrates, possibly due, caution is advised in interpreting the response of some species to nutrients, as pH dependencies might

  6. Late Neogene changes in diatom sedimentation in the North Pacific

    USGS Publications Warehouse

    Barron, J.A.

    1998-01-01

    During the late Neogene, North Pacific diatom sedimentation underwent major changes in response to high-latitude cooling and changes in surface and deep water circulation. At 9 Ma diatom mass accumulation rates (MARs) increased in the NW Pacific and off northeast Japan, possibly due to shoaling of the Isthmus of Panama, which lead to an enrichment of nutrients in North Pacific deep waters. During the latest Miocene, diatom MARs increased progressively off southern California (6.5 Ma), at high latitudes of the North Pacific (6.2 Ma), and off northeastern Japan (5.5 Ma), presumably in response to high latitude cooling. At about 4.5 Ma diatom sedimentation abruptly increased in the NW Pacific but declined off Japan and California, coincident with the onset of a prolonged period of high-latitude warmth. Enhanced upwelling of nutrient-rich deep waters in the NW Pacific probably stimulated diatom production there. A major step in high latitude cooling at 2.7 Ma caused a reversal of these mid Pliocene diatom sedimentation patterns. Upwelling of deep, nutrient-rich waters waned at higher latitudes, leading to a decline in diatom productivity; while wind-driven, coastal upwelling increased off southern California and stimulated diatom growth.

  7. ORIGINAL ARTICLE Diatom assemblages promote ice formation in large

    E-print Network

    Lee Jr., Richard E.

    sampled from the ice-covered Laurentian Great Lakes. We hypothesize that ice formation promotes attachmentORIGINAL ARTICLE Diatom assemblages promote ice formation in large lakes NA D'souza1,3 , Y a means for the diatoms to be recruited to the overlying lake ice, thereby increasing their fitness

  8. The Central Carbon and Energy Metabolism of Marine Diatoms

    PubMed Central

    Obata, Toshihiro; Fernie, Alisdair R.; Nunes-Nesi, Adriano

    2013-01-01

    Diatoms are heterokont algae derived from a secondary symbiotic event in which a eukaryotic host cell acquired an eukaryotic red alga as plastid. The multiple endosymbiosis and horizontal gene transfer processes provide diatoms unusual opportunities for gene mixing to establish distinctive biosynthetic pathways and metabolic control structures. Diatoms are also known to have significant impact on global ecosystems as one of the most dominant phytoplankton species in the contemporary ocean. As such their metabolism and growth regulating factors have been of particular interest for many years. The publication of the genomic sequences of two independent species of diatoms and the advent of an enhanced experimental toolbox for molecular biological investigations have afforded far greater opportunities than were previously apparent for these species and re-invigorated studies regarding the central carbon metabolism of diatoms. In this review we discuss distinctive features of the central carbon metabolism of diatoms and its response to forthcoming environmental changes and recent advances facilitating the possibility of industrial use of diatoms for oil production. Although the operation and importance of several key pathways of diatom metabolism have already been demonstrated and determined, we will also highlight other potentially important pathways wherein this has yet to be achieved. PMID:24957995

  9. Fatigue of Wind Blade Laminates:Fatigue of Wind Blade Laminates: Effects of Resin and Fabric Structure

    E-print Network

    Fatigue of Wind Blade Laminates:Fatigue of Wind Blade Laminates: Effects of Resin and Fabric Materials Recent Findings, Resin and Fabric Structure Interactions for InfusedStructure Interactions and potential fibers, fabrics, resins, fiber sizings, processes, processing aids, laminate lay-ups, fiber

  10. Reciprocal knock-in mice to investigate the functional redundancy of lamin B1 and lamin B2

    PubMed Central

    Lee, John M.; Tu, Yiping; Tatar, Angelica; Wu, Daniel; Nobumori, Chika; Jung, Hea-Jin; Yoshinaga, Yuko; Coffinier, Catherine; de Jong, Pieter J.; Fong, Loren G.; Young, Stephen G.

    2014-01-01

    Lamins B1 and B2 (B-type lamins) have very similar sequences and are expressed ubiquitously. In addition, both Lmnb1- and Lmnb2-deficient mice die soon after birth with neuronal layering abnormalities in the cerebral cortex, a consequence of defective neuronal migration. The similarities in amino acid sequences, expression patterns, and knockout phenotypes raise the question of whether the two proteins have redundant functions. To investigate this topic, we generated reciprocal knock-in micemice that make lamin B2 from the Lmnb1 locus (Lmnb1B2/B2) and mice that make lamin B1 from the Lmnb2 locus (Lmnb2B1/B1). Lmnb1B2/B2 mice produced increased amounts of lamin B2 but no lamin B1; they died soon after birth with neuronal layering abnormalities in the cerebral cortex. However, the defects in Lmnb1B2/B2 mice were less severe than those in Lmnb1-knockout mice, indicating that increased amounts of lamin B2 partially ameliorate the abnormalities associated with lamin B1 deficiency. Similarly, increased amounts of lamin B1 in Lmnb2B1/B1 mice did not prevent the neurodevelopmental defects elicited by lamin B2 deficiency. We conclude that lamins B1 and B2 have unique roles in the developing brain and that increased production of one B-type lamin does not fully complement loss of the other. PMID:24672053

  11. Nitrate Utilization by the Diatom Skeletonema costatum

    PubMed Central

    Serra, Juan L.; Llama, Maria J.; Cadenas, Eduardo

    1978-01-01

    Nitrate utilization has been characterized in nitrogen-deficient cells of the marine diatom Skeletonema costatum. In order to separate nitrate uptake from nitrate reduction, nitrate reductase activity was suppressed with tungstate. Neither nitrite nor the presence of amino acids in the external medium or darkness affects nitrate uptake kinetics. Ammonium strongly inhibits carrier-mediated nitrate uptake, without affecting diffusion transfer. A model is proposed for the uptake and assimilation of nitrate in S. costatum and their regulation by ammonium ions. PMID:16660653

  12. Regulated growth of diatom cells on self-assembled monolayers

    PubMed Central

    Umemura, Kazuo; Yamada, Tomoaki; Maeda, Yuta; Kobayashi, Koichi; Kuroda, Reiko; Mayama, Shigeki

    2007-01-01

    We succeeded in regulating the growth of diatom cells on chemically modified glass surfaces. Glass surfaces were functionalized with -CF3, -CH3, -COOH, and -NH2 groups using the technique of self-assembled monolayers (SAM), and diatom cells were subsequently cultured on these surfaces. When the samples were rinsed after the adhesion of the diatom cells on the modified surfaces, the diatoms formed two dimensional arrays; this was not possible without the rinsing treatment. Furthermore, we examined the number of cells that grew and their motility by time-lapse imaging in order to clarify the interaction between the cells and SAMs. We hope that our results will be a basis for developing biodevices using living photosynthetic diatom cells. PMID:17381834

  13. Biotemplated diatom silica-titania materials for air purification.

    PubMed

    Van Eynde, Erik; Tytgat, Tom; Smits, Marianne; Verbruggen, Sammy W; Hauchecorne, Birger; Lenaerts, Silvia

    2013-04-01

    We present a novel manufacture route for silica-titania photocatalysts using the diatom microalga Pinnularia sp. Diatoms self-assemble into porous silica cell walls, called frustules, with periodic micro-, meso- and macroscale features. This unique hierarchical porous structure of the diatom frustule is used as a biotemplate to incorporate titania by a sol-gel methodology. Important material characteristics of the modified diatom frustules under study are morphology, crystallinity, surface area, pore size and optical properties. The produced biosilica-titania material is evaluated towards photocatalytic activity for NOx abatement under UV radiation. This research is the first step to obtain sustainable, well-immobilised silica-titania photocatalysts using diatoms. PMID:23128085

  14. Applications of Diatoms as Potential Microalgae in Nanobiotechnology

    PubMed Central

    Jamali, Ali Akbar; Akbari, Fariba; Ghorakhlu, Mohamad Moradi; de la Guardia, Miguel; Yari Khosroushahi, Ahmad

    2012-01-01

    Introduction Diatoms are single cell eukaryotic microalgae, which present in nearly every water habitat make them ideal tools for a wide range of applications such as oil explora-tion, forensic examination, environmental indication, biosilica pattern generation, toxicity testing and eutrophication of aqueous ecosystems. Methods Essential information on diatoms were reviewed and discussed towards impacts of diatoms on biosynthesis and bioremediation. Results In this review, we present the recent progress in this century on the application of diatoms in waste degradation, synthesis of biomaterial, biomineraliza-tion, toxicity and toxic effects of mineral elements evaluations. Conclusion Diatoms can be considered as metal toxicity bioindicators and they can be applied for biomineralization, synthesis of biomaterials, and degradation of wastes. PMID:23678445

  15. Prediction of Composite Laminate Fracture: Micromechanics and Progressive Fracture

    NASA Technical Reports Server (NTRS)

    Gotsis, P. K.; Chamis, C. C.; Minnetyan, L.

    1996-01-01

    This report describes an investigation to predict first-ply failure and final fracture in selected composite laminates subjected to inplane loads. The laminates were composed of glass fiber and graphite fibers in epoxy matrices. Failure envelopes based on first-ply failure and laminate fracture were generated for combined loading of these laminates. Predictions were evaluated by micromechanics-based theory and progressive fracture. The results show that, for most cases, combined tensile loading significantly enhanced the laminate fracture stress in comparison to the uniaxial loading.

  16. Characterization of graphite/epoxy laminates for aeroelastic tailoring

    NASA Technical Reports Server (NTRS)

    Shyprykevich, P.

    1979-01-01

    A study of interaction between wing bending and twist by graphite/epoxy anisotropic laminates used in aircraft wing skins is presented. The laminates were used as covers for subscale box beams supported as a cantilever and tested in tip shear and tip torque, measuring beam response with a reflected light technique. The results indicated that the in-plane stiffness properties of anisotropic laminates can be predicted if the layer properties of the composite materials are known; thus, the coupled bending/twist response of wing type structures made from these laminates can be determined provided the limits of the laminate linear behavior are not significantly exceeded.

  17. Doped LZO buffer layers for laminated conductors

    DOEpatents

    Paranthaman, Mariappan Parans (Knoxville, TN) [Knoxville, TN; Schoop, Urs (Westborough, MA) [Westborough, MA; Goyal, Amit (Knoxville, TN) [Knoxville, TN; Thieme, Cornelis Leo Hans (Westborough, MA) [Westborough, MA; Verebelyi, Darren T. (Oxford, MA) [Oxford, MA; Rupich, Martin W. (Framingham, MA) [Framingham, MA

    2010-03-23

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  18. Multifunctional microtruss laminates: textile synthesis, and properties

    Microsoft Academic Search

    D. J. Sypeck; H. N. G. Wadley

    2001-01-01

    Open cell periodic metal truss structures can exhibit significantly higher stiffnesses and strengths than stochastic cellular metal structures of the same relative density while still providing high mechanical energy absorption and efficient heat exchange opportunities. Here, a potentially inexpensive textile-based approach to the synthesis of periodic metal microtruss laminates is reported. The process consists of selecting a wire weave, laying

  19. Laminated insulators having heat dissipation means

    DOEpatents

    Niemann, R.C.; Mataya, K.F.; Gonczy, J.D.

    1980-04-24

    A laminated body is provided with heat dissipation capabilities. The insulator body is formed by dielectric layers interleaved with heat conductive layers, and bonded by an adhesive to form a composite structure. The heat conductive layers include provision for connection to an external thermal circuit.

  20. Thermal postbuckling behavior of laminated composite plates

    SciTech Connect

    Singh, G.; Rao, G.V.; Lyengar, N.G.R. (Vikram Sarabhai Space Center, Trivandrum (India))

    1994-06-01

    Thermal buckling and postbuckling behavior of shear deformable laminated composite plates is investigated by employing a four-node rectangular C(sup 1) continuous finite element. The investigation reveals that the postbuckling path may not remain stable throughout. It is shown that secondary instabilities coupled with changes in the spatial deformation do take place from the postbuckling path. 15 refs.

  1. Probabilistic sizing of laminates with uncertainties

    NASA Technical Reports Server (NTRS)

    Shah, A. R.; Liaw, D. G.; Chamis, C. C.

    1993-01-01

    A reliability based design methodology for laminate sizing and configuration for a special case of composite structures is described. The methodology combines probabilistic composite mechanics with probabilistic structural analysis. The uncertainties of constituent materials (fiber and matrix) to predict macroscopic behavior are simulated using probabilistic theory. Uncertainties in the degradation of composite material properties are included in this design methodology. A multi-factor interaction equation is used to evaluate load and environment dependent degradation of the composite material properties at the micromechanics level. The methodology is integrated into a computer code IPACS (Integrated Probabilistic Assessment of Composite Structures). Versatility of this design approach is demonstrated by performing a multi-level probabilistic analysis to size the laminates for design structural reliability of random type structures. The results show that laminate configurations can be selected to improve the structural reliability from three failures in 1000, to no failures in one million. Results also show that the laminates with the highest reliability are the least sensitive to the loading conditions.

  2. HYGROTHERMAL AGING OF POLYIMIDE MATRIX COMPOSITE LAMINATES

    E-print Network

    Nairn, John A.

    HYGROTHERMAL AGING OF POLYIMIDE MATRIX COMPOSITE LAMINATES John A. Nairn and Man-Hee Han Materials-0560, USA SUMMARY: Two polyimide-matrix systems were subjected to a series of hygrothermal aging experiments at various temperatures and relative humidities. For each aging condition, we measured the microcracking

  3. Micro-Cracking Detection in Laminated Composites

    NASA Technical Reports Server (NTRS)

    Chu, Tsuchin; Leyte, Alma; DiGregorio, Anthony; Russell, Samuel S.; Walker, James L.; Thom, Robert (Technical Monitor)

    2002-01-01

    Porosity and fatigue cracking are two critical factors that affect the performance and safety of cryogenic fuel tanks and feedlines made from unlined laminated or weaved carbon/epoxy materials. This paper presents the experiments to induce fatigue cracking of laminated composites through thermal cycling as well as the feasibility of using Thermography and Ultrasound Spectroscopy technology (UT) to detect and measure such micro-cracking. Carbon/epoxy laminated composite panels were built and cut into strips. These specimens were partially submerged in liquid nitrogen while subjected to various loads on a test machine. Edges of some specimens were polished and etched to determine the degree of micro-cracking. The rest of specimens were then examined with Thermography and Ultrasound Spectroscopy NDE systems to investigate the feasibility of finding such micro-cracking in the laminated composites. Thermography is utilized to determine changes in thermal diffusivity. The degree of cracking may reduce the apparent thermal diffusivity and therefore change the thermal response on the surface. Thermography testing was conducted on a group of specimens where it is desired to have some correlation between the predetermined stress and the thermography data. Ultrasound Spectroscopy was used to determine peak changes between the pre-stressed and stressed samples. Data from the inspections were analyzed and the results are presented in this paper.

  4. Determining Shear Stress Distribution in a Laminate

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.

    2010-01-01

    A "simplified shear solution" method approximates the through-thickness shear stress distribution within a composite laminate based on an extension of 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 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. The method has been incorporated within the HyperSizer commercial structural sizing software to improve its predictive capability for designing composite structures. The HyperSizer structural sizing software is used extensively by NASA to design composite structures. In the case of through-thickness shear loading on panels, HyperSizer previously included a basic, industry-standard, method for approximating the resulting shear stress distribution in sandwich panels. However, no such method was employed for solid laminate panels. The purpose of the innovation is to provide an approximation of the through-thickness shear stresses in a solid laminate given the through-thickness shear loads (Qx and Qy) on the panel. The method was needed for implementation within the HyperSizer structural sizing software so that the approximated ply-level shear stresses could be utilized in a failure theory to assess the adequacy of a panel design. The simplified shear solution method was developed based on extending and generalizing bi-material beam theory to plate-like structures. It is assumed that the through-thickness shear stresses arise due to local bending of the laminate induced by the through-thickness shear load, and by imposing equilibrium both vertically and horizontally, the through-thickness shear stress distribution can be calculated. The resulting shear stresses integrate to the applied shear load, are continuous at the ply interfaces, and are zero at the laminate-free surfaces. If both Qx and Qy shear loads are present, it is assumed that they act independently and that their effects can be superposed. The calculated shear stresses can be rotated within each ply to the principal material coordinates for use in a ply-level failure criterion. The novelty of the simplified shear solution method is its simplicity and the fact that it does not require solution of a particular boundary value problem. The advantages of the innovation are that an approximation of the though-thickness shear stress distribution can be quickly determined for any solid laminate or solid laminate region within a stiffened panel.

  5. Diatoms from surface sediments of the northern part of Lake Tanganyika

    Microsoft Academic Search

    A. G. Caljon; C. Z. Cocquyt

    1992-01-01

    227 Diatom taxa were observed in the surface sediments of the northern part of Lake Tanganyika, including 1 new to science: Amphora tanganyikae. The diatom community of these sediments is mainly composed of benthic organisms while planktonic diatoms are rather rare. Many brackish-water and a few marine organisms were observed. Cosmopolitan organisms (77.1%) dominate the diatom flora but tropical, tropical

  6. Diatom assemblages promote ice formation in large lakes

    PubMed Central

    D'souza, N A; Kawarasaki, Y; Gantz, J D; Lee, R E; Beall, B F N; Shtarkman, Y M; Koer, Z A; Rogers, S O; Wildschutte, H; Bullerjahn, G S; McKay, R M L

    2013-01-01

    We present evidence for the directed formation of ice by planktonic communities dominated by filamentous diatoms sampled from the ice-covered Laurentian Great Lakes. We hypothesize that ice formation promotes attachment of these non-motile phytoplankton to overlying ice, thereby maintaining a favorable position for the diatoms in the photic zone. However, it is unclear whether the diatoms themselves are responsible for ice nucleation. Scanning electron microscopy revealed associations of bacterial epiphytes with the dominant diatoms of the phytoplankton assemblage, and bacteria isolated from the phytoplankton showed elevated temperatures of crystallization (Tc) as high as ?3?C. Ice nucleation-active bacteria were identified as belonging to the genus Pseudomonas, but we could not demonstrate that they were sufficiently abundant to incite the observed freezing. Regardless of the source of ice nucleation activity, the resulting production of frazil ice may provide a means for the diatoms to be recruited to the overlying lake ice, thereby increasing their fitness. Bacterial epiphytes are likewise expected to benefit from their association with the diatoms as recipients of organic carbon excreted by their hosts. This novel mechanism illuminates a previously undescribed stage of the life cycle of the meroplanktonic diatoms that bloom in Lake Erie and other Great Lakes during winter and offers a model relevant to aquatic ecosystems having seasonal ice cover around the world. PMID:23552624

  7. Copepod Population-Specific Response to a Toxic Diatom Diet

    PubMed Central

    Lauritano, Chiara; Carotenuto, Ylenia; Miralto, Antonio; Procaccini, Gabriele; Ianora, Adrianna

    2012-01-01

    Diatoms are key phytoplankton organisms and one of the main primary producers in aquatic ecosystems. However, many diatom species produce a series of secondary metabolites, collectively termed oxylipins, that disrupt development in the offspring of grazers, such as copepods, that feed on these unicellular algae. We hypothesized that different populations of copepods may deal differently with the same oxylipin-producing diatom diet. Here we provide comparative studies of expression level analyses of selected genes of interest for three Calanus helgolandicus populations (North Sea, Atlantic Ocean and Mediterranean Sea) exposed to the same strain of the oxylipin-producing diatom Skeletonema marinoi using as control algae the flagellate Rhodomonas baltica. Expression levels of detoxification enzymes and stress proteins (e.g. glutathione S-transferase, glutathione synthase, superoxide dismutase, catalase, aldehyde dehydrogenases and heat shock proteins) and proteins involved in apoptosis regulation and cell cycle progression were analyzed in copepods after both 24 and 48 hours of feeding on the diatom or on a control diet. Strong differences occurred among copepod populations, with the Mediterranean population of C. helgolandicus being more susceptible to the toxic diet compared to the others. This study opens new perspectives for understanding copepod population-specific responses to diatom toxins and may help in underpinning the cellular mechanisms underlying copepod toxicity during diatom blooms. PMID:23056617

  8. Diatom assemblages promote ice formation in large lakes.

    PubMed

    D'souza, N A; Kawarasaki, Y; Gantz, J D; Lee, R E; Beall, B F N; Shtarkman, Y M; Koer, Z A; Rogers, S O; Wildschutte, H; Bullerjahn, G S; McKay, R M L

    2013-08-01

    We present evidence for the directed formation of ice by planktonic communities dominated by filamentous diatoms sampled from the ice-covered Laurentian Great Lakes. We hypothesize that ice formation promotes attachment of these non-motile phytoplankton to overlying ice, thereby maintaining a favorable position for the diatoms in the photic zone. However, it is unclear whether the diatoms themselves are responsible for ice nucleation. Scanning electron microscopy revealed associations of bacterial epiphytes with the dominant diatoms of the phytoplankton assemblage, and bacteria isolated from the phytoplankton showed elevated temperatures of crystallization (T(c)) as high as -3 C. Ice nucleation-active bacteria were identified as belonging to the genus Pseudomonas, but we could not demonstrate that they were sufficiently abundant to incite the observed freezing. Regardless of the source of ice nucleation activity, the resulting production of frazil ice may provide a means for the diatoms to be recruited to the overlying lake ice, thereby increasing their fitness. Bacterial epiphytes are likewise expected to benefit from their association with the diatoms as recipients of organic carbon excreted by their hosts. This novel mechanism illuminates a previously undescribed stage of the life cycle of the meroplanktonic diatoms that bloom in Lake Erie and other Great Lakes during winter and offers a model relevant to aquatic ecosystems having seasonal ice cover around the world. PMID:23552624

  9. Diatom feeding across trophic guilds in tidal flat nematodes, and the importance of diatom cell size

    NASA Astrophysics Data System (ADS)

    Moens, Tom; Vafeiadou, Anna-Maria; De Geyter, Ellen; Vanormelingen, Pieter; Sabbe, Koen; De Troch, Marleen

    2014-09-01

    We examine the capacity of nematodes from three feeding types (deposit feeder, epistrate feeder, predator) to utilize microphytobenthos (MPB), and assess whether diatom cell size and consumer body size are important drivers of their feeding. We analyzed natural stable isotope ratios of carbon and nitrogen in abundant nematode genera and a variety of carbon sources at an estuarine intertidal flat. All nematodes had ?13C indicating that MPB is their major carbon source. ?15N, however, demonstrated that only one deposit and one epistrate feeder genus obtained most of their carbon from direct grazing on MPB, whereas other deposit feeders and predators obtained at least part of their carbon by predation on MPB grazers. We then performed a microcosm experiment in which equal cell numbers of each of three differently sized strains of the pennate diatom Seminavis were offered as food to four, one and one genera of deposit feeders, epistrate feeders and predators, respectively. Previous studies have shown that all but the epistrate feeder ingest whole diatoms, whereas the epistrate feeder pierces cells and sucks out their contents. Most genera showed markedly higher carbon absorption from medium and large cells than from small ones. When considering the number of cells consumed, however, none of the nematodes which ingest whole cells exhibited a clear preference for any specific diatom size. The epistrate feeder was the smallest nematode taxon considered here, yet it showed a marked preference for large cells. These results highlight that the feeding mechanism is much more important than consumer size as a driver of particle size selection in nematodes grazing MPB.

  10. The structural response of unsymmetrically laminated composite cylinders

    NASA Technical Reports Server (NTRS)

    Butler, T. A.; Hyer, M. W.

    1989-01-01

    The responses of an unsymmetrically laminated fiber-reinforced composite cylinder to an axial compressive load, a torsional load, and the temperature change associated with cooling from the processing temperature to the service temperature are investigated. These problems are considered axisymmetric and the response is studied in the context of linear elastic material behavior and geometrically linear kinematics. Four different laminates are studied: a general unsymmetric laminate; two unsymmetric but more conventional laminates; and a conventional quasi-isotropic symmetric laminate. The responses based on closed-form solutions for different boundary conditions are computed and studied in detail. Particular emphasis is directed at understanding the influence of elastic couplings in the laminates. The influence of coupling decreased from a large effect in the general unsymmetric laminate, to practically no effect in the quasi-isotropic laminate. For example, the torsional loading of the general unsymmetric laminate resulted in a radial displacement. The temperature change also caused a significant radial displacement to occur near the ends of the cylinder. On the other hand, the more conventional unsymmetric laminate and the quasi-isotropic cylinder did not deform radially when subjected to a torsional load. From the results obtained, it is clear the degree of elastic coupling can be controlled and indeed designed into a cylinder, the degree and character of the coupling being dictated by the application.

  11. A quantitative review of the Cenozoic diatom deposition history

    NASA Astrophysics Data System (ADS)

    Renaudie, Johan; Lazarus, David B.

    2014-05-01

    Marine planktonic diatoms play an important role today as one of the world's main primary producers, as the main organic carbon exporter to the deep sea and also as the main silica exporter balancing global chemical weathering. They were however a very minor component of the plankton at the beginning of the Cenozoic. Studies to date have focussed mainly on the evolution of their taxonomic diversity. Studies of changes in their actual global abundance over the Cenozoic are few, qualitative, and based on limited amounts of data. Reviewing their depositional pattern during the Cenozoic is therefore of interest in order to understand the modality, the context and, eventually, the cause of their rise; and to understand how diatom evolution affected the Cenozoic functioning of the ocean pump. We present here, based on a review of the literature coupled with a new data analysis of the full global ODP-DSDP Initial Reports smear slides descriptions, a quantitative synthesis of the depositional history of marine diatoms for the last 60 Myr. We also place these data in their paleogeographical context in order to understand the changes in diatom biogeography and what it says about Cenozoic paleoceanography. Diatoms first became widespread during the Middle Eocene. Two temporary major high-abundance events, one at the Eocene-Oligocene transition, another during the Late Oligocene were followed by decreases in the Middle Oligocene and Early Miocene. Diatom abundance in sediments shifted in the Mid-Miocene to globally higher values which have largely persisted to the modern day. Despite appearing initially during the Late Oligocene, the Southern Ocean circumpolar diatom accumulation belt only became a stable feature in the Mid-Miocene. At this time the main diatom deposition loci switched from the Atlantic to the Pacific and Indian Oceans, and mid-latitude upwelling zones appeared. Our findings provide support for the idea that diatoms, through their ecological role in the ocean's carbon pump, are responsible at least in part for Cenozoic changes in atmospheric carbon dioxide pressure and therefore changes in global climate state. Additionally, correlations between diatom abundance peaks and shifts in seawater strontium and osmium isotope composition hint at a strong control of weathering on diatom deposition and therefore indicates that diatom abundance can be useful to reconstruct Cenozoic history of weathering intensity.

  12. Direct observations of the mass flocculation of diatom blooms: characteristics, settling velocities and formation of diatom aggregates

    NASA Astrophysics Data System (ADS)

    Alldredge, A. L.; Gotschalk, C. C.

    1989-02-01

    Blooms of chain-forming marine diatoms were observed in the process of aggregating into centimeter-sized flocs of marine snow in surface waters of the Santa Barbara Channel, California. These aggregates were composed of a rich assemblage of living, actively photosynthesizing diatoms dominated by the setose genus Chaetoceros and by chain-forming Nitzschia spp. Flocculation of one bloom occurred in as little as 24 h, and bloom flocculation apparently was not triggered by nitrogen-limitation. Marine snow of diatom origin was also abundant during spring, summer and early autumn throughout the Southern California Bight, suggesting that diatom flocculation is a seasonally significant source of marine snow. Resting spores rarely occurred within either newly formed or aged diatom flocs. The mean in situ settling velocity ( S.D.) of newly formed flocs was 117 56 m d -1, two orders of magnitude faster than unaggregated Chaetoceros. Rapid, episodic export of surface-derived primary production to the ocean bottom via mass flocculation and settlement of diatom blooms can occur prior to consumption by pelagic grazers and significantly effects marine food webs, oceanic flux processes, and diatom biology.

  13. Thermomechanical postbuckling analysis of laminated composite shells

    NASA Technical Reports Server (NTRS)

    Averill, R. C.; Reddy, J. N.

    1993-01-01

    The nonlinear response of laminated composite structures subjected to thermal loads is investigated. Analysis is performed using a refined theory and an associated finite element model for geometrically nonlinear analysis of laminated composite shell structures. The model is based on a third-order displacement field which accounts for both transverse shear and transverse normal deformations. Numerical studies of simply-supported plates and cylindrical panels indicate that when the panels are free to expand or contract in the transverse direction, the predicted critical buckling temperatures do not depend significantly upon whether or not transverse normal deformations are explicitly accounted for in the analysis model. However, the critical buckling temperatures are strongly dependent upon whether or not the transverse normal deformations are restrained along the boundaries of the panels.

  14. Investigating Delamination Migration in Composite Tape Laminates

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.; DeCarvalho, Nelson V.

    2014-01-01

    A modification to a recently developed test specimen designed to investigate migration of a delamination between neighboring ply interfaces in tape laminates is presented. The specimen is a cross-ply laminated beam consisting of 40 plies with a polytetrafluoroethylene insert spanning part way along its length. The insert is located between a lower 0-degree ply (specimen length direction) and a stack of four 90-degree plies (specimen width direction). The modification involved a stacking sequence that promotes stable delamination growth prior to migration, and included a relocation of the insert from the specimen midplane to the interface between plies 14 and 15. Specimens were clamped at both ends onto a rigid baseplate and loaded on their upper surface via a piano hinge assembly, resulting in a predominantly flexural loading condition. Tests were conducted with the load-application point positioned at various locations along a specimen's span. This position affected the sequence of damage events during a test.

  15. X-ray lasing in diatomic molecules

    NASA Astrophysics Data System (ADS)

    Kimberg, Victor; Zhang, Song Bin; Rohringer, Nina

    2014-04-01

    We predict high-gain x-ray lasing in diatomic molecules by ultrafast core ionization of the C K- and O K-edges in CO and the N K-edge in N2 with an x-ray free-electron laser source. To estimate the spectral and temporal output of this molecular x-ray laser, we solve generalized Maxwell-Bloch equations, keeping track of the electronic and nuclear degrees of freedom. Despite the broad fluorescence bandwidth, the amplified x-ray emission shows a narrow spectrum. By controlling the molecular alignment and thereby the alignment of the transition dipole moment polarization and emission energy control of the x-ray laser radiation is achievable.

  16. X-ray lasing in diatomic molecules

    NASA Astrophysics Data System (ADS)

    Kimberg, Victor; Rohringer, Nina

    2014-04-01

    We predict high-gain x-ray lasing in diatomic molecules by ultrafast core ionization of the C K- and O K-edges in CO and the N K-edge in N2 with an x-ray free-electron laser source. We solve generalized Maxwell-Bloch equations, keeping track of the electronic and nuclear degrees of freedom. By controlling the molecular alignment and thereby the alignment of the transition dipole moment polarization control of the emitted x-ray radiation is achievable. Despite the broad fluorescence bandwidth, the amplified x-ray emission shows a narrow spectrum. Preparing the initial vibrational quantum state, the x-ray emission frequency can be tuned within the fluorescence band.

  17. Relationships between dipole moments of diatomic molecules.

    PubMed

    Hou, Shilin; Bernath, Peter F

    2015-02-14

    The dipole moment is one of the most important physical properties of a molecule. We present a combination rule for the dipole moments of related diatomic molecules. For molecules AB, AX, BY, and XY from two different element groups in the periodic table, if their elements make a small parallelogram, reliable predictions can be obtained. Our approach is particularly useful for systems with heavy atoms. For a large set of molecules tested, the average difference of the prediction from experimental data is less than 0.2 debye (D). The dipole moments for heavy molecules such as GaCl, InBr, SrCl, and SrS, for which no experimental data are available at present, are predicted to be 3.17, 3.76, 3.85 and 11.54 D, respectively. PMID:25588998

  18. Free vibration of moving laminated composite plates

    Microsoft Academic Search

    S. Hatami; M. Azhari; M. M. Saadatpour

    2007-01-01

    Two-dimensional axially moving materials have a wide range of industrial applications such as papers, plastics and composites in producing lines, power transmission and conveyor belts, etc. In many of these instances, the moving material is not isotropic, but is a single-layer orthotropic material or consists of several orthotropic layers.In this article, free vibration of axially moving symmetrically laminated plates subjected

  19. Behavior of bolted joints in composite laminates

    Microsoft Academic Search

    Jurf

    1986-01-01

    This investigation characterizes bolted joint strength in Kevlar\\/epoxy and graphite\\/epoxy (0\\/45\\/90\\/-45) composite laminates. The fundamental problem of a single bolt hole loaded symmetrically in tension is addressed. The first objective is to generalize the relationships between width, edge distance, hole size, thickness, washer diameter, and degree of lateral constraint with bolted joint strength based on experimental observations. The second objective

  20. Static contact crushing of composite laminated shells

    Microsoft Academic Search

    C. H. Huang; Y. J. Lee

    2004-01-01

    The crush behavior of carbon-epoxy composite laminated shells with three different curvatures is investigated. The FEM package ABAQUS and the user-defined material subroutine (UMAT) based on the concept of progressive stiffness degradation were employed to simulate crushing until the specimens totally collapsed. The 2-D delamination propagation proposed by Davies et al. is considered to be an additional failure mechanism for

  1. Laminated grid and web magnetic cores

    DOEpatents

    Sefko, John (Monroeville, PA); Pavlik, Norman M. (Plum Borough, PA)

    1984-01-01

    A laminated magnetic core characterized by an electromagnetic core having core legs which comprise elongated apertures and edge notches disposed transversely to the longitudinal axis of the legs, such as high reluctance cores with linear magnetization characteristics for high voltage shunt reactors. In one embodiment the apertures include compact bodies of microlaminations for more flexibility and control in adjusting permeability and/or core reluctance.

  2. The dilemma of disappearing diatoms: Incorporating diatom dissolution data into palaeoenvironmental modelling and reconstruction

    NASA Astrophysics Data System (ADS)

    Ryves, David B.; Battarbee, Richard W.; Fritz, Sherilyn C.

    2009-01-01

    Taphonomic issues pose fundamental challenges for Quaternary scientists to recover environmental signals from biological proxies and make accurate inferences of past environments. The problem of microfossil preservation, specifically diatom dissolution, remains an important, but often overlooked, source of error in both qualitative and quantitative reconstructions of key variables from fossil samples, especially those using relative abundance data. A first step to tackling this complex issue is establishing an objective method of assessing preservation (here, diatom dissolution) that can be applied by different analysts and incorporated into routine counting strategies. Here, we establish a methodology for assessment of diatom dissolution under standard light microscopy (LM) illustrated with morphological criteria for a range of major diatom valve shapes. Dissolution data can be applied to numerical models (transfer functions) from contemporary samples, and to fossil material to aid interpretation of stratigraphic profiles and taphonomic pathways of individual taxa. Using a surface sediment diatom-salinity training set from the Northern Great Plains (NGP) as an example, we explore a variety of approaches to include dissolution data in salinity inference models indirectly and directly. Results show that dissolution data can improve models, with apparent dissolution-adjusted error (RMSE) up to 15% lower than their unadjusted counterparts. Internal validation suggests improvements are more modest, with bootstrapped prediction errors (RMSEP) up to 10% lower. When tested on a short core from Devils Lake, North Dakota, which has a historical record of salinity, dissolution-adjusted models infer higher values compared to unadjusted models during peak salinity of the 1930s-1940s Dust Bowl but nonetheless significantly underestimate peak values. Site-specific factors at Devils Lake associated with effects of lake level change on taphonomy (preservation and re-working, implied by dissolution data) may override model improvements incorporating dissolution. Dissolution-adjusted salinity models are also applied to a 150-year sediment record from Spiritwood Lake, North Dakota, which suggests that this lake has a damped and lagged response to major regional climate forcing of salinity during the Dust Bowl. At this site, dissolution data also suggest different taphonomic behaviour of taxa related to their seasonal patterns of growth and sedimentation. Thus, dissolution data can improve models, and aid interpretation of sedimentary profiles as records of limnological, ecological and environmental change, filtered by taphonomy.

  3. Modeling Composite Laminate Crushing for Crash Analysis

    NASA Technical Reports Server (NTRS)

    Fleming, David C.; Jones, Lisa (Technical Monitor)

    2002-01-01

    Crash modeling of composite structures remains limited in application and has not been effectively demonstrated as a predictive tool. While the global response of composite structures may be well modeled, when composite structures act as energy-absorbing members through direct laminate crushing the modeling accuracy is greatly reduced. The most efficient composite energy absorbing structures, in terms of energy absorbed per unit mass, are those that absorb energy through a complex progressive crushing response in which fiber and matrix fractures on a small scale dominate the behavior. Such failure modes simultaneously include delamination of plies, failure of the matrix to produce fiber bundles, and subsequent failure of fiber bundles either in bending or in shear. In addition, the response may include the significant action of friction, both internally (between delaminated plies or fiber bundles) or externally (between the laminate and the crushing surface). A figure shows the crushing damage observed in a fiberglass composite tube specimen, illustrating the complexity of the response. To achieve a finite element model of such complex behavior is an extremely challenging problem. A practical crushing model based on detailed modeling of the physical mechanisms of crushing behavior is not expected in the foreseeable future. The present research describes attempts to model composite crushing behavior using a novel hybrid modeling procedure. Experimental testing is done is support of the modeling efforts, and a test specimen is developed to provide data for validating laminate crushing models.

  4. Characteristics of laminates with delamination control strips

    NASA Technical Reports Server (NTRS)

    Sun, C. T.; Goering, J. C.; Alper, J. M.; Gause, L. W.

    1992-01-01

    Tough resin is needed to resist delamination crack propagation. However, modulus often has to be compromised because it is difficult to retain both high modulus and toughness in a matrix material. A potential solution is to use a hybrid system in which tough resin strips are included within a conventional matrix composite. By adjusting the spacing of the tough resin strips, maximum delamination size can be controlled. Experimental results for impact damage and subsequent damage propagation in laminates containing tough resin strips are reported. Plain adhesive strips and fiber-reinforced tough resin composite strips were used in constructing the hybrid laminates. Test results indicated that size of delamination inflicted by impact was confined between the tough resin strips. As a result, significantly increased residual compressive strength was obtained. Impacted laminates containing tough resin strips were also fatigue tested. It was found that these strips reduced the growth of the impact damage area relative to the growth seen in coupons with no tough resin strips. Damage growth from an open hole under tension fatigue was evaluated using both tough resin strips and glass fiber reinforced tough resin strips. Unreinforced tough resin strips retarded delamination growth from the open hole, but did not stop matrix cracks growing in the fiber direction. Fiber reinforced tough resin strips did not contain axial delamination growth from the open hole. However, they did act as crack arresters, stopping the through-the-thickness tension crack originating from the hole.

  5. Laminate articles on biaxially textured metal substrates

    DOEpatents

    Beach, David B.; Morrell, Jonathan S.; Paranthaman, Mariappan; Chirayil, Thomas; Specht, Eliot D.; Goyal, Amit

    2003-12-16

    A laminate article comprises a substrate and a biaxially textured (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer over the substrate, wherein 0laminate article can include a layer of YBCO over the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (R.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  6. Scaling effects in angle-ply laminates

    NASA Technical Reports Server (NTRS)

    Kellas, Sotiris; Morton, John

    1992-01-01

    The effect of specimen size upon the response and strength of +/- 45 degree angle-ply laminates was investigated for two graphite fiber reinforced plastic systems and several stacking sequences. The first material system was a brittle epoxy based system, AS4 fibers in 3502 epoxy, and the second was a tough thermoplastic based system, AS4 fibers in PEEK matrix. For the epoxy based system, two generic +/- 45 degree lay-ups were studied: (+45 degrees sub n/-45 degrees sub n) sub 2S (blocked plies), and (+45 degrees/-45 degrees) sub 2nS, for n=1 and 2. The in-plane dimensions of the specimens were varied such that the width/length relationship was 12.7 x n/127 x n mm, for m=1, 2, 3, or 4. It is shown that the stress/strain response and the ultimate strength of these angle-ply laminates depends on the laminate thickness and the type of generic lay-up used. Furthermore, it is shown that first ply failure occurs in the surface plies as a result of normal rather than shear stresses. The implications of the experimental findings upon the validity of the +/- 45 degree tensile test which is used to determine the in-plane shear response of unidirectional composites are discussed.

  7. A theory for predicting composite laminate warpage resulting from fabrication

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1975-01-01

    Linear laminate theory is used in conjunction with the moment-curvature relationship to derive equations for predicting end deflections due to warpage without solving the coupled fourth-order partial differential equations of the plate. Using these equations, it is found that a 1 deg error in the orientation angle of one ply is sufficient to produce warpage end deflection equal to two laminate thicknesses in a 10 inch by 10 inch laminate made from 8-ply Mod-I/epoxy. From a sensitivity analysis on the governing parameters, it is found that a 3 deg fiber migration or a void volume ratio of three percent in some plies is sufficient to produce laminate warpage corner deflection equal to several laminate thicknesses. Tabular and graphical data are presented which can be used to identify possible errors contributing to laminate warpage and/or to obtain an a priori assessment when unavoidable errors during fabrication are anticipated.

  8. A continuum model for damage evolution in laminated composites

    NASA Technical Reports Server (NTRS)

    Lo, D. C.; Allen, D. H.; Harris, C. E.

    1991-01-01

    The accumulation of matrix cracking is examined using continuum damage mechanics lamination theory. A phenomenologically based damage evolutionary relationship is proposed for matrix cracking in continuous fiber reinforced laminated composites. The use of material dependent properties and damage dependent laminate averaged ply stresses in this evolutionary relationship permits its application independently of the laminate stacking sequence. Several load histories are applied to crossply laminates using this model, and the results are compared to published experimental data. The stress redistribution among the plies during the accumulation of matrix damage is also examined. It is concluded that characteristics of the stress redistribution process could assist in the analysis of the progressive failure process in laminated composites.

  9. No microzooplankton grazing during a Mediopyxis helysia dominated diatom bloom

    NASA Astrophysics Data System (ADS)

    Loebl, Martina; van Beusekom, Justus E. E.; Philippart, Catharina J. M.

    2013-09-01

    The new diatom species Mediopyxis helysia was described to science from clones found in 2003 in the North Sea, northern Wadden Sea, and the Gulf of Maine. Seven years after its first occurrence, we observed Mediopyxis to contribute up to almost 50% of the biovolume of the diatoms during a diatom spring bloom in the western Wadden Sea. Grazing experiments based on the dilution technique could not detect any microzooplankton grazing impact on the bloom community. Mediopyxis is now also well established in the western Wadden Sea and does have the potential to become a dominant species. The reasons for its success remain largely unresolved but avoidance of being grazed might be one factor. Future research on this new species is needed to understand the success and forecast the ecological footprint of this large diatom species arriving in the western European Seas.

  10. The Phaeodactylum genome reveals the evolutionary history of diatom genomes

    E-print Network

    Gent, Universiteit

    , Bank Beszteri7 , Ansgar Gruber8 , Marc Heijde1 , Michael Katinka9 , Thomas Mock10 {, Klaus Valentin7 of gene diversification in diatoms. Contributing factors include selective gene family expansions

  11. Modified Ribose Receptor Response in Isolated Diatom Frustules

    SciTech Connect

    Fairbanks, Carly R.

    2011-08-26

    Diatoms are a distinctive group of microalgae with the unique ability to produce a highly-ordered biosilica matrix, known as the frustule. Diatoms hold significant potential in the biotechnology field as a silica scaffold for embedding proteins. In this study, we analyzed the funtionalization of biosilica with a receptor complex through genetic modification of the diatom, Thalassiosira pseudonana. Through the use of Foerster Resonance Energy Transfer (FRET), the receptor was shown to remain active in transformed frustules after the inner cellular contents were removed. In addition to protein functionality, growth conditions for T. pseudonana were optimized. Untransformed cultures receiving aeration grew more rapidly than stagnant untransformed cultures. Surprisingly, transformed cultures grew more quickly than untransformed cultures. This study demonstrates isolated diatom frustules provide an effective scaffold for embedded receptor complexes. Through this research, we provide the groundwork for the development of new biosensors for use in diagnostics and environmental remediation.

  12. Non-linear behavior of fiber composite laminates

    NASA Technical Reports Server (NTRS)

    Hashin, Z.; Bagchi, D.; Rosen, B. W.

    1974-01-01

    The non-linear behavior of fiber composite laminates which results from lamina non-linear characteristics was examined. The analysis uses a Ramberg-Osgood representation of the lamina transverse and shear stress strain curves in conjunction with deformation theory to describe the resultant laminate non-linear behavior. A laminate having an arbitrary number of oriented layers and subjected to a general state of membrane stress was treated. Parametric results and comparison with experimental data and prior theoretical results are presented.

  13. Stiffness degradation induced by multilayer intralaminar cracking in composite laminates

    Microsoft Academic Search

    Junqian Zhang; K. P. Herrmann

    1999-01-01

    A theoretical model for the prediction of the elastic properties of a general symmetric laminate containing multilayer matrix cracks is proposed. A five-layer equivalent constraint model (ECM) laminate [SL\\/?p\\/?q\\/?r\\/SR]s and seven others degenerated from such a model laminate by eliminating some of the sublaminates, [?p],[?r], SL and SR, are designed for the analyses of the degraded stiffnesses of the cracked

  14. Thixoforming of laminate made from semisolid cast strips

    Microsoft Academic Search

    T. Haga; P. Kapranos

    2004-01-01

    In order to reduce the cost of the feedstock, a laminate, in the form of a slug, made from roll cast strips has been used as feedstock for thixoforming. The size of the laminate cube was 40mm40mm40mm. A high-speed twin roll caster was used to cast A356 strip from which the laminate was manufactured. The strip thickness varied from 3mm

  15. Interlaminate Deformation in Thermoplastic Composite Laminates: Experimental-Numerical Correlation

    Microsoft Academic Search

    M. Shen; J. Tong; S. Wang; Y. Fang

    2010-01-01

    The interlaminar deformation behaviors of thermoplastic AS4\\/PEEK composite laminates subjected to static tensile loading are investigated by means of microscopic moir interferometry with high spatial resolution. The fully threedimensional orthotropic elastic-plastic analysis of interlaminar deformation for the thermoplastic laminates is developed in this paper, and used to simulate the stress-strain curves of tensile experiment for its angle-ply laminates. Under uniaxial

  16. Energy Saving Glass Lamination via Selective Radio-Frequency Heating

    SciTech Connect

    Shulman, Holly S.; Allan, Shawn M.

    2009-11-11

    This Inventions and Innovations program supported the technical and commercial research and development needed to elevate Ceralink's energy saving process for flat glass lamination from bench scale to a self-supporting technology with significant potential for growth. Radio-frequency heating was any un-explored option for laminating glass prior to this program. With significant commercial success through time and energy savings in the wood, paper, and plastics industries, RF heating was found to have significant promise for the energy intensive glass lamination industry. A major technical goal of the program was to demonstrate RF lamination across a wide range of laminate sizes and materials. This was successfully accomplished, dispelling many skeptics' concerns about the abilities of the technology. Ceralink laminated panels up to 2 ft x 3 ft, with four sets processed simultaneously, in a 3 minute cycle. All major categories of interlayer materials were found to work with RF lamination. In addition to laminating glass, other materials including photovoltaic silicon solar cells, light emitting diodes, metallized glass, plastics (acrylic and polycarbonate), and ceramics (alumina) were found compatible with the RF process. This opens up a wide range of commercial opportunities beyond the initially targeted automotive industry. The dramatic energy savings reported for RF lamination at the bench scale were found to be maintained through the scale up of the process. Even at 2 ft x 3 ft panel sizes, energy savings are estimated to be at least 90% compared to autoclaving or vacuum lamination. With targeted promotion through conference presentations, press releases and internet presence, RF lamination has gained significant attention, drawing large audiences at American Ceramic Society meetings. The commercialization success of the project includes the establishment of a revenue-generating business model for providing process development and demonstrations for potential RF lamination users. A path to industrial energy benefits and revenue through industrial equipment sales was established in a partnership with Thermex Thermatron, a manufacturer of RF equipment.

  17. Computer checking of rotational line intensity factors for diatomic transitions.

    NASA Technical Reports Server (NTRS)

    Whiting, E. E.; Paterson, J. A.; Kovacs, I.; Nicholls, R. W.

    1973-01-01

    Previously published analytical formulae for the rotational line intensity factors of diatomic molecules have been compared with results from a comprehensive computer program, which determines numerical intensity factors for both spin-allowed and spin-forbidden electric and magnetic dipole transitions in diatomic molecules. The comparison uncovered several typographical errors and a few algebraic errors in the published formulae. The changes required in the formulae to give agreement with the results from the computer program are tabulated.

  18. Diatom frustule photonic crystal geometric and optical characterization

    NASA Astrophysics Data System (ADS)

    Mishler, Jonathan; Blake, Phillip; Alverson, Andrew J.; Roper, D. K.; Herzog, Joseph B.

    2014-08-01

    Diatom algae are single-celled, photosynthetic organisms with a cell wall called a frustulea periodically patterned nano-structure made of silica. Throughout the last decade, diatom frustules have been studied for their potential uses as photonic crystals and biomimetic templates for artificially developed metamaterials. A MATLAB program characterizing their pore structure as a function of angle was developed, potentially giving insight into how their geometric characteristics determine their optical properties.

  19. Mechanical model of blebbing in nuclear lamin meshworks

    PubMed Central

    Funkhouser, Chloe M.; Sknepnek, Rastko; Shimi, Takeshi; Goldman, Anne E.; Goldman, Robert D.; Olvera de la Cruz, Monica

    2013-01-01

    Much of the structural stability of the nucleus comes from meshworks of intermediate filament proteins known as lamins forming the inner layer of the nuclear envelope called the nuclear lamina. These lamin meshworks additionally play a role in gene expression. Abnormalities in nuclear shape are associated with a variety of pathologies, including some forms of cancer and HutchinsonGilford Progeria Syndrome, and often include protruding structures termed nuclear blebs. These nuclear blebs are thought to be related to pathological gene expression; however, little is known about how and why blebs form. We have developed a minimal continuum elastic model of a lamin meshwork that we use to investigate which aspects of the meshwork could be responsible for bleb formation. Mammalian lamin meshworks consist of two types of lamin proteins, A type and B type, and it has been reported that nuclear blebs are enriched in A-type lamins. Our model treats each lamin type separately and thus, can assign them different properties. Nuclear blebs have been reported to be located in regions where the fibers in the lamin meshwork have a greater separation, and we find that this greater separation of fibers is an essential characteristic for generating nuclear blebs. The model produces structures with comparable morphologies and distributions of lamin types as real pathological nuclei. Thus, preventing this opening of the meshwork could be a route to prevent bleb formation, which could be used as a potential therapy for the pathologies associated with nuclear blebs. PMID:23401537

  20. Sound transmission into a laminated composite cylindrical shell

    NASA Technical Reports Server (NTRS)

    Koval, L. R.

    1980-01-01

    In the context of the transmission of airborne noise into an aircraft fuselage, a mathematical model is presented for the transmission of an oblique plane sound wave into a laminated composite circular cylindrical shell. Numerical results are obtained for geometry typical of a narrow-bodied jet transport. Results indicate that from the viewpoint of noise attenuation on laminated composite shell does not appear to offer any significant advantage over an aluminum shell. However, the transmission loss of a laminated composite shell is sensitive to the orientation of the fibers and this suggests the possibility of using a laminated composite shell to tailor the noise attenuation characteristics to meet a specific need.

  1. Biochemical and Molecular Genetic Studies on Biosilica Morphogenesis in Diatoms

    NASA Astrophysics Data System (ADS)

    Kroger, N.; Poulsen, N.

    2006-12-01

    Diatoms are a large group of unicellular microalgae encased by silica cell walls that exhibit species-specific micro-and nanopatterns. Previously, we have characterized from diatoms unique phosphoproteins (termed silaffins) and unusually long polyamine chains (termed LCPA), which have both been implicated in biosilica formation. While the chemical structures of LCPA are largely conserved among different diatom species, the silaffins exhibit extensive structural variations. In vitro studies on the silica formation activities of silaffins and LCPA from the diatom Thalassiosira pseudonana indicate that silica morphogenesis is primarily determined by silaffins rather than LCPA. Recently, the complete genome sequence of T. pseudonana has become available, which for the first time opens the door to employ functional genomic approaches for studying the mechanism of silica biomineralization. To this end we have established the first genetic transformation system for T. pseudonana, which will be instrumental for analyzing the functions of silaffins in vivo, and for identifying new components of the diatom silica forming machinery. Here we describe the current knowledge on the structures and properties of silaffins and LCPA, the methods for genetic manipulation of T. pseudonana, and the first experimental steps towards functional genomics in diatoms.

  2. Environmental factors influencing diatom communities in Antarctic cryoconite holes

    NASA Astrophysics Data System (ADS)

    Stanish, L. F.; Bagshaw, E. A.; McKnight, D. M.; Fountain, A. G.; Tranter, M.

    2013-12-01

    Cryoconite holes are ice-bound habitats that can act as refuges for aquatic and terrestrial microorganisms on glacier surfaces. In the McMurdo Dry Valleys of Antarctica, these holes are often capped by an ice lid that prevents the exchange of material and gases with the surrounding atmosphere and aquatic environment. Diatoms have been documented in cryoconite holes, and recent findings suggest that these habitats may harbour a distinctive diatom flora compared to the surrounding aquatic environments. In this study, we examined diatom community composition in cryoconite holes and environmental correlates across three glaciers in Taylor Valley, Antarctica. The diatom communities were dominated by two genera, Muelleria and Diadesmis, both of which had high viability and could have been seeded from the surrounding ephemeral streams. The location of the cryoconite hole within the valley was a key determinant of community composition. A diatom species richness gradient was observed that corresponded to distance inland from the coast and co-varied with species richness in streams within the same lake basin. Cryoconite holes that were adjacent to streams with higher diversity displayed greater species richness. However, physical factors, such as the ability to withstand freeze-thaw conditions and to colonize coarse sediments, acted as additional selective filters and influenced diatom diversity, viability and community composition.

  3. Marine Polysaccharide Networks and Diatoms at the Nanometric Scale

    PubMed Central

    Svetli?i?, Vesna; uti?, Vera; Pletikapi?, Galja; Radi?, Tea Mii?

    2013-01-01

    Despite many advances in research on photosynthetic carbon fixation in marine diatoms, the biophysical and biochemical mechanisms of extracellular polysaccharide production remain significant challenges to be resolved at the molecular scale in order to proceed toward an understanding of their functions at the cellular level, as well as their interactions and fate in the ocean. This review covers studies of diatom extracellular polysaccharides using atomic force microscopy (AFM) imaging and the quantification of physical forces. Following a brief summary of the basic principle of the AFM experiment and the first AFM studies of diatom extracellular polymeric substance (EPS), we focus on the detection of supramolecular structures in polysaccharide systems produced by marine diatoms. Extracellular polysaccharide fibrils, attached to the diatom cell wall or released into the surrounding seawater, form distinct supramolecular assemblies best described as gel networks. AFM makes characterization of the diatom polysaccharide networks at the micro and nanometric scales and a clear distinction between the self-assembly and self-organization of these complex systems in marine environments possible. PMID:24113585

  4. Molecular Fossils as Time Indicators for the Evolution of Diatoms.

    NASA Astrophysics Data System (ADS)

    Rampen, S. W.; Schouten, S.; Muyzer, G.; Abbas, B.; Rowland, S. J.; Moldowan, M.; Sinninghe Damst, J. S.

    2004-12-01

    Bacillariophyta (diatoms) are one of the most abundant divisions of phytoplankton, and contribute to almost 50% of the primary productivity of today's oceans. However, their ecological dominance is relatively young and little is known about the exact pace of their rapid evolution. DNA analyses on diatoms and the use of molecular clock calculations can help to reconstruct their evolution, but this molecular clock rate needs to be calibrated against the fossil record to determine the mutation rate. Until now, diatom silica skeletons have been used for reconstructing the evolution of diatoms, but their use is limited due to destruction by diagenesis. Molecular fossils may prove to be more useful for time reconstruction. To search for suitable compounds, we have analyzed both the lipid composition and 18S rRNA sequences of ca. 100 marine diatoms. This revealed that some specific phylogenetic clusters within the diatoms produce specific organic compounds, so-called diatom biomarkers. One group of diatom biomarkers are the C25 highly branched isoprenoid (HBI) alkenes (1,2). HBI biosynthesis evolved independently at least twice in the diatoms. The first group of HBI producers consists of the centric diatoms of the genus Rhizosolenia, the second group comprises pennate diatoms of the genera Haslea, Navicula and Pleurosigma. Based on the constructed phylogenetic tree it is likely that the HBI biosynthesis evolved first in the older group of centric diatoms (i.e. the Rhizosolenia genus). The fossil record was studied to determine the geological occurrence of C25 HBI alkenes, and this data set shows that HBI biosynthesis evolved ca. 91.5 My ago, so we can date the evolution of the genus Rizosolenia to ca. 91.5 My. With this information, we can now accurately predict the mutation rate of the 18S rDNA gene to 1% per 14.8 My for Rhizosolenia, which is substantially faster than the 1% per 18-26 My reported previously for diatoms in general. Another specific biomarker is 24-norsterol. Its value as an age diagnostic biomarker was already reported (3), but the source of this sterol was still unknown although a diatomaceous source was assumed. We have now found this sterol in the diatom species Thalassiosira aff. Antarctica. In combination with the knowledge that the 24-norsterol production increased substantially during the Cretaceous this may provide a tool to predict the mutation rate of the Thalassiosirales. Our data show that molecular paleontology can assist in obtaining more reliable estimates of the molecular clock rate and thus be an important tool in reconstructing the evolution of diatoms. References: 1. J.K. Volkman et al., Org.Geochem. 21, 407-413 (1994). 2. J.S. Sinninghe Damst et al., Science 304, 584-587 (2004). 3. A.G. Holba et al., Org.Geochem. 29, 1269-1283 (1998).

  5. Nuclear lamina heterogeneity in mammalian cells. Differential expression of the major lamins and variations in lamin B phosphorylation.

    PubMed

    Worman, H J; Lazaridis, I; Georgatos, S D

    1988-08-25

    We have studied the molecular composition of the nuclear lamina in rat tissues of distinct embryological origin and the occurrence of the nuclear lamins during in vitro differentiation of the mouse F9 teratocarcinoma cell line. Immunochemical analysis demonstrated that all rat tissues contained the three major lamin forms (lamins A, B, and C) previously recognized in rat liver nuclei; however, other minor cross-reactive components were also identified in some tissues. The amount of the 67-kDa lamin B complexed with lamins A and C in the laminae of different tissues ranged from a stoichiometry of much less than 1 to approximately 1. Furthermore, it was found that F9 stem cells and their differentiated progeny express only lamin B, and Northern blotting analysis indicated that these cells fail to accumulate lamin A and C mRNA. Chemical cleavages and peptide mapping suggested that the 67-kDa lamin B form was of similar primary structure in all differentiated tissues and F9 cells. Employing antibodies with different affinities for phosphorylated and nonphosphorylated lamin B, we showed that the apparent invariance in the expression of this polypeptide is overriden by a heterogeneity produced via tissue-specific phosphorylation. Because similar differences in antibody recognition could be reproduced in vitro by phosphorylating lamin B with protein kinase A, we have concluded that the tissue-specific modifications of this protein may occur at consensus sites recognized by this enzyme. These data support the hypotheses that the lamins can form functional laminae by associating at various combinations, and that processes including differential lamin synthesis and post-translational modification can produce a steady state lamina heterogeneity. PMID:3403563

  6. Bacteria Associated with Benthic Diatoms from Lake Constance: Phylogeny and Influences on Diatom Growth and Secretion of Extracellular Polymeric Substances?

    PubMed Central

    Bruckner, Christian G.; Bahulikar, Rahul; Rahalkar, Monali; Schink, Bernhard; Kroth, Peter G.

    2008-01-01

    The composition of diatom-associated bacterial communities was studied with 14 different unialgal xenic diatom cultures isolated from freshwater epilithic biofilms of Lake Constance, Germany. A clear dominance of Alphaproteobacteria was observed, followed by Betaproteobacteria, Gammaproteobacteria, Bacteroidetes, and Verrucomicrobia. Pure cultures of the diatom Cymbella microcephala, which was found to be dominant in epilithic biofilms in Lake Constance, were cocultivated with six associated bacterial strains. All these bacterial strains were able to grow in C. microcephala cultures in the absence of organic cosubstrates. Diatom growth was generally enhanced in the presence of bacteria, and polysaccharide secretion was generally increased in the presence of Proteobacteria. The monomer composition of extracellular polysaccharides of C. microcephala changed in relation to the presence of different bacteria, but the dominant monomers were less affected. Our results indicate that these changes were caused by the diatom itself rather than by specific bacterial degradation. One Bacteroidetes strain strongly influenced carbohydrate secretion by the alga via extracellular soluble compounds. Biofilms were formed only in the presence of bacteria. Phylogenetic analysis and coculture studies indicate an adaptation of Proteobacteria and Bacteroidetes to the microenvironment created by the diatom biofilm. PMID:18931294

  7. Species-dependent silicon isotope fractionation by marine diatoms

    NASA Astrophysics Data System (ADS)

    Sutton, Jill N.; Varela, Diana E.; Brzezinski, Mark A.; Beucher, Charlotte P.

    2013-03-01

    Fractionation of silicon (Si) isotopes was measured in seven species (nine strains) of polar and sub-polar marine diatoms grown in semi-continuous unialgal cultures under optimal irradiance and temperature for each diatom strain. Results from this work provide the first evidence that Si isotope fractionation by diatoms is species-dependent. The greatest difference in the Si isotope fractionation factor (?) was observed between two Southern Ocean diatoms, Fragilariopsis kerguelensis (-0.54, average for two strains) and Chaetoceros brevis (-2.09). The ? for the other species, both polar and sub-polar, ranged from -0.72 to -1.21. The two remaining polar diatoms had ? values of -0.74 0.05 for Thalassiosira antarctica, and -1.21 0.04 for Thalassiosira nordenskioeldii, while the sub-polar species had ? values of -0.72 0.04 for Thalassiosira weissflogii, -0.88 0.06 for Thalassiosira pseudonana (CCCM58), -0.97 0.14 for Thalassiosira pseudonana (CCMP1014), and -1.15 0.03 for Porosira glacialis. The range in ? for the diatoms evaluated in this study may be large enough to significantly impact the Si isotope composition measured in diatom opal (?30Si-bSiO2) from marine sediments and its subsequent interpretation. To test the influence of diatom taxonomic composition on ?30Si-bSiO2, we developed a model that considered the relative abundance of diatom species and the ? values (from this study) for each species present within the sediment core (i.e. weighted-average ?). The model was applied to records from a Southern Ocean sediment core (TN057-13) where both diatom abundance and ?30Si-bSiO2 data were available. The analysis indicated that 67% of the variation in ?30Si-bSiO2 could be explained by species-dependent Si isotope fractionation. We suggest that future work should assess phytoplankton taxonomic composition when using ?30Si-bSiO2 as a proxy for Si utilization.

  8. Seasonal changes of diatom species in the Hooghly estuary, India

    NASA Astrophysics Data System (ADS)

    Goswami, P. K.

    2013-12-01

    The Hooghly estuary is considered as one of the most important fishing ground of north-east India which is mainly because presence of large shallow parts of Bays, which provide extensive growths for benthic and planktonic community and also makes it a highly productive area .Anthropogenic effects induce intensive pressure to this ecosystem ;and consequently results in the eutrophication followed by rapid plankton growth, sometimes even bloom. Diatom comprises one of the most diverse and significant part of the biota of aquatic habitats. Ecologically they are of immense importance since they constitute the podium of food chain and are at pinnacle of the biomass pyramid. The present study was based on the diversity of most dominant diatom species found in the brackish waters of Hooghly estuarine region in three locations of Sagar islands - Gangasagar, Chemaguri and Kachuberia. In this study diatom distribution from post monsoon - pre monsoon period was studied on the specific assemblages of them.. There was wide diversity of diatom species in different locations and in different seasons. Maximum number of diatom species was found in post-monsoon period in Gangasagar and Chemaguri, while in Kachuberia maximum number was found in pre-monsoon period. In Gangasagar, Navicula socialis, Coscinodiscus spp. and Biddulphia spp. were the predominant species in early, mid and late post monsoon period respectively and Biddulphia spp. also continues as the predominant diatom in pre-monsoon period. In Chemaguri, Amphora ostrearia, Coscinodiscus perforatus and Nitzschia acuminate were the predominant species in early, mid and late post monsoon period respectively while Coscinodiscus radiates was the stable predominant diatom species in pre-monsoon period while Thalassionema spp., Ditylum spp., Proboscia spp. and Biddulphia spp. were also found in significantly increased numbers at different times of pre-monsoon period. In Kachuberia area although a wide range of diatoms are present in post-monsoon period it was Coscinodiscus radiates which was the single predominant species found in total pre-monsoon period. Although such changes of diatom species in different seasons may be due to influence of various factors but seasonal changes may be the major factor influencing such changes of diatom species in this area.

  9. Vibrational Excitation of Diatomic Molecular Ions in Strong Field Ionization of Diatomic Molecules

    SciTech Connect

    Kjeldsen, Thomas K.; Madsen, Lars Bojer [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark)

    2005-08-12

    A model based on the strong-field and Born-Oppenheimer approximations qualitatively describes the distribution over vibrational states formed in a diatomic molecular ion following ionization of the neutral molecule by intense laser pulses. Good agreement is found with a recent experiment [X. Urbain et al., Phys. Rev. Lett. 92, 163004 (2004)]. In particular, the observed deviation from a Franck-Condon-like distribution is reproduced. Additionally, we demonstrate control of the vibrational distribution by a variation of the peak intensity or a change of frequency of the laser pulse.

  10. Nanopatterned protein microrings from a diatom that direct silica morphogenesis.

    PubMed

    Scheffel, Andr; Poulsen, Nicole; Shian, Samuel; Krger, Nils

    2011-02-22

    Diatoms are eukaryotic microalgae that produce species-specifically structured cell walls made of SiO(2) (silica). Formation of the intricate silica structures of diatoms is regarded as a paradigm for biomolecule-controlled self-assembly of three-dimensional, nano- to microscale-patterned inorganic materials. Silica formation involves long-chain polyamines and phosphoproteins (silaffins and silacidins), which are readily soluble in water, and spontaneously form dynamic supramolecular assemblies that accelerate silica deposition and influence silica morphogenesis in vitro. However, synthesis of diatom-like silica structure in vitro has not yet been accomplished, indicating that additional components are required. Here we describe the discovery and intracellular location of six novel proteins (cingulins) that are integral components of a silica-forming organic matrix (microrings) in the diatom Thalassiosira pseudonana. The cingulin-containing microrings are specifically associated with girdle bands, which constitute a substantial part of diatom biosilica. Remarkably, the microrings exhibit protein-based nanopatterns that closely resemble characteristic features of the girdle band silica nanopatterns. Upon the addition of silicic acid the microrings become rapidly mineralized in vitro generating nanopatterned silica replicas of the microring structures. A silica-forming organic matrix with characteristic nanopatterns was also discovered in the diatom Coscinodiscus wailesii, which suggests that preassembled protein-based templates might be general components of the cellular machinery for silica morphogenesis in diatoms. These data provide fundamentally new insight into the molecular mechanisms of biological silica morphogenesis, and may lead to the development of self-assembled 3D mineral forming protein scaffolds with designed nanopatterns for a host of applications in nanotechnology. PMID:21300899

  11. Distinctive photosystem II photoinactivation and protein dynamics in marine diatoms.

    PubMed

    Wu, Hongyan; Cockshutt, Amanda M; McCarthy, Avery; Campbell, Douglas A

    2011-08-01

    Diatoms host chlorophyll a/c chloroplasts distinct from green chloroplasts. Diatoms now dominate the eukaryotic oceanic phytoplankton, in part through their exploitation of environments with variable light. We grew marine diatoms across a range of temperatures and then analyzed their PSII function and subunit turnover during an increase in light to mimic an upward mixing event. The small diatom Thalassiosira pseudonana initially responds to increased photoinactivation under blue or white light with rapid acceleration of the photosystem II (PSII) repair cycle. Increased red light provoked only modest PSII photoinactivation but triggered a rapid clearance of a subpool of PsbA. Furthermore, PsbD and PsbB content was greater than PsbA content, indicating a large pool of partly assembled PSII repair cycle intermediates lacking PsbA. The initial replacement rates for PsbD (D2) were, surprisingly, comparable to or higher than those for PsbA (D1), and even the supposedly stable PsbB (CP47) dropped rapidly upon the light shift, showing a novel aspect of rapid protein subunit turnover in the PSII repair cycle in small diatoms. Under sustained high light, T. pseudonana induces sustained nonphotochemical quenching, which correlates with stabilization of PSII function and the PsbA pool. The larger diatom Coscinodiscus radiatus showed generally similar responses but had a smaller allocation of PSII complexes relative to total protein content, with nearly equal stiochiometries of PsbA and PsbD subunits. Fast turnover of multiple PSII subunits, pools of PSII repair cycle intermediates, and photoprotective induction of nonphotochemical quenching are important interacting factors, particularly for small diatoms, to withstand and exploit high, fluctuating light. PMID:21617029

  12. Cenozoic planktonic marine diatom diversity and correlation to climate change.

    PubMed

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Trke, Andreas

    2014-01-01

    Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ?(18)O (climate) and carbon cycle records (?(13)C, and 20-0 Ma pCO2). Warmer climates are strongly correlated with lower diatom diversity (raw: rho?=?.92, p<.001; detrended, r?=?.6, p?=?.01). Diatoms were 20% less diverse in the early late Miocene, when temperatures and pCO2 were only moderately higher than today. Diversity is strongly correlated to both ?(13)C and pCO2 over the last 15 my (for both: r>.9, detrended r>.6, all p<.001), but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls. PMID:24465441

  13. Nanopatterned protein microrings from a diatom that direct silica morphogenesis

    PubMed Central

    Scheffel, Andr; Poulsen, Nicole; Shian, Samuel; Krger, Nils

    2011-01-01

    Diatoms are eukaryotic microalgae that produce species-specifically structured cell walls made of SiO2 (silica). Formation of the intricate silica structures of diatoms is regarded as a paradigm for biomolecule-controlled self-assembly of three-dimensional, nano- to microscale-patterned inorganic materials. Silica formation involves long-chain polyamines and phosphoproteins (silaffins and silacidins), which are readily soluble in water, and spontaneously form dynamic supramolecular assemblies that accelerate silica deposition and influence silica morphogenesis in vitro. However, synthesis of diatom-like silica structure in vitro has not yet been accomplished, indicating that additional components are required. Here we describe the discovery and intracellular location of six novel proteins (cingulins) that are integral components of a silica-forming organic matrix (microrings) in the diatom Thalassiosira pseudonana. The cingulin-containing microrings are specifically associated with girdle bands, which constitute a substantial part of diatom biosilica. Remarkably, the microrings exhibit protein-based nanopatterns that closely resemble characteristic features of the girdle band silica nanopatterns. Upon the addition of silicic acid the microrings become rapidly mineralized in vitro generating nanopatterned silica replicas of the microring structures. A silica-forming organic matrix with characteristic nanopatterns was also discovered in the diatom Coscinodiscus wailesii, which suggests that preassembled protein-based templates might be general components of the cellular machinery for silica morphogenesis in diatoms. These data provide fundamentally new insight into the molecular mechanisms of biological silica morphogenesis, and may lead to the development of self-assembled 3D mineral forming protein scaffolds with designed nanopatterns for a host of applications in nanotechnology. PMID:21300899

  14. Cenozoic Planktonic Marine Diatom Diversity and Correlation to Climate Change

    PubMed Central

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Trke, Andreas

    2014-01-01

    Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ?18O (climate) and carbon cycle records (?13C, and 20-0 Ma pCO2). Warmer climates are strongly correlated with lower diatom diversity (raw: rho?=?.92, p<.001; detrended, r?=?.6, p?=?.01). Diatoms were 20% less diverse in the early late Miocene, when temperatures and pCO2 were only moderately higher than today. Diversity is strongly correlated to both ?13C and pCO2 over the last 15 my (for both: r>.9, detrended r>.6, all p<.001), but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls. PMID:24465441

  15. Damping mechanisms in fiber reinforced laminates

    NASA Technical Reports Server (NTRS)

    Plunkett, R.

    1983-01-01

    Low strain damping in fiber reinforced composite materials is due to material loss factors in both fibers and matrix materials. The high modulus of the fibers makes up for the low damping factor. Strains high enough to cause transverse layer cracking in laminates with organic matrix materials causes a large permanent increase in the damping factor. This increase is not due to the transverse cracks but rather to short microcracks in the high shear strain regions. Other damping mechanisms at high strains are also discussed.

  16. Micromechanics of composite laminate compression failures

    NASA Technical Reports Server (NTRS)

    Guynn, E. Gail; Bradley, Walter L.

    1988-01-01

    The purpose of this annual progress report is to summarize the work effort and results accomplished from July 1987 through July 1988 on NASA Research Grant NAG1-659 entitled Micromechanics of Composite Laminate Compressive Failure. The report contains: (1) the objective of the proposed research, (2) the summary of accomplishments, (3) a more extensive review of compression literature, (4) the planned material (and corresponding properties) received to date, (5) the results for three possible specimen geometries, experimental procedures planned, and current status of the experiments, and (6) the work planned for the next contract year.

  17. Laminated anisotropic reinforced plastic plates and shells

    NASA Technical Reports Server (NTRS)

    Korolev, V. I.

    1981-01-01

    Basic technical theories and engineering calculation equations for anisotropic plates and shells made of rigid reinforced plastics, mainly laminated fiberglass, are presented and discussed. Solutions are given for many problems of design of structural plates and shells, including curved sections and tanks, as well as two chapters on selection of the optimum materials, are given. Accounting for interlayer shearing and transverse separation, which are new engineering properties, are discussed. Application of the results obtained to thin three ply plates and shells wth a light elastic filler is presented and discussed.

  18. An Algorithm For Computation Of Diatomic Spectra

    NASA Astrophysics Data System (ADS)

    Hornkohl, J. O.; Woods, A. C.; Parigger, C. G.

    2014-11-01

    In principle, an atomic or molecular spectrum would be computed as follows: Upper and lower Hamiltonians would be enumerated in a complete basis, and numerically diagonalized to give the upper and lower energy eigenvalues and eigenvectors. The transition moments for the appropriate operator, e.g., the electric dipole transition moments, would be evaluated from the eigenvectors. The vacuum wavenumbers , i.e., energy eigenvalue differences, would be found for all non-vanishing transition moments. And the line strengths for each spectral line of wavenumber would be determined as sum of the squares of the transition moments over all transitions producing the same . A line list that includes line strengths would be generated by repeating the above computations over the required range of upper and lower total angular momentum quantum numbers. The spectrum from min to max would be separated into a number of pixels, subsequently, the contribution of each line to each pixel is calculated using the line list. We show how this algorithm can be implemented for a diatomic spectrum if the required molecular parameters are available.

  19. SCALED MODELS FOR LAMINATED CYLINDRICAL SHELLS SUBJECTED TO EXTERNAL PRESSURE

    Microsoft Academic Search

    G. J. Simitses; J. Rezaeepazhand; R. L. Sierakowski

    1997-01-01

    This study investigates problems associated with the design of scaled-down models for laminated cylindrical shells. For better understanding the applicability of scaled-down models in designing laminated composite structures, an analytical investigation was undertaken to assess the feasibility of their use. Such study is important because it provides the necessary scaling laws, and the factors that affect the accuracy of the

  20. A theory for predicting composite laminate warpage resulting from fabrication

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1974-01-01

    Linear laminate theory is used with the moment-curvature relationship to derive equations for predicting end deflections due to warpage without solving the coupled fourth-order partial differential equations of the plate. Composite micro- and macrohyphenmechanics are used with laminate theory to assess the contribution of factors such as ply misorientation, fiber migration, and fiber and/or void volume ratio nonuniformity on the laminate warpage. Using these equations, it was found that a 1 deg error in the orientation angle of one ply was sufficient to produce warpage end deflection equal to two laminate thicknesses in a 10 inch by 10 inch laminate made from 8 ply Mod-I/epoxy. Using a sensitivity analysis on the governing parameters, it was found that a 3 deg fiber migration or a void volume ratio of three percent in some plies is sufficient to produce laminate warpage corner deflection equal to several laminate thicknesses. Tabular and graphical data are presented which can be used to identify possible errors contributing to laminate warpage and/or to obtain an a priori assessment when unavoidable errors during fabrication are anticipated.

  1. Laminated sheet composites reinforced with modular filament sheet

    NASA Technical Reports Server (NTRS)

    Reece, O. Y.

    1968-01-01

    Aluminum and magnesium composite sheet laminates reinforced with low density, high strength modular filament sheets are produced by diffusion bonding and explosive bonding. Both processes are accomplished in normal atmosphere and require no special tooling or cleaning other than wire brushing the metal surfaces just prior to laminating.

  2. Micro-crack ultrasound scattering in anisotropic composite laminates

    NASA Astrophysics Data System (ADS)

    Roberts, R. A.

    2013-01-01

    A computational model of ultrasound scattering by micro-cracks in fiber reinforced polymer laminates is presented, foundational to study of micro-crack induced ultrasound attenuation. A model for transmission scattering response is developed using a boundary integral formulation, and associated approximate scattering theories are discussed. Numerical results are presented demonstrating application of the model to laminates containing distributed micro-cracking.

  3. Self-heating forecasting for thick laminate specimens in fatigue

    NASA Astrophysics Data System (ADS)

    Lahuerta, F.; Westphal, T.; Nijssen, R. P. L.

    2014-12-01

    Thick laminate sections can be found from the tip to the root in most common wind turbine blade designs. Obtaining accurate and reliable design data for thick laminates is subject of investigations, which include experiments on thick laminate coupons. Due to the poor thermal conductivity properties of composites and the material self-heating that occurs during the fatigue loading, high temperature gradients may appear through the laminate thickness. In the case of thick laminates in high load regimes, the core temperature might influence the mechanical properties, leading to premature failures. In the present work a method to forecast the self-heating of thick laminates in fatigue loading is presented. The mechanical loading is related with the laminate self-heating, via the cyclic strain energy and the energy loss ratio. Based on this internal volumetric heat load a thermal model is built and solved to obtain the temperature distribution in the transient state. Based on experimental measurements of the energy loss factor for 10mm thick coupons, the method is described and the resulting predictions are compared with experimental surface temperature measurements on 10 and 30mm UD thick laminate specimens.

  4. On the Bearing Strength of Bolted Graphite\\/Epoxy Laminates

    Microsoft Academic Search

    Ingvar Eriksson

    1990-01-01

    One of the basic failure modes of bolted composite laminates is bearing fail ure. This mode of failure occurs in the material immediately adjacent to the contact points of bolt and laminate, and is caused primarily by compressive stresses acting on the hole boundary. The results of an experimental program which measured the bearing strengths of two different types of

  5. Prediction of progressive failure in multidirectional composite laminated panels

    Microsoft Academic Search

    Shiladitya Basu; Anthony M. Waas; Damodar R. Ambur

    2007-01-01

    A mechanism-based progressive failure analyses (PFA) approach is developed for fiber reinforced composite laminates. Each ply of the laminate is modeled as a nonlinear elastic degrading lamina in a state of plane stress according to Schapery theory (ST). In this theory, each lamina degrades as characterized through laboratory scale experiments. In the fiber direction, elastic behavior prevails, however, in the

  6. A LOCKING-FREE LAMINATED COMPOSITE PLATE FINITE ELEMENT

    Microsoft Academic Search

    Ivan Moura Belo

    2005-01-01

    A plate finite element which is locking-free is developed usi ng strain gradient notation for the analysis of laminated composites. The element is based on a first-order s hear deformation theory and on the equivalent lamina assumption. Strains and stresses can be calculated at diffe rent points through the laminate's thickness. The paraboli c nature of the transverse shear strain

  7. Edge element computations of eddy currents in laminated materials

    Microsoft Academic Search

    Yueqiang Liu; A. Bondeson; R. Bergstrom; M. G. Larson; K. Samuelsson

    2003-01-01

    We studied different types of edge elements in three-dimensional computations of power dissipation in laminated conductors. The standard, lowest order (mixed first and zeroth order) basis on tetrahedral grids produces inaccurate results and grossly overestimates the losses. However, on hexahedral grids, aligned with the laminations, the standard edge elements give much more accurate results. If the grid cannot be aligned

  8. Semitransparent Organic Photovoltaic Cells with Laminated Top Electrode

    E-print Network

    Cui, Yi

    Semitransparent Organic Photovoltaic Cells with Laminated Top Electrode Jung-Yong Lee, Steve T demonstrate semitransparent small molecular weight organic photovoltaic cells using a laminated silver electrodes, nanowires O rganic photovoltaic cells are considered a promis- ing solar cell technology because

  9. High frequency electromagnetic emissions of cylindrical laminated cores

    Microsoft Academic Search

    Stphane Duchesne; J-Ph. Lecointe; F. Prisse; Ewa Napieralska-Juszczak

    2008-01-01

    Purpose This paper aims to propose a high-frequency (HF) model able to compute the flux density in the vicinity of the laminated stator core of an AC machine. Design\\/methodology\\/approach Experiments form the main approach. Analytical results previously obtained with a simplified rectangular laminated structure are confirmed with a standard cylindrical magnetic core. Findings Three frequency domains are

  10. Curvature shape based impact damage detection in composite laminates

    NASA Astrophysics Data System (ADS)

    Feng, Kan; Li, Zheng; Gong, Xiaojing

    2014-02-01

    In this study a vibration-based damage detection method-2D GSM (Two-Dimensional Gapped Smoothing Method), for plate-like structure is presented. A kind of typical carbon fibre reinforced composite laminate is studied as a quasi-isotropic and quasi-homogeneous material. The impact damage was produced by a drop weight acting on the surface of unidirectional tensile stressed composite laminate. For the delamination detaction of laminate by 2D GSM, PZT patches were arranged as actuators to excite the torsion mode of laminate under a certain frequency. By changing the frequency and the phase of signal inputted into each patch, we can actuate the laminate into different operational deflection shapes (ODSs). The deflection shapes of laminate are measured by a Scanning Laser Doppler Vibrometer (SLDV) system. A curvature shape based Two Dimensional Gapped Smoothing Method (2D GSM) is proposed and applied to locate the delamination of laminate caused by impact. The result shows that the 2D GSM is an efficient way for the damage detection in composite laminates.

  11. Tracer lamination in the stratosphere: A global climatology

    Microsoft Academic Search

    Christof Appenzeller; James R. Holton

    1997-01-01

    Vertical soundings of stratospheric ozone often exhibit laminated tracer structures characterized by strong vertical tracer gradients. The change in time of these gradients is used to define a tracer lamination rate. It is shown that this quantity can be calculated by the cross product of the horizontal temperature and horizontal tracer gradients. A climatology based on UARS satellite-borne ozone data

  12. Matrix cracking in laminated composites under monotonic and cyclic loadings

    NASA Technical Reports Server (NTRS)

    Allen, David H.; Lee, Jong-Won

    1991-01-01

    An analytical model based on the internal state variable (ISV) concept and the strain energy method is proposed for characterizing the monotonic and cyclic response of laminated composites containing matrix cracks. A modified constitution is formulated for angle-ply laminates under general in-plane mechanical loading and constant temperature change. A monotonic matrix cracking criterion is developed for predicting the crack density in cross-ply laminates as a function of the applied laminate axial stress. An initial formulation for a cyclic matrix cracking criterion for cross-ply laminates is also discussed. For the monotonic loading case, a number of experimental data and well-known models are compared with the present study for validating the practical applicability of the ISV approach.

  13. IDENTIFICATION AND COMPARATIVE GENOMIC ANALYSIS OF SIGNALING AND REGULATORY COMPONENTS IN THE DIATOM THALASSIOSIRA PSEUDONANA1

    E-print Network

    Berges, John A.

    IN THE DIATOM THALASSIOSIRA PSEUDONANA1 Anton Montsant Laboratory of Molecular Plant Biology, CNRS UMR 8186 the globe. The first whole-genome sequence from a diatom species, Thalassiosira pseu- donana Hasle et

  14. A simple digestion method with a lefort aqua regia solution for diatom extraction.

    PubMed

    Wang, Huipin; Liu, Yan; Zhao, Jian; Hu, Sunlin; Wang, Yuzhong; Liu, Chao; Zhang, Yanji

    2015-01-01

    Presence of diatoms in tissues has been considered as a significant sign of drowning. However, there are limitations in the present extraction methods. We developed a new digestion method using the Lefort aqua regia solution (3:1 nitric acid to hydrochloric acid) for diatom extraction and evaluated the digestive capability, diatom destruction, and diatoms' recovery of this new method. The kidney tissues from rabbit mixed with water rich in diatoms were treated by the Lefort aqua regia digestion method (n=10) and the conventional acid digestion method (n=10). The results showed that the digestive capability of Lefort aqua regia digestion method was superior to conventional acid digestion method (p<0.01); the structure of diatom remained almost intact; and the recovery of diatom was comparable to the conventional acid digestion method (p>0.05). The Lefort aqua regia reagent is an improvement over the conventional acid digestion for recovery of diatoms from tissue samples. PMID:25399968

  15. Influence of cobalamin scarcity on diatom molecular physiology and identification of a cobalamin acquisition protein

    E-print Network

    Bertrand, Erin Marie

    Diatoms are responsible for ?40% of marine primary production and are key players in global carbon cycling. There is mounting evidence that diatom growth is influenced by cobalamin (vitamin B12) availability. This ...

  16. Factors Affecting Carbohydrate Production and the Formation of Transparent Exopolymer Particles (TEP) by Diatoms

    E-print Network

    Chen, Jie

    2014-03-25

    , the efficiency of the biological carbon pump. The objective of this research was to determine how different factors affect carbohydrate production and the formation of TEP by diatoms, and their role in aggregation. Diatoms were grown in laboratory cultures...

  17. Free Vibration of Uncertain Unsymmetrically Laminated Beams

    NASA Technical Reports Server (NTRS)

    Kapania, Rakesh K.; Goyal, Vijay K.

    2001-01-01

    Monte Carlo Simulation and Stochastic FEA are used to predict randomness in the free vibration response of thin unsymmetrically laminated beams. For the present study, it is assumed that randomness in the response is only caused by uncertainties in the ply orientations. The ply orientations may become random or uncertain during the manufacturing process. A new 16-dof beam element, based on the first-order shear deformation beam theory, is used to study the stochastic nature of the natural frequencies. Using variational principles, the element stiffness matrix and mass matrix are obtained through analytical integration. Using a random sequence a large data set is generated, containing possible random ply-orientations. This data is assumed to be symmetric. The stochastic-based finite element model for free vibrations predicts the relation between the randomness in fundamental natural frequencies and the randomness in ply-orientation. The sensitivity derivatives are calculated numerically through an exact formulation. The squared fundamental natural frequencies are expressed in terms of deterministic and probabilistic quantities, allowing to determine how sensitive they are to variations in ply angles. The predicted mean-valued fundamental natural frequency squared and the variance of the present model are in good agreement with Monte Carlo Simulation. Results, also, show that variations between plus or minus 5 degrees in ply-angles can affect free vibration response of unsymmetrically and symmetrically laminated beams.

  18. Development of a heterogeneous laminating resin system

    NASA Technical Reports Server (NTRS)

    Biermann, T. F.; Hopper, L. C.

    1985-01-01

    The factors which effect the impact resistance of laminating resin systems and yet retain equivalent performance with the conventional 450 K curing epoxy matrix systems in other areas were studied. Formulation work was conducted on two systems, an all-epoxy and an epoxy/bismaleimide, to gain fundamental information on the effect formulation changes have upon neat resin and composite properties. The all-epoxy work involved formulations with various amounts and combinations of eight different epoxy resins, four different hardeners, fifteen different toughening agents, a filler, and a catalyst. The epoxy/bismaleimide effort improved formulations with various amounts and combinations of nine different resins, four different hardeners, eight different toughening agents, four different catalysts, and a filler. When a formulation appeared to offer the proper combination of properties required for a laminating resin Celion 3K-70P fabric was prepregged. Initial screening tests on composites primarily involved Gardner type impact and measurement of short beam shear strengths under dry and hot/wet conditions.

  19. Lamins as mediators of oxidative stress

    SciTech Connect

    Sieprath, Tom; Darwiche, Rabih [Cell Systems and Cellular Imaging Group, Department of Molecular Biotechnology, Ghent University, Ghent (Belgium)] [Cell Systems and Cellular Imaging Group, Department of Molecular Biotechnology, Ghent University, Ghent (Belgium); De Vos, Winnok H., E-mail: Winnok.DeVos@UGent.be [Cell Systems and Cellular Imaging Group, Department of Molecular Biotechnology, Ghent University, Ghent (Belgium); NB-Photonics, Ghent University, Ghent (Belgium)

    2012-05-18

    Highlights: Black-Right-Pointing-Pointer The nuclear lamina defines structural and functional properties of the cell nucleus. Black-Right-Pointing-Pointer Lamina dysfunction leads to a broad spectrum of laminopathies. Black-Right-Pointing-Pointer Recent data is reviewed connecting laminopathies to oxidative stress. Black-Right-Pointing-Pointer A framework is proposed to explain interactions between lamins and oxidative stress. -- Abstract: The nuclear lamina defines both structural and functional properties of the eukaryotic cell nucleus. Mutations in the LMNA gene, encoding A-type lamins, lead to a broad spectrum of diseases termed laminopathies. While different hypotheses have been postulated to explain disease development, there is still no unified view on the mechanistic basis of laminopathies. Recent observations indicate that laminopathies are often accompanied by altered levels of reactive oxygen species and a higher susceptibility to oxidative stress at the cellular level. In this review, we highlight the role of reactive oxygen species for cell function and disease development in the context of laminopathies and present a framework of non-exclusive mechanisms to explain the reciprocal interactions between a dysfunctional lamina and altered redox homeostasis.

  20. The clinicopathological significance of lamin A/C, lamin B1 and lamin B receptor mRNA expression in human breast cancer.

    PubMed

    Wazir, Umar; Ahmed, Mai Hassan; Bridger, Joanna M; Harvey, Amanda; Jiang, Wen G; Sharma, Anup K; Mokbel, Kefah

    2013-12-01

    Lamin A/C (LMNA), lamin B1 (LMNB1) and lamin B receptor (LBR) have key roles in nuclear structural integrity and chromosomal stability. In this study, we have studied the relationships between the mRNA expressions of A-type lamins, LMNB1 and LBR and the clinicopathological parameters in human breast cancer. Samples of breast cancer tissues (n = 115) and associated non-cancerous tissue (ANCT; n = 30) were assessed using reverse transcription and quantitative PCR. Transcript levels were correlated with clinicopathological data. Higher levels of A-type lamins and LMNB1 mRNA expression were seen in ANCT. Higher lamin A/C expression was associated with the early clinical stage (TNM1 vs. TNM3 - 13 vs. 0.21; p = 0.0515), with better clinical outcomes (disease-free survival vs. mortality - 11 vs. 1; p = 0.0326), and with better overall (p = 0.004) and disease-free survival (p = 0.062). The expression of LMNB1 declined with worsening clinical outcome (disease-free vs. mortalities - 0.0011 vs. 0.000; p = 0.0177). LBR mRNA expression was directly associated with tumor grade (grade 1 vs. grade 3 - 0.00 vs. 0.00; p = 0.0479) and Nottingham Prognostic Index (NPI1 vs. NPI3 - 0.00 vs. 0.00; p = 0.0551). To the best of our knowledge, this is the first study to suggest such a role for A-type lamins, lamin B1 and LBR in human breast cancer, identifying an important area for further research. PMID:24293108

  1. Bound-free Spectra for Diatomic Molecules

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.

    2012-01-01

    It is now recognized that prediction of radiative heating of entering space craft requires explicit treatment of the radiation field from the infrared (IR) to the vacuum ultra violet (VUV). While at low temperatures and longer wavelengths, molecular radiation is well described by bound-bound transitions, in the short wavelength, high temperature regime, bound-free transitions can play an important role. In this work we describe first principles calculations we have carried out for bound-bound and bound-free transitions in N2, O2, C2, CO, CN, NO, and N2+. Compared to bound ]bound transitions, bound-free transitions have several particularities that make them different to deal with. These include more complicated line shapes and a dependence of emission intensity on both bound state diatomic and atomic concentrations. These will be discussed in detail below. The general procedure we used was the same for all species. The first step is to generate potential energy curves, transition moments, and coupling matrix elements by carrying out ab initio electronic structure calculations. These calculations are expensive, and thus approximations need to be made in order to make the calculations tractable. The only practical method we have to carry out these calculations is the internally contracted multi-reference configuration interaction (icMRCI) method as implemented in the program suite Molpro. This is a widely used method for these kinds of calculations, and is capable of generating very accurate results. With this method, we must first of choose which electrons to correlate, the one-electron basis to use, and then how to generate the molecular orbitals.

  2. The coupled states approximation for scattering of two diatoms

    NASA Technical Reports Server (NTRS)

    Heil, T. G.; Kouri, D. J.; Green, S.

    1978-01-01

    The paper presents a detailed development of the coupled-states approximation for the general case of two colliding diatomic molecules. The high-energy limit of the exact Lippman-Schwinger equation is applied, and the analysis follows the Shimoni and Kouri (1977) treatment of atom-diatom collisions where the coupled rotor angular momentum and projection replace the single diatom angular momentum and projection. Parallels to the expression for the differential scattering amplitude, the opacity function, and the nondiagonality of the T matrix are reported. Symmetrized expressions and symmetrized coupled equations are derived. The present correctly labeled coupled-states theory is tested by comparing its calculated results with other computed results for three cases: H2-H2 collisions, ortho-para H2-H2 scattering, and H2-HCl.

  3. Ultrastructural observations on the marine fouling diatom Amphora

    NASA Astrophysics Data System (ADS)

    Daniel, G. F.; Chamberlain, A. H. L.; Jones, E. B. G.

    1980-06-01

    Ecological and Scanning electron microscope (S. E. M.) studies indicated that the diatom Amphora was an important constituent in the initial colonization of test panels coated with a copper antifouling composition. Amphora was also found as the dominant fouling diatom species on paint samples from in-service supertankers and yachts. Associated with the diatom was copious amounts of mucilaginous material, which often encapsulated the cells. Histochemical analysis of the mucilage indicates that it is predominantly polysaccharide in nature. Using the Transmission electron microscope (T. E. M.) and electron microscope cytochemistry the intracellular origin of the adhesive was investigated. T. E. M. and S. E. M. observations of acid-cleaned-cells indicate that the mucilage may be secreted through specialized regions of the frustule. Material isolated from antifouling panels was compared with laboratory cultured Amphora spp. for copper resistance and internal accumulation using TEMSCAN X ray analytical equipment.

  4. Circular random motion in diatom gliding under isotropic conditions

    NASA Astrophysics Data System (ADS)

    Gutirrez-Medina, Braulio; Jimnez Guerra, Andrs; Pea Maldonado, Ana Iris; Covarrubias Rubio, Yadiralia; Viridiana Garca Meza, Jessica

    2014-12-01

    How cells migrate has been investigated primarily for the case of trajectories composed by joined straight segments. In contrast, little is known when cellular motion follows intrinsically curved paths. Here, we use time-lapse optical microscopy and automated trajectory tracking to investigate how individual cells of the diatom Nitzschia communis glide across surfaces under isotropic environmental conditions. We find a distinct kind of random motion, where trajectories are formed by circular arcs traveled at constant speed, alternated with random stoppages, direction reversals and changes in the orientation of the arcs. Analysis of experimental and computer-simulated trajectories show that the circular random motion of diatom gliding is not optimized for long-distance travel but rather for recurrent coverage of limited surface area. These results suggest that one main biological role for this type of diatom motility is to efficiently build the foundation of algal biofilms.

  5. Understanding amine catalyzed silica polymerization : diatoms as bioarchitects.

    SciTech Connect

    Spoerke, Erik David; Aubry, Sylvie; Lane, Pamela; Robinson, David B; Bauer, Christina A.; Zendejas, Frank; Tran, Huu; Lane, Todd W.; Simmons, Blake Alexander

    2007-10-01

    Current state-of-the-art biomimetic methodologies employed worldwide for the realization of self-assembled nanomaterials are adequate for certain unique applications, but a major breakthrough is needed if these nanomaterials are to obtain their true promise and potential. These routes typically utilize a 'top-down' approach in terms of controlling the nucleation, growth, and deposition of structured nanomaterials. Most of these techniques are inherently limited to primarily 2D and simple 3D structures, and are therefore limited in their ultimate functionality and field of use. Zeolites, one of the best-known and understood synthetic silica structures, typically possess highly ordered silica domains over very small length scales. The development of truly organized and hierarchical zeolites over several length scales remains an intense area of research world wide. Zeolites typically require high-temperature and complex synthesis routes that negatively impact certain economic parameters and, therefore, the ultimate utility of these materials. Nonetheless, zeolite usage is in the tons per year worldwide and is quickly becoming ubiquitous in its applications. In addition to these more mature aspects of current practices in materials science, one of the most promising fields of nanotechnology lies in the advent and control of biologically self-assembled materials, especially those involved with silica and other ceramics such as hydroxyapatite. Nature has derived, through billions of years of evolutionary steps, numerous methods by which fault-tolerant and mechanically robust structures can be created with exquisite control and precision at relatively low temperature ranges and pressures. Diatoms are one of the best known examples that exhibit this degree of structure and control known that is involved with the biomineralization of silica. Diatoms are eukaryotic algae that are ubiquitous in marine and freshwater environments. They are a dominant form of phytoplankton critical to global carbon fixation. The silicified cell wall of the diatom is called the frustule, and the intricate silica structure characteristic of a given species is known as the valve. There are two general classes of diatoms, based on their overall morphologies, the pennate and centric. Diatoms achieve their silicified structures in exact fashion through genetically inspired design rules coupled with precisely directed biochemistry occurring at temperatures ranging from a few degrees Celsius (polar species) to temperatures just over room temperature (tropical species). Different species of diatoms produce markedly different structures. To start with, there are two basic types of frustule macromorphologies: pennate diatoms display bilateral symmetry and centric diatoms show radial symmetry. There are thousands of permutations of these two basic forms and the micromorphology of the valve can be quite complex with all types of pore arrangements and morphologies (Figure 1.1). The detailed morphology of the cell wall of a given diatom species is reproduced with exactness, because the process is genetically encoded. Three types of cell wall proteins have been identified in diatoms; the frustulins, pleuralins, and silaffins. Frustulins are cell wall proteins that form an organic coat to protect the silica structures from dissolution into the aqueous environment. Pleuralins are associated with a specific subcomponent of the frustule during cell division, and play a role in hypotheca-epitheca development. Silaffins from Cylindrotheca fusiformis are short chain-length peptides that play a direct role in the silica polymerization process, and possess unique biochemical post-translation functionalization. Larger proteins with silaffin activity have recently been described in Thalassiosira pseudonana. Frustulins and pleuralins play no role in silica polymerization or structure formation in diatoms, whereas the silaffins are one of the primary polymerization determinants. In addition to the silaffins, a class of long-chain polyamines associated with diatom silica has been

  6. Long-term decomposition of DOC from experimental diatom blooms

    SciTech Connect

    Fry, B.; Hopkinson, C.S. Jr.; Nolin, A. [Ecosystems Center, Woods Hole, MA (United States)

    1996-09-01

    Decomposition of {sup 13}C-labeled dissolved organic carbon (DOC) produced in two marine diatom blooms was followed for 2.5 yr with large volume (20 liter) incubations performed in the dark. The {sup 13}C tracer was used to partition decomposition dynamics of the fresh diatom-derived DOC and the turnover of background DOC from Woods Hole Harbor. DOC from Woods Hole harbor proved largely refractory, with DOC concentrations falling from 122 to {approximately} 100 {mu}M C in 2.5 yr. DOC from the diatom blooms was more labile, but was also incompletely mineralized, with 25-35% remaining after 2.5 yr. Neither nutrients nor labile carbon (dextrose) added at 1.5 yr significantly stimulated DOC mineralization. The experiments indicate that DOC produced in short-term blooms can be surprisingly resistant to microbial attack. 21 refs., 1 fig., 1 tab.

  7. A Guide to the Common Diatoms at Water Pollution Surveillance System Stations.

    ERIC Educational Resources Information Center

    Weber, Cornelius I.

    This guide was developed by the United States Environmental Protection Agency (EPA) as a taxonomic reference for the identification of diatoms. The taxonomic information included consists of a generic key to the common genera of diatoms, a section illustrating 164 diatom species representing 43 common genera found at the Water Pollution

  8. Accumulation of 241Am by suspended matter, diatoms and aquatic weeds of the Yenisei River

    Microsoft Academic Search

    T. A. Zotina; A. Ya. Bolsunovsky; L. G. Bondareva

    2010-01-01

    In this work we experimentally estimated the capacities of the key components of the Yenisei River (Russia): particulate suspended matter (seston), diatom microalgae, and submerged macrophytes for accumulating 241Am from water. In our experiments large particles of seston (>8?m), comparable in size with diatoms, took up most of americium from water. The accumulation of americium by isolated diatom algae (Asterionella

  9. USING DIATOMS AS INDICATORS OF ECOLOGICAL CONDITIONS IN LOTIC SYSTEMS: A REGIONAL ASSESSMENT

    EPA Science Inventory

    Benthic diatoms and water chemistry were sampled from 49 stream sites in the Mid-Atlantic Highlands region of the United States to evaluate the use of diatoms as indicators of environmental conditions in streams across varying geographic and ecoregional areas. Diatom samples were...

  10. Silica Use Through Time: Macroevolutionary Change in the Morphology of the Diatom Fustule

    Microsoft Academic Search

    Zoe V. Finkel; Benjamin Kotrc

    2010-01-01

    Diatoms have evolved an obligate requirement for silica for their ornamented cell wall. Diatom productivity and subsequent burial of their siliceous remains on the ocean floor is a major control on the marine silica cycle. The ecological success of the diatoms over the Mesozoic and Cenozoic is associated with biogeographic shifts in siliceous sponges, decreasing silicification in the radiolarians, and

  11. Effects of light fluctuations on the growth and productivity of Antarctic diatoms in culture

    Microsoft Academic Search

    Anne Mortain-Bertrand; M. Curie

    1989-01-01

    This work shows that the low division rates observed in diatoms in Antarctic waters seem to be due to conditions of irradiance rather than to the low temperature: low light intensity and light fluctuations are two factors which depress the division rate of diatoms. However, with regard to the productivity, Antarctic diatoms seem well-adapted to their turbulent environment. Cells grown

  12. The amino acid and sugar composition of diatom cell-walls

    Microsoft Academic Search

    R. E. Hecky; K. Mopper; P. Kilham; E. T. Degens

    1973-01-01

    The cell walls of diatoms consist of a silica frustule encased in an organic coating. Biochemical characterization of this coating should allow insight into: (1) the mechanism of silicification; (2) taxonomy and evolution of diatoms; (3) preservation of fossil frustules. The amino acid and sugar composition of cell walls from 6 diatom species have been elucidated. When compared to cellular

  13. Diatom metrics for monitoring eutrophication in rivers of the United States

    Microsoft Academic Search

    Marina Potapova; Donald F. Charles

    2007-01-01

    Two major arguments in favor of using diatoms in water-quality assessments are that their distributions are cosmopolitan and their ecology is well studied. If these assumptions are true, diatom-based monitoring tools could be considered universal and used in any geographic area. Indeed, some diatom metrics based on species indicator values developed in Europe are often used in North America and

  14. Freshwater diatoms as environmental indicators: evaluating the effects of eutrophication using species morphology and biological indices.

    PubMed

    Vilmi, Annika; Karjalainen, Satu Maaria; Landeiro, Victor L; Heino, Jani

    2015-05-01

    Anthropogenic eutrophication is a major form of perturbation in freshwaters, and several approaches aim to recognise its effects on lake ecosystems. We compared the responses of diatom species morphology, diversity indices and diatom indices to total phosphorus, total nitrogen and distance from a point stressor causing eutrophication in a large lake. We specifically examined the degree to which extent nutrients and distance to the stressor affect variation in the values of various biological indices and diatom valve size. In addition, special attention was given to the adequate repetition of diatom valve width measurements in the context of environmental assessment. Our results showed that diatom valve width was a better indicator of nutrient concentrations than any of the diatom and diversity indices examined. However, the results varied between the two study transects, suggesting that the diatom-based variables not only respond to nutrients but also to other environmental factors (e.g. shoreline morphology). We also found that when using the method based on diatom morphology, one should measure more valves than has been originally suggested to provide a more reliable picture of response to eutrophication. We argue that diatom morphology could be considered as an additional environmental assessment tool, because it may complement the information provided by the traditional diatom indices. Diatom valve width may also be more sensitive to early phases of the eutrophication process and its effects on freshwater ecosystems than various diatom indices that were developed in regional contexts with wide ranges in nutrient levels. PMID:25864081

  15. Diatom diet selectivity by early post-larval abalone Haliotis diversicolor supertexta under hatchery conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Yuyu; Gao, Yahui; Liang, Junrong; Chen, Changping; Zhao, Donghai; Li, Xuesong; Li, Yang; Wu, Wenzhong

    2010-11-01

    Benthic diatoms constitute the primary diet of abalone during their early stages of development. To evaluate the dietary preferences of early post-larval abalone, Haliotis diversicolor supertexta, we analyzed the gut contents of post-larvae that settled on diatom films. We compared the abundance and species diversity of diatom assemblages in the gut to those of the epiphytic diatom assemblages on the attachment films, and identified 40 benthic diatom species in the gut contents of post-larvae 12 to 24 d after settlement. The most abundant taxa in the gut contents were Navicula spp., Amphora copulate, and Amphora coffeaeformis. Navicula spp. accounted for 64.0% of the cell density. In the attachment films, we identified 110 diatom species belonging to 38 genera. Pennate diatoms were the dominant members including the species Amphiprora alata, Cocconeis placentula var. euglypta, Cylindrotheca closterium, Navicula sp. 2, and A. coffeaeformis. Nano-diatoms (<20 ?m in length) accounted for a considerable proportion of the total species number and cell density of the diatom assemblages in the gut contents and on the films. This suggests that nano-diatoms are important to the efficient production of abalone seed. The difference of the composition and abundance of diatoms between in the guts and on the biofilms suggests that early post-larval grazing was selective. An early post-larval abalone preferred nano-diatoms and the genera Navicula and Amphora during the month after settlement.

  16. Role of diatoms in nickel biogeochemistry in the ocean

    NASA Astrophysics Data System (ADS)

    Twining, Benjamin S.; Baines, Stephen B.; Vogt, Stefan; Nelson, David M.

    2012-12-01

    Dissolved nickel (Ni) typically displays a `nutrient-like' vertical profile in the ocean, with lower concentrations in surface waters and higher concentrations in deep waters, similar to other micronutrient metals such as iron and zinc. Vertical profiles of Ni show particular similarities to profiles of the macronutrients phosphate and silicic acid, suggesting that diatoms play an important role in mediating the vertical distribution of this metal. We performed synchrotron x-ray fluorescence (SXRF) analysis on individual phytoplankton cells collected from stations in the equatorial Pacific Ocean and from nutrient-addition incubation experiments conducted on the same cruise. Diatoms were enriched in Ni twofold to fivefold relative to picoplankton and flagellated cells. Changes in cellular quotas of Si, P and Ni observed in diatoms growing in response to Fe and Si additions were used to estimate the Ni:P (0.52 0.10 mmol/mol) and Ni:Si (28 13 ?mol/mol) ratios of internal biomass and the frustule, respectively. Elevated internal Ni:P suggests a heightened role for urease or the Ni isoform of superoxide dismutase in diatoms (similar to cyanobacteria), while Ni associated with the frustule appears to contribute an additional 50% of cellular Ni found in the diatoms. The derived Ni:Si ratio for frustule material is comparable to Ni:Si ratios in published nutrient profiles, confirming the dominant role that diatoms play in ocean Ni biogeochemistry. While a molecular explanation for the association of Ni with frustules remains to be determined, this study demonstrates the unique biogeochemical insight that can be gained from microanalytical element analysis.

  17. Cenozoic planktonic marine diatom diversity and correlation to climate change

    USGS Publications Warehouse

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Trke, Andreas

    2014-01-01

    Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ?18O (climate) and carbon cycle records (?13C, and 20-0 Ma pCO2). Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p2 were only moderately higher than today. Diversity is strongly correlated to both ?13C and pCO2 over the last 15 my (for both: r>.9, detrended r>.6, all p<.001), but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls.

  18. Modeling and detection of quasi-static nanotesla magnetic field variations using magnetoelectric laminate sensors

    Microsoft Academic Search

    Z P Xing; J Y Zhai; S X Dong; J F Li; D Viehland; W G Odendaal

    2008-01-01

    Laminated composites of magnetostrictive and piezoelectric layers have been developed for their magnetoelectric (ME) product tensor properties. In spite of the considerable progress in materials aspects, little attention has been given to ME laminate incorporation into a detection technology. Here, we present a ME technology including the laminate equivalent model, detection circuitry consideration and noise mitigation for ME laminate sensors

  19. Design of laminated composite plates for optimal dynamic characteristics using a constrained global optimization technique

    Microsoft Academic Search

    T. Y. Kam; F. M. Lai

    1995-01-01

    The lamination arrangements of moderately thick laminated composite plates for optimal dynamic characteristics are studied via a constrained multi-start global optimization technique. In the optimization process, the dynamical analysis of laminated composite plates is accomplished by utilizing a shear deformable laminated composite finite element, in which the exact expressions for determining shear correction factors were adopted and the modal damping

  20. Design of laminated composite plates for optimal dynamic characteristics using a constrained global optimization technique

    Microsoft Academic Search

    T. Y. Kam; F. M. Lai

    1995-01-01

    The lamination arrangements of moderately thick laminated composite plates for optimal dynamic characteristics are studied via a constrained multi-start global optimization technique. In the optimization process, the dynamical analysis of laminated composite plates is accomplished by utilizing a shear deformable laminated composite finite element, in which the exact expressions for determining shear correction factors were adopted, and the modal damping

  1. Concentration-dependent lamin assembly and its roles in the localization of other nuclear proteins

    PubMed Central

    Guo, Yuxuan; Kim, Youngjo; Shimi, Takeshi; Goldman, Robert D.; Zheng, Yixian

    2014-01-01

    The nuclear lamina (NL) consists of lamin polymers and proteins that bind to the polymers. Disruption of NL proteins such as lamin and emerin leads to developmental defects and human diseases. However, the expression of multiple lamins, including lamin-A/C, lamin-B1, and lamin-B2, in mammals has made it difficult to study the assembly and function of the NL. Consequently, it has been unclear whether different lamins depend on one another for proper NL assembly and which NL functions are shared by all lamins or are specific to one lamin. Using mouse cells deleted of all or different combinations of lamins, we demonstrate that the assembly of each lamin into the NL depends primarily on the lamin concentration present in the nucleus. When expressed at sufficiently high levels, each lamin alone can assemble into an evenly organized NL, which is in turn sufficient to ensure the even distribution of the nuclear pore complexes. By contrast, only lamin-A can ensure the localization of emerin within the NL. Thus, when investigating the role of the NL in development and disease, it is critical to determine the protein levels of relevant lamins and the intricate shared or specific lamin functions in the tissue of interest. PMID:24523288

  2. Sediment sources and sedimentation processes of 2011 Tohoku-oki tsunami deposits on the Sendai Plain, Japan Insights from diatoms, nannoliths and grain size distribution

    NASA Astrophysics Data System (ADS)

    Szczuci?ski, Witold; Kokoci?ski, Miko?aj; Rzeszewski, Micha?; Chagu-Goff, Catherine; Cacho, Mario; Goto, Kazuhisa; Sugawara, Daisuke

    2012-12-01

    The 11th March 2011 Tohoku-oki tsunami inundated the low-lying Sendai Plain (Japan) more than 5 km inland leaving sand and mud deposits over most of the area. In order to establish the sources of the tsunami deposits and interpret processes of their sedimentation, samples were collected from the deposits, underlying soils and the beach along a shore-perpendicular transect and analysed for grain size, diatom assemblages and nannoliths. The fining-inland tsunami deposits consisted of poorly to moderately sorted medium to coarse sand within 2 km of the coastline and very poorly to poorly sorted mud farther inland. More specifically, there was a slight fining of the coarse to medium sand mode within the sandy deposits and an increased contribution of the coarse and very coarse silt fraction in the mud deposits. The tsunami deposits also exhibited vertical changes including fining upward and coupled coarsening-fining upward trends. Few diatoms were present in beach sediments, soils and tsunami deposits within 1 km of the coastline, while diatoms were more abundant farther inland. Diatom assemblages in the soil and tsunami deposits were similar and dominated by species typical of freshwater-brackish habitats, while no typically marine species were encountered. Nannoliths were generally absent in the studied sediments, except for few specimens. Our data indicate that there was probably no or only a very minor component of marine sediments transported onland by the tsunami. The sandy tsunami deposits within ~ 1 km of the coastline were mostly derived from beach and dune erosion. From 1 to 2 km landward the contribution of these sources decreased, while sources comprising local soil erosion and the entrainment of sediments from the Teizan-bori canal increased. Farther inland, local soil erosion was the major sediment source for the mud deposits. The tsunami deposits were most likely deposited during at least two inundations, mostly out from suspension resulting in an upward grain size fining trend. However, bed load deposition was also important in the sandy deposits as suggested by a common grain size upward coarsening, position on C-M diagrams and frequent horizontal lamination. The present study reveals that even very large tsunamis may not transport marine sediments onland and thus many commonly applied indicators of tsunami deposits based on the assumption of their offshore origin (marine diatoms, foraminifera, nannoliths, marine sediments) may be of limited use.

  3. Interlaminate Deformation in Thermoplastic Composite Laminates: Experimental-Numerical Correlation

    NASA Astrophysics Data System (ADS)

    Shen, M.; Tong, J.; Wang, S.; Fang, Y.

    2010-06-01

    The interlaminar deformation behaviors of thermoplastic AS4/PEEK composite laminates subjected to static tensile loading are investigated by means of microscopic moir interferometry with high spatial resolution. The fully threedimensional orthotropic elastic-plastic analysis of interlaminar deformation for the thermoplastic laminates is developed in this paper, and used to simulate the stress-strain curves of tensile experiment for its angle-ply laminates. Under uniaxial tensile loading, the 3D orthotropic elastic-plastic FE analysis and microscopic moir interferometry of interlaminar deformations are carried out for the [25]S4 laminates. The quantitative local-filed experimental results of interlaminar shear strain and displacements at freeedge surface of the laminate are compared with corresponding numerical results of the orthotropic elastic-plastic FE model. It is indicated that the numerical tensile stressstrain curves of angle-ply laminates computed with 3D orthotropic elastic-plastic model are agree with experimental results. The numerical interlaminar displacement U and shear strain ?xz are also consistent with the experimental results obtained by moir interferometry. It is expected the elastic-plastic interlaminar stresses and deformations analysis for the optimal design and application of AS4/PEEK laminates and its structures.

  4. Effects of monomethylhydrazine on selected species of marine diatoms

    SciTech Connect

    Wendler, B.W.; Norris, D.R.

    1985-07-01

    A safe concentration (SC) and the mean effective concentration (EC) for hydrazine, MMH, and unsymmetrical dimethylhydrazine have been determined on species of green algae. The aqueous degradation of MMH is relatively rapid compared to the time green algae require to reach maximum standing crop. The diatoms Thalassiosira pseudonana and Skeletonema costatum reach maximum standing crop in 6 to 7 days in culture which makes them ideal for testing short-term effects of MMH. The objectives of this study were to determine the relative sensitivity of selected marine diatoms to MMH and whether species composition would be affected by MMH.

  5. Ab initio calculations of the photoionization of diatomic molecules

    NASA Astrophysics Data System (ADS)

    Lefebvre-Brion, Helene; Ra?eev, Georges

    2003-01-01

    A review is presented of the calculation of photoionization spectra, particularly in the spectral range where electron autoionization of diatomic molecules takes place. In addition to some interesting results obtained over years that compare favourably with experiment, the emphasis here is put on the relation between the methods developed for the calculation of observables associated with the continuum energy spectrum of the electrons and the Alchemy system of programs. This system of programs serves as a basis for initial and intermediate calculations. The examples presented show that diatomic molecules not only in gas phase but also oriented in space or physisorbed at surfaces may be studied readily.

  6. Distribution of Epiphytic Diatoms in a Sub-Tropical Estuary

    NASA Astrophysics Data System (ADS)

    Frankovich, T. A.; Gaiser, E. E.; Wachnicka, A.; Zieman, J. C.

    2005-05-01

    Within estuaries, seagrasses may represent an order of magnitude greater surface area relative to sediments for the colonization and growth of diatoms. Fossil diatom distributions have proven useful in inferring paleoenvironmental conditions. The strength of these inferences is dependent upon defining the environmental relationships of contempory diatom compositions. The present investigation characterized the modern epiphytic diatom flora on the seagrass Thalassia testudinum at seven sites in the sub-tropical Florida Bay estuary and at one Atlantic Ocean site east of the upper Florida Keys. These sites were sampled six times between March 2000 and April 2001. Diatom species composition was related to water quality parameters using multivariate statistics. 338 diatom species were identified. The seven most abundant species from pooled samples were Cocconeis placentula, Brachysira aponina, Nitzschia liebetruthii, Hyalosynedra laevigata, Amphora cf. tenerrima, Mastogloia crucicula, and M. pusilla. These seven species collectively accounted for 51.7 percent of all valves counted and occurred in at least 85 percent of all samples. Analysis of similiarity and NMDS ordination of species relative abundances revealed four distinct diatom communities across the study region. The spatial variability of these communities was correlated with salinity and water-column nutrient availability. Summertime communities were significantly different from winter-spring communities, but these communities showed a gradual temporal progression with much overlap. The temporal variability was correlated with temperature. Indicator species analysis identified many species significantly influencing the four spatial groups. The Atlantic marine site was characterized by many different Mastogloia species and some epipsammic (sand-grain associated) diatoms (i.e., Cymatosira lorenziana, Dimerogramma dubium, and Neofragilaria nicobarica). Mastogloia pusilla, Rhopalodia pacifica, and Cocconeis woodii were strong indicators of the Gulf of Mexico marine site. Reimerothrix floridensis was particularly abundant in the western interior of Florida Bay (i.e., sites 2, 3, and 4) during summer months. The eastern interior of Florida Bay was characterized by high relative abundances of Brachysira aponina and Nitzschia liebetruthii. The optima and tolerance of these indicator species relative to individual water quality parameters were also determined.

  7. Interlaminar stresses in composite laminates: A perturbation analysis

    NASA Technical Reports Server (NTRS)

    Hsu, P. W.; Herakovich, C. T.

    1976-01-01

    A general method of solution for an elastic balanced symmetric composite laminate subject to a uniaxial extension was developed based upon a perturbation analysis of a limiting free body containing an interfacial plane. The solution satisfies more physical requirements and boundary conditions than previous investigations, and predicts smooth continuous interlaminar stresses with no instabilities. It determines the finite maximum intensity for the interlaminar normal stress in all laminates, provides mathematical evidences for the singular stresses in angle-ply laminates, suggests the need for the experimental determination of an important problem parameter, and introduces a viable means for solving related problems of practical interest.

  8. Wave propagation in graphite/epoxy laminates due to impact

    NASA Technical Reports Server (NTRS)

    Tan, T. M.; Sun, C. T.

    1982-01-01

    The low velocity impact response of graphite-epoxy laminates is investigated theoretically and experimentally. A nine-node isoparametric finite element in conjunction with an empirical contact law was used for the theoretical investigation. Flat laminates subjected to pendulum impact were used for the experimental investigation. Theoretical results are in good agreement with strain gage experimental data. The collective results of the investigation indicate that the theoretical procedure describes the impact response of the laminate up to about 150 in/sec. impact velocity.

  9. Multi-Layer Laminated Thin Films for Inflatable Structures

    NASA Technical Reports Server (NTRS)

    Yavrouian, Andre; Plett, Gary; Mannella, Jerami

    2005-01-01

    Special-purpose balloons and other inflatable structures would be constructed as flexible laminates of multiple thin polymeric films interspersed with layers of adhesive, according to a proposal. In the original intended application, the laminate would serve as the envelope of the Titan Aerobot a proposed robotic airship for exploring Titan (one of the moons of Saturn). Potential terrestrial applications for such flexible laminates could include blimps and sails. In the original application, the multi-layered laminate would contain six layers of 0.14-mil (0.0036-mm)-thick Mylar (or equivalent) polyethylene terephthalate film with a layer of adhesive between each layer of Mylar . The overall thickness and areal density of this laminate would be nearly the same as those of 1-mil (0.0254-mm)-thick monolayer polyethylene terephthalate sheet. However, the laminate would offer several advantages over the monolayer sheet, especially with respect to interrelated considerations of flexing properties, formation of pinholes, and difficulty or ease of handling, as discussed next. Most of the damage during flexing of the laminate would be localized in the outermost layers, where the radii of bending in a given bend would be the largest and, hence, the bending stress would be the greatest. The adverse effects of formation of pinholes would be nearly completely mitigated in the laminate because a pinhole in a given layer would not propagate to adjacent layers. Hence, the laminate would tend to remain effective as a barrier to retain gas. Similar arguments can be made regarding cracks: While a crack could form as a result of stress or a defect in the film material, a crack would not propagate into adjacent layers, and the adjacent layer(s) would even arrest propagation of the crack. In the case of the monolayer sheet, surface damage (scratches, dents, permanent folds, pinholes, and the like) caused by handling would constitute or give rise to defects that could propagate through the thickness as cracks or pinholes that would render the sheet less effective or ineffective as a barrier. In contrast, because damage incurred during handling of the laminate would ordinarily be limited to the outermost layers, the barrier properties of the laminate would be less likely to be adversely affected. Therefore, handling of the laminate would be easier because there would be less of a need to exercise care to ensure against surface damage.

  10. Prediction of microcracking in composite laminates under thermomechanical loading

    NASA Technical Reports Server (NTRS)

    Maddocks, Jason R.; Mcmanus, Hugh L.

    1995-01-01

    Composite laminates used in space structures are exposed to both thermal and mechanical loads. Cracks in the matrix form, changing the laminate thermoelastic properties. An analytical methodology is developed to predict microcrack density in a general laminate exposed to an arbitrary thermomechanical load history. The analysis uses a shear lag stress solution in conjunction with an energy-based cracking criterion. Experimental investigation was used to verify the analysis. Correlation between analysis and experiment is generally excellent. The analysis does not capture machining-induced cracking, or observed delayed crack initiation in a few ply groups, but these errors do not prevent the model from being a useful preliminary design tool.

  11. Analysis of a hybrid, unidirectional buffer strip laminate

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1983-01-01

    A method of analysis capable of predicting accurately the fracture behavior of a unidirectional composite laminate containing symmetrically placed buffer strips is presented. As an example, for a damaged graphite/epoxy laminate, the results demonstrate the manner in which to select the most efficient combination of buffer strip properties necessary to inhibit crack growth. Ultimate failure of the laminate after crack arrest can occur under increasing load either by continued crack extension through the buffer strips or the crack can jump the buffer strips. For some typical hybrid materials it is found that a buffer strip spacing-to-width ratio of about four to one is the most efficient.

  12. Analysis of a hybrid-undirectional buffer strip laminate

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1983-01-01

    A method of analysis capable of predicting accurately the fracture behavior of a unidirectional composite laminate containing symmetrically placed buffer strips is presented. As an example, for a damaged graphite/epoxy laminate, the results demonstrate the manner in which to select the most efficient combination of buffer strip properties necessary to inhibit crack growth. Ultimate failure of the laminate after the arrest can occur under increasing load either by continued crack extension through the buffer strips or the crack can jump the buffer strips. For some typical hybrid materials it is found that a buffer strip spacing to width ratio of about four to one is the most efficient.

  13. Laminated metals composites fracture and ballistic impact behavior

    SciTech Connect

    Lesuer, D.R.; Syn, C.K.; Sherby, O.D.; Wadsworth, J.

    1998-01-20

    Recent advances in the fracture and ballistic impact response of laminated metal composites (LMCs) are reviewed. The laminate structure can provide significant improvements to these properties relative to the component materials. Typical fracture and ballistic impact properties in LMCs are illustrated for systems containing Al alloys and Al matrix composites. The unique mechanisms operating in a layered structure that contribute to fracture or ballistic impact resistance are discussed. The influence of laminate architecture, component material properties and interface strength on mechanisms and properties are briefly reviewed for these Al-based LMCs.

  14. Accurate stress resultants equations for laminated composite deep thick shells

    SciTech Connect

    Qatu, M.S. [Franklin Univ., Columbus, OH (United States)

    1995-11-01

    This paper derives accurate equations for the normal and shear force as well as bending and twisting moment resultants for laminated composite deep, thick shells. The stress resultant equations for laminated composite thick shells are shown to be different from those of plates. This is due to the fact the stresses over the thickness of the shell have to be integrated on a trapezoidal-like shell element to obtain the stress resultants. Numerical results are obtained and showed that accurate stress resultants are needed for laminated composite deep thick shells, especially if the curvature is not spherical.

  15. Axisymmetric vibrations of laminated composite conical shells with varying thickness

    SciTech Connect

    Shikanai, G.; Suzuki, K. [Yamagata Univ., Yonezawa (Japan). Faculty of Engineering; Kojima, M. [NEC Corporation, Tokyo (Japan)

    1995-11-01

    An exact solution procedure is presented for solving axisymmetric free vibrations of laminated composite conical shells with varying thickness. Based on the classical lamination theory neglecting shear deformation and rotary inertia, equations of motion and boundary conditions are obtained from the stationary conditions of the Lagrangian. The equations of motion are solved exactly by using a power series expansion for symmetrically laminated, cross-ply conical shells. Numerical studies are made for conical shells having both ends clamped to show the effects of the number of laminae, stacking sequences and other parameters upon the frequencies.

  16. Vibration analysis of rotating thin laminated composite shell of revolution

    SciTech Connect

    Suzuki, K.; Shikanai, G.; Takayama, K. [Yamagata Univ., Yonezawa (Japan). Faculty of Engineering

    1995-11-01

    An exact solution procedure is presented for solving free vibrations of a rotating thin laminated composite shell of revolution having meridionally constant curvature. Based on the classical lamination theory, equations of motion and boundary conditions are obtained from the stationally conditions of the Lagrangian. The equations of motion are solved exactly by using a power series expansion for symmetrically laminated, cross-ply shells. Frequencies and mode shapes of the shells having both ends clamped and both ends freely supported are presented showing their variations with rotating angular velocity, number of laminae and other parameters.

  17. The mechanics of fatigue in composite laminates

    NASA Technical Reports Server (NTRS)

    Reifsnider, K. L.

    1982-01-01

    A status report is presented for the development of the mechanics of fatigue in composite materials. A concensus is noted on the need to construct mechanics treatments on the basis of precisely defined damage states which are both characteristic of the material and independent of as many extensive variables, such as load history, as possible. This approach is in keeping with the use of a single crack as the characteristic damage state in homogeneous materials, which has provided a well defined and precise boundary value problem that can be used in the description and prediction of damaged material response. The utility of stress redistribution concepts in determining residual strength, stiffness, and life in composite laminates is also recognized.

  18. Micromechanics of composite laminate compression failure

    NASA Technical Reports Server (NTRS)

    Guynn, E. Gail; Bradley, Walter L.

    1986-01-01

    The Dugdale analysis for metals loaded in tension was adapted to model the failure of notched composite laminates loaded in compression. Compression testing details, MTS alignment verification, and equipment needs were resolved. Thus far, only 2 ductile material systems, HST7 and F155, were selected for study. A Wild M8 Zoom Stereomicroscope and necessary attachments for video taping and 35 mm pictures were purchased. Currently, this compression test system is fully operational. A specimen is loaded in compression, and load vs shear-crippling zone size is monitored and recorded. Data from initial compression tests indicate that the Dugdale model does not accurately predict the load vs damage zone size relationship of notched composite specimens loaded in compression.

  19. Permeability After Impact Testing of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, A.T.; Munafo, Paul (Technical Monitor)

    2002-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

  20. Permeability After Impact Testing of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    2003-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

  1. Eddy current losses in ferromagnetic laminations

    SciTech Connect

    Serpico, C. [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States)] [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States); Visone, C. [Department of Electrical Engineering, University of Naples ''Federico II'', I-80152 Napoli, (Italy)] [Department of Electrical Engineering, University of Naples ''Federico II'', I-80152 Napoli, (Italy); Mayergoyz, I. D. [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States)] [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States); Basso, V. [IEN Galileo Ferraris, Corso M. d'Azeglio 41, I-10125 Torino, (Italy)] [IEN Galileo Ferraris, Corso M. d'Azeglio 41, I-10125 Torino, (Italy); Miano, G. [Department of Electrical Engineering, University of Naples ''Federico II'', I-80152 Napoli, (Italy)] [Department of Electrical Engineering, University of Naples ''Federico II'', I-80152 Napoli, (Italy)

    2000-05-01

    It is demonstrated through the comparison of analytical, numerical, and experimental results that the existence of excess eddy current losses can be explained by the peculiar nature of the nonlinear diffusion of electromagnetic fields in magnetically nonlinear laminations. The essence of this peculiar nature is that nonlinear diffusion occurs as inward progress of almost rectangular profiles of magnetic flux density of variable height. Approximating actual profiles of magnetic flux density by rectangular ones, the problem of nonlinear diffusion can be treated analytically by using a simple model. The accuracy and the limit of applicability of the rectangular profile model are discussed by comparing its predictions with finite elements numerical solutions of nonlinear diffusion equation as well as with experimental results. (c) 2000 American Institute of Physics.

  2. Analysis of "Kiss" Bonds Between Composite Laminates

    NASA Astrophysics Data System (ADS)

    Poveromo, Scott L.; Earthman, James C.

    2014-06-01

    One of the leading challenges to designing lightweight, cost-effective bonded structures is to detect low shear strength "kiss" bonds where no other defects such as voids and cracks exist. To develop a nondestructive testing method that is sensitive to kiss bonds, standards need to be fabricated with known strength values. In the current work, we attempt to create kiss bonds in between carbon fiber composite laminates that have been bonded with epoxy film adhesive and epoxy paste adhesive. Based on ultrasonic testing, when creating true kiss bonds using film adhesives, a complete disbond could not be avoided because of thermally induced stresses during the high-temperature cure. However, further work demonstrated that kiss bonds can be formed using room-temperature curable epoxy paste adhesives by creating an amine blush on the epoxy surface or applying a release agent on the bonding surfaces.

  3. Diatoms in Historical Tsunami Deposits, Northern California, USA

    NASA Astrophysics Data System (ADS)

    Hemphill-Haley, E.; Loofbourrow, C.

    2013-12-01

    A fundamental challenge in using microfossils to differentiate paleotsunami deposits from those of other sources (storms, floods) is to identify characteristics that favor one mode of deposition over the other. The silt- to sand-size siliceous hard parts (valves) of diatoms are commonly found as transported particles in tsunami deposits, but logically, may also be found in other types of coastal deposits of the same grain size. To date, observations on diatom preservation and provenance have been invoked as supporting evidence for paleotsunami deposits. These observations can be tested and refined by detailed observations of diatom assemblages in recent, well-documented tsunami deposits. As a component of the U.S. Geological Survey Science Application for Risk Reduction (SAFRR) project, diatoms were examined in two historical tsunami deposits on the central and northern California coast: the 1946 deposit on the north end of Half Moon Bay (37.5N) and the 1964 deposit about 10 km south of Crescent City (41.7N). Both tsunamis were the result of distant-source events across the Pacific Ocean from California: the M 8.1 Eastern Aleutians Islands earthquake (1946) and the M 9.2 Alaska earthquake (1964). At both localities tsunami inundation was documented by eyewitness accounts. The deposits are now preserved in the shallow subsurface as ~1-10 cm thick layers of silt and sand intercalated in peaty marsh or clay-rich lagoon deposits. These historical tsunami deposits are particularly useful for documenting characteristics of entrained diatom assemblages for comparison to paleotsunami deposits. First, the deposits consist of mostly fine sand and silt, and therefore are an appropriate particle size for containing diatoms. Second, although they are recent enough to have been documented by eyewitness accounts, they are also old enough to have been altered by natural geological processes (e.g., burial, compaction, taphonomic affects on diatom valves) as would be found in paleotsunami deposits. Finally, although they are both the result of deposition by a distant-source tsunami at a coastal location not affected by coincident earthquake deformation (i.e., non-subsiding coast), they accumulated and were preserved in different kinds of coastal environments, and therefore the diatom records for each are different. At Half Moon Bay, the 1946 tsunami swept across a shallow brackish lagoon and salt marsh, leaving a deposit of clean, very fine sand containing large, allochthonous epipsammic diatoms consistent with landward-directed transport from the adjacent shallow marine nearshore. Where the deposit settled out and was later buried by clay-rich lagoon deposits, both the tsunami sand layer and entrained diatoms are well preserved. In contrast to the open, preservation-conducive lagoon environment at Half Moon Bay, the 1964 tsunami south of Crescent City inundated a freshwater marsh with thick stands of vegetation. The resultant paleotsunami deposit is limited in lateral extent, and dominantly contains well-preserved freshwater diatoms that mask obvious evidence of marine inundation.

  4. Distribution of Diatoms and Development of Diatom-Based Models for Inferring Salinity and Nutrient Concentrations in Florida Bay and Adjacent Coastal Wetlands of South Florida (USA)

    Microsoft Academic Search

    Anna Wachnicka; Evelyn Gaiser; Laurel Collins; Thomas Frankovich; Joseph Boyer

    2010-01-01

    The composition and distribution of diatom algae inhabiting estuaries and coasts of the subtropical Americas are poorly documented,\\u000a especially relative to the central role diatoms play in coastal food webs and to their potential utility as sentinels of environmental\\u000a change in these threatened ecosystems. Here, we document the distribution of diatoms among the diverse habitat types and long\\u000a environmental gradients

  5. Diatomic infrared gasdynamic laser permits selection of wavelengths

    NASA Technical Reports Server (NTRS)

    Mckenzie, R. L.

    1972-01-01

    Laser utilizes infrared-active diatomic gas which emits laser energy from numerous upper vibrational levels. Wavelengths depend on particular vibration-rotation transitions and have been obtained throughout the band between 4.78 and 5.4 microns, for example, when using carbon monoxide.

  6. FLUORESCENCE QUENCHING AND THE DIADINOXANTHIN CYCLE IN A MARINE DIATOM

    EPA Science Inventory

    The diadinoxanthin cycle (DD-cycle) in chromophyta algae involves the interconversion of two carotenoids, diadinoxanthin (DD) and diatoxanthin (DT). e investigated the kinetics of light-induced DD-cycling in the marine diatom Phaeodactylum triconutum and its role in dissipating e...

  7. Self-Entanglement and the Dissociation of Homonuclear Diatomic Molecules

    SciTech Connect

    Gonis, Antonios [ORNL] [ORNL; Zhang, Xiaoguang [ORNL] [ORNL; Nicholson, Don M [ORNL] [ORNL; Stocks, George Malcolm [ORNL] [ORNL

    2014-01-01

    The concept of self-entanglement is introduced to describe a mixed state or ensemble density as a pure state in an augmented Hilbert space formed by the products of the individual states forming a mixed state (or ensemble). We use this representation of mixed states to show that upon dissociation a neutral homonuclear diatomic molecule will separate into two neutral atoms.

  8. Continental erosion and the Cenozoic rise of marine diatoms.

    PubMed

    Cermeo, Pedro; Falkowski, Paul G; Romero, Oscar E; Schaller, Morgan F; Vallina, Sergio M

    2015-04-01

    Marine diatoms are silica-precipitating microalgae that account for over half of organic carbon burial in marine sediments and thus they play a key role in the global carbon cycle. Their evolutionary expansion during the Cenozoic era (66 Ma to present) has been associated with a superior competitive ability for silicic acid relative to other siliceous plankton such as radiolarians, which evolved by reducing the weight of their silica test. Here we use a mathematical model in which diatoms and radiolarians compete for silicic acid to show that the observed reduction in the weight of radiolarian tests is insufficient to explain the rise of diatoms. Using the lithium isotope record of seawater as a proxy of silicate rock weathering and erosion, we calculate changes in the input flux of silicic acid to the oceans. Our results indicate that the long-term massive erosion of continental silicates was critical to the subsequent success of diatoms in marine ecosystems over the last 40 My and suggest an increase in the strength and efficiency of the oceanic biological pump over this period. PMID:25831504

  9. CHECKLIST OF DIATOMS FROM THE LAURENTIAN GREAT LAKES

    EPA Science Inventory

    An updated diatom checklist for the Great Lakes is provided. The present checklist supplants the preliminary checklist published in The Journal for Great Lakes Research in 1978 and effectively represents a 20-year update. A series of procedures were used in this update which incl...

  10. RESEARCH Open Access Digital expression profiling of novel diatom

    E-print Network

    Paris-Sud XI, Universit de

    RESEARCH Open Access Digital expression profiling of novel diatom transcripts provides insight algae [2-4]. As a consequence, these organisms derive from the combination of three distinct nuclear://genomebiology.com/2010/11/8/R85 2010 Maheswari et al; licensee BioMed Central Ltd. This is an open access article

  11. A Diatom-based, Paleolimnological Study Of Rush Lake, Wisconsin

    NASA Astrophysics Data System (ADS)

    Fischer-Guex, L.; Pillsbury, R. W.; Mode, W.

    2005-05-01

    Rush Lake, located in Winnebago County, Wisconsin, is a shallow, eutrophic, lake/wetland dominated by cattails. This system has historically been important for fishing and waterfowl production. But recently the general public view the lake as degraded from increased sedimentation, contamination from lead shot, and perceived reduction in fish and wildlife. A sediment core (374cm) was taken by employing a modified Livingstone piston corer. The core sample was dated with carbon-14 yielding a date at the base of the core of 4110 +/- 40 yr. B.P. The core sediments were sampled for diatoms starting at 5cm for every 10cm after that (37 samples). Diatoms were counted for a total of 300 per sample. Typical of shallow lakes, the core showed signs of being extensively reworked. Despite this, multivariate analysis of diatoms (PCA) suggests that this system has become more eutrophic. This is consistent with a pollen analysis and is likely due to agricultural activities in the watershed. There is no evidence (i.e., increase in % planktonic diatoms) that the lake had ever developed a pelagic zone for an extended period of time. Results of this study may be useful in making future management decisions to restore Rush Lake.

  12. Human error and quality assurance in diatom analysis

    E-print Network

    Kelly, M.G.; Bayer, M.M.

    Kelly,M.G. Bayer,M.M. Hürlimann,J. Telford,R.J. In: Automatic Diatom Identification. Series in Machine Perception and Artificial Intelligence. Eds. du Buf, J M H & Bayer, M M. pp 75-92 World Scientific

  13. The evolutionary species pool hypothesis and patterns of freshwater diatom

    E-print Network

    Pither, Jason

    the unimodal relationship between diatom species richness and lake pH within the context of the evolutionary spatial availabilities of historical pH conditions among freshwater lakes. We also determine whether local that occurred in at least 10 of the 234 lakes, four different measures of PSPs were calculated along the pH

  14. CHECKLIST OF DIATOMS FROM THE LAURENTIAN GREAT LAKES

    EPA Science Inventory

    An updated diatom (Bacillariophyta) checklist for the Great Lakes has been completed (J. Great Lakes Res. 1999) and supplants the preliminary checklist (J. Great Lakes Res. 1978). The present list is effectively a 20-year update. The updated list is based upon: 1) the 1978 checkl...

  15. The Buoyancy of Plankton Diatoms: A Problem of Cell Physiology

    Microsoft Academic Search

    F. Gross; E. Zeuthen

    1948-01-01

    Observations on pure cultures of diatoms and the results of centrifuge experiments showed that under optimal conditions the vegetative cells have the same specific gravity as sea water. The specific gravity of resting spores is significantly higher than that of sea water. Hence the specific gravity of the cell sap which fills the bulk of the vegetative cell and is

  16. Observation of damage growth in compressively loaded laminates

    NASA Technical Reports Server (NTRS)

    Knauss, W. G.; Babcock, C. D.; Chai, H.

    1983-01-01

    Graphite/epoxy laminates have a definite advantage with respect to the strength-to-weight relation over many standard engineering materials used in aerospace applications. However, this advantage is somewhat reduced by the sensitivity of these laminates to operational hazards, which include a low-velocity impact by foreign objects. Investigations conducted by Chai (1982) and Knauss et al. (1980) have been concerned with the growth of impact damage in compressively loaded laminates, and the visualization of such an impact damage. The present study represents a condensation of parts of these investigations, taking into account a determination of the damage-growth mechanism via real-time recording of the impact event. The material considered, a T300/5208 graphite/epoxy laminate, is typical of the configuration proposed for future heavily loaded primary structures. It has stiffness properties similar to those of the wing skins in existing transport aircraft.

  17. A micromechanics-based mesomodel for unidirectional laminates in compression

    E-print Network

    Paris-Sud XI, Université de

    A micromechanics-based mesomodel for unidirectional laminates in compression N. Feld1 , O. Allix1. The improvements are based on micromechanical studies of the kinking phenomenon. Several sources of kinking

  18. Optimal Synthesis of Hot Composite Laminates with Interphase Layers

    NASA Technical Reports Server (NTRS)

    Rabzak, Christopher; Saravanos, Dimitris A.; Chamis, Christos C.

    1993-01-01

    A method for the optimal grading of a single interphase layer in metal matrix composite laminates for the minimization of residual stresses is described. The capability to simultaneously tailor some fabrication parameters is also incorporated. Applications for unidirectional, cross-ply and quasi-isotropic Graphite/Copper laminates are investigated to assess the potential of interphase layer in reducing matrix residual stresses in various laminate configurations. Simultaneous optimization of interphase and fabrication characteristics appears to be more effective in decreasing residual stresses. The results also indicate that the interphase layer is more effective in lowering residual stresses in unidirectional composites and selectively within individual plies of a laminate. Embedded interphase layers in all the plies did not produce a significant global reduction in residual stresses.

  19. Vibration analysis of composite laminate plate excited by piezoelectric actuators.

    PubMed

    Her, Shiuh-Chuan; Lin, Chi-Sheng

    2013-01-01

    Piezoelectric materials can be used as actuators for the active vibration control of smart structural systems. In this work, piezoelectric patches are surface bonded to a composite laminate plate and used as vibration actuators. A static analysis based on the piezoelectricity and elasticity is conducted to evaluate the loads induced by the piezoelectric actuators to the host structure. The loads are then employed to develop the vibration response of a simply supported laminate rectangular plate excited by piezoelectric patches subjected to time harmonic voltages. An analytical solution of the vibration response of a simply supported laminate rectangular plate under time harmonic electrical loading is obtained and compared with finite element results to validate the present approach. The effects of location and exciting frequency of piezoelectric actuators on the vibration response of the laminate plate are investigated through a parametric study. Numerical results show that modes can be selectively excited, leading to structural vibration control. PMID:23529121

  20. Tensile stress-strain behavior of hybrid composite laminates

    NASA Technical Reports Server (NTRS)

    Kennedy, J. M.

    1983-01-01

    A study was made of the stress-strain response of several hybrid laminates, and the damage was correlated with nonlinear stress-strain response and ultimate strength. The fibers used in the laminates were graphite, S-glass, and Kevlar. Some laminates with graphite fibers had perforated Mylar film between plies, which lowered the interlaminar bond strength. The laminate configurations were chosen to be like those of buffer strips in large panels and fracture coupons. Longitudinal and transverse specimens were loaded in tension to failure. Some specimens were radiographed to reveal damage due to edge effects. Stress-strain response is discussed in terms of damage shown by the radiographs. Ultimate strengths are compared with simple failure criteria, one of which account for damage.

  1. Analysis of a unidirectional, symmetric buffer strip laminate with damage

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1984-01-01

    A method for predicting the fracture behavior of hybrid buffer strip laminates is presented in which the classical shear-lag model is used to represent the shear stress distribution between adjacent fibers. The method is demonstrated by applying it to a notched graphite/epoxy laminate, and the results show clearly the manner in which the most efficient combination of buffer strip properties can be selected in order to arrest the crack. The ultimate failure stress of the laminate is plotted vs the buffer strip width. It is shown that in the case of graphite-epoxy and S-glass epoxy laminates, the optimum buffer strip spacing to width ratio should be about four to one.

  2. Laminated rare earth structure and method of making

    DOEpatents

    Senor, David J [West Richland, WA; Johnson, Roger N [Richland, WA; Reid, Bruce D [Pasco, WA; Larson, Sandra [Richland, WA

    2002-07-30

    A laminated structure having two or more layers, wherein at least one layer is a metal substrate and at least one other layer is a coating comprising at least one rare earth element. For structures having more than two layers, the coating and metal substrate layers alternate. In one embodiment of the invention, the structure is a two-layer laminate having a rare earth coating electrospark deposited onto a metal substrate. In another embodiment of the invention, the structure is a three-layer laminate having the rare earth coating electrospark deposited onto a first metal substrate and the coating subsequently abonded to a second metal substrate. The bonding of the coating to the second metal substrate may be accomplished by hot pressing, hot rolling, high deformation rate processing, or combinations thereof. The laminated structure may be used in nuclear components where reactivity control or neutron absorption is desired and in non-nuclear applications such as magnetic and superconducting films.

  3. Nuclear lamins during gametogenesis, fertilization and early development

    NASA Technical Reports Server (NTRS)

    Maul, G. G.; Schatten, G.

    1986-01-01

    The distribution of lamins (described by Gerace, 1978, as major proteins of nuclear envelope) during gametogenesis, fertilization, and early development was investigated in germ cells of a mouse (Mus musculus), an echinoderm (Lytechinus variegatus), and the surf clam (Spisula solidissima) was investigated in order to determine whether the differences detected could be correlated with differences in the function of cells in these stages of the germ cells. In order to monitor the behavior of lamins, the gametes and embryos were labeled with antibodies to lamins A, C, and B extracted from autoimmune sera of patients with scleroderma and Lupus erythematosus. Results indicated that lamin B could be identified in nuclear envelopes on only those nuclei where chromatin is attached and where RNA synthesis takes place.

  4. Fatigue of notched fiber composite laminates. Part 1: Analytical model

    NASA Technical Reports Server (NTRS)

    Mclaughlin, P. V., Jr.; Kulkarni, S. V.; Huang, S. N.; Rosen, B. W.

    1975-01-01

    A description is given of a semi-empirical, deterministic analysis for prediction and correlation of fatigue crack growth, residual strength, and fatigue lifetime for fiber composite laminates containing notches (holes). The failure model used for the analysis is based upon composite heterogeneous behavior and experimentally observed failure modes under both static and fatigue loading. The analysis is consistent with the wearout philosophy. Axial cracking and transverse cracking failure modes are treated together in the analysis. Cracking off-axis is handled by making a modification to the axial cracking analysis. The analysis predicts notched laminate failure from unidirectional material fatique properties using constant strain laminate analysis techniques. For multidirectional laminates, it is necessary to know lamina fatique behavior under axial normal stress, transverse normal stress and axial shear stress. Examples of the analysis method are given.

  5. Progressive Failure Analysis Methodology for Laminated Composite Structures

    NASA Technical Reports Server (NTRS)

    Sleight, David W.

    1999-01-01

    A progressive failure analysis method has been developed for predicting the failure of laminated composite structures under geometrically nonlinear deformations. The progressive failure analysis uses C(exp 1) shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms and several options are available to degrade the material properties after failures. The progressive failure analysis method is implemented in the COMET finite element analysis code and can predict the damage and response of laminated composite structures from initial loading to final failure. The different failure criteria and material degradation methods are compared and assessed by performing analyses of several laminated composite structures. Results from the progressive failure method indicate good correlation with the existing test data except in structural applications where interlaminar stresses are important which may cause failure mechanisms such as debonding or delaminations.

  6. Dynamic response of monolithic and laminate/particulate reactive mixtures

    E-print Network

    Wei, Chung-Ting

    2011-01-01

    at the reaction front, the heat dissipation rate is thereactions in the Ni/Al laminates are significantly influenced by the heat dissipation rate,reaction at ambient temperature. In this approach, the rate of the heat

  7. Calculation of the room-temperature shapes of unsymmetric laminates

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.

    1981-01-01

    A theory explaining the characteristics of the cured shapes of unsymmetric laminates is presented. The theory is based on an extension of classical lamination theory which accounts for geometric nonlinearities. A Rayleigh-Ritz approach to minimizing the total potential energy is used to obtain quantitative information regarding the room temperature shapes of square T300/5208 (0(2)/90(2))T and (0(4)/90(4))T graphite-epoxy laminates. It is shown that, depending on the thickness of the laminate and the length of the side the square, the saddle shape configuration is actually unstable. For values of length and thickness that render the saddle shape unstable, it is shown that two stable cylindrical shapes exist. The predictions of the theory are compared with existing experimental data.

  8. Nonlinear analysis of laminated fibrous composites. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Renieri, G. D.; Herakovich, C. T.

    1976-01-01

    A computerized analysis of the nonlinear behavior of fibrous composite laminates including axial loading, thermal loading, temperature dependent properties, and edge effects is presented. Ramberg-Osgood approximations are used to represent lamina stress-strain behavior and percent retention curves are employed to model the variation of properties with temperature. Balanced, symmetric laminates comprised of either boron/epoxy, graphite/epoxy, or borsic-aluminum are analyzed using a quasi-three-dimensional finite element analysis. Results are presented for the interlaminar stress distributions in cross-ply, angle-ply, and more complex laminates. Nonlinear stress-strain curves for a variety of composite laminates in tension and compression are obtained and compared to other existing theories and experimental results.

  9. Mechanics of fatigue damage in titanium-graphite hybrid laminates

    E-print Network

    Burianek, Dennis Arthur

    2001-01-01

    Titanium-graphite hybrid laminates are being developed for high-temperature aerospace applications. Experimental observations have indicated that cracks in the titanium facesheets initiate at free edges as well as in areas ...

  10. Plasma Citrulline Levels in Horses at Risk of Acute Laminitis

    E-print Network

    Jackson, Amy Lynn

    2013-04-10

    Laminitis is a painful and irreversible disease in horses in which the soft tissue structures of the foot, called the laminae (connecting the coffin bone to the hoof wall), lose blood flow and deteriorate. Without the support of these laminae...

  11. Stairway fracture architecture in laminated to finely stratified rocks

    NASA Astrophysics Data System (ADS)

    Maggi, Matteo; Cianfarra, Paola; Salvini, Francesco

    2014-05-01

    In this work we present the result of a study dealing on the architecture of fractures in laminated rocks, where they develop accordingly to a stairway architecture. On a section perpendicular to the sedimentary layering/structure intersection, this architecture consists of stepping fracture segments running parallel to the lamination/layering (LaP) connected by ramp segments (R) cutting across the laminations. The presence of lamination produces an anisotropy that deviates the average fracture propagation. The presence of LaP segments strongly influences the fracture induced permeability in these rocks by increasing connectivity. These fractures are formed by either the coalescence of individual fractures (representing the ramp segments) or as the result of a single propagating fracture. Stairway fractures are likely to form during syn-diagenetic conditions. Depending on the original lamination dip, a component of rock sliding may trigger or enhance the fracturing process. The architecture of stairway fractures is parameterized by the L/R ratio (the ratio between the lengths of the Ramp and LaP segments), the original lamination dip, and the cut-off angle (the angle between the ramp segment of the fracture and the lamination), in turn depending from the stress regime. Successive tilting may tilt the original lamination dip. In this view, the cut-off angle results a particularly suited parameter being related to the interplay between the rheology of the layers and the stress conditions at failure. A physical model of stairway fractures has been developed considering the effect of the rheological contrast between the layer and the intra-layer infilling, the fluid overpressure and the overburden. The model has been successfully applied to laminated rocks outcrops. The rheological parameters needed to match the observed geometry were obtained using a Montecarlo approach. The obtained rheological parameters are comparable with those presented in the literature and justify the LaP/Ramp proposed model. Two distinct behaviors were found and quantified depending on the original lamination/layers dip. Fluid pressure plays an important role in the development of the LaP segments. Resulting model may be applied to model fracture-induced permeability in laminated fluid reservoirs.

  12. Research on the Bistablity of FGM Laminate Plates

    Microsoft Academic Search

    Zheng Zhang; Yumei Bao; Hongxia Sun

    2010-01-01

    Bi-stable functionally graded material (FGM) laminated plates are studied in this paper. Considering the bistablity, the isotropic and anisotropic composite laminate plates are analyzed. The numerical results of different FGM under different loading are compared with homogeneous materials by using continuous graded thickness integration rule of shell element. Then, the bistablity of different rotation angle layered composites including [-45\\/45], [0\\/90],

  13. Determination of the technical constants of laminates in oblique directions

    NASA Technical Reports Server (NTRS)

    Vidouse, F.

    1979-01-01

    An off-axis tensile test theory based on Hooke's Law is applied to glass fiber reinforced laminates. A corrective parameter dependent on the characteristics of the strain gauge used is introduced by testing machines set up for isotropic materials. Theoretical results for a variety of strain gauges are compared with those obtained by a finite element method and with experimental results obtained on laminates reinforced with glass.

  14. Microstress prediction in composite laminates with high stress gradients

    Microsoft Academic Search

    P. Hutapea; F. G. Yuan; N. J. Pagano

    2003-01-01

    The objective of this research is to develop a macroscopic theory, which can provide the connection between macro-mechanics and micro-mechanics in characterizing the micro-stress of composite laminates in regions of high macroscopic stress gradients. The micro-polar theory, a class of higher-order elasticity theory, of composite laminate mechanics is implemented in a well-known PipesPagano free edge boundary problem. The micro-polar homogenization

  15. Dielectric, ferroelectric, magnetic, and magnetoelectric properties of multiferroic laminated composites

    Microsoft Academic Search

    N. Cai; J. Zhai; C.-W. Nan; Y. Lin; Z. Shi

    2003-01-01

    Multiferroic laminated composites consisting of lead-zirconate titanate (PZT)\\/polyvinylidene-fluoride (PVDF) particulate composite layers and Tb-Dy-Fe alloy (Terfenol-D)\\/PVDF particulate composite layers, prepared by a simple hot-molding technique, were reported. In the laminated composites, the polymer PVDF is inert and used just as a binder. The measured dielectric, ferroelectric, magnetic, and magnetoelectric properties demonstrate strong dependence on volume fraction f of the PVDF

  16. Pin and bolt bearing strength of fibreglass\\/aluminium laminates

    Microsoft Academic Search

    G. Caprino; A. Squillace; G. Giorleo; L. Nele; L. Rossi

    2005-01-01

    An experimental investigation was carried out on a fibreglass\\/aluminium (FGA) laminate in order to characterise its behaviour under pin- and bolt-bearing conditions. In pin bearing, the limit width-to-diameter and edge distance-to-diameter ratios necessary to avoid unsafe failure modes were lower than those usually quoted for classical laminates. A simple model to design safe pin-bearing joints, previously proposed for fibre-reinforced plastics,

  17. Design of Chipless RFID Tag for Operation on Flexible Laminates

    Microsoft Academic Search

    Stevan Preradovic; Nemai C. Karmakar

    2010-01-01

    A fully printable chipless RFID tag on a 90-??m-thin Taconic TF290 laminate is presented. The tag consists of two crosspolarized ultrawideband (UWB) antennas and a multiresonating circuit. The data encoding is performed in the multiresonating circuit, which is comprised of multiple stopband spiral resonators. The resonators are optimized to operate on flexible laminate using two optimization techniques. Since TF290 has

  18. Laminated microchannel devices, mixing units and method of making same

    DOEpatents

    Bennett, Wendy D [Kennewick, WA; Hammerstrom, Donald J [West Richland, WA; Martin, Peter M [Kennewick, WA; Matson, Dean W [Kennewick, WA

    2002-10-17

    A laminated microchannel device is described in which there is a unit operation process layer that has longitudinal channel. The longitudinal channel is cut completely through the layer in which the unit process operation resides. Both the device structure and method of making the device provide significant advantages in terms of simplicity and efficiency. A static mixing unit that can be incorporated in the laminated microchannel device is also described.

  19. Correlation of surface sediment diatoms with the present lake water pH in 28 Algoma lakes, Ontario, Canada

    Microsoft Academic Search

    Sushil S. Dixit; Mike D. Dickman

    1986-01-01

    The surface sediment diatom analysis of 28 Algoma lakes (pH 4.408.13) indicates that even though each lake has a widely different aquatic environment and characteristic diatom assemblage, a definite relationship exists between the lake water pH and their diatom assemblages. In the acidic lakes acidobiontic and acidophilous diatom species predominate whereas in circumneutral and alkaline lakes circumneutral and alkaliphilous diatoms

  20. Diatom proteomics reveals unique acclimation strategies to mitigate Fe limitation.

    PubMed

    Nunn, Brook L; Faux, Jessica F; Hippmann, Anna A; Maldonado, Maria T; Harvey, H Rodger; Goodlett, David R; Boyd, Philip W; Strzepek, Robert F

    2013-01-01

    Phytoplankton growth rates are limited by the supply of iron (Fe) in approximately one third of the open ocean, with major implications for carbon dioxide sequestration and carbon (C) biogeochemistry. To date, understanding how alteration of Fe supply changes phytoplankton physiology has focused on traditional metrics such as growth rate, elemental composition, and biophysical measurements such as photosynthetic competence (Fv/Fm). Researchers have subsequently employed transcriptomics to probe relationships between changes in Fe supply and phytoplankton physiology. Recently, studies have investigated longer-term (i.e. following acclimation) responses of phytoplankton to various Fe conditions. In the present study, the coastal diatom, Thalassiosira pseudonana, was acclimated (10 generations) to either low or high Fe conditions, i.e. Fe-limiting and Fe-replete. Quantitative proteomics and a newly developed proteomic profiling technique that identifies low abundance proteins were employed to examine the full complement of expressed proteins and consequently the metabolic pathways utilized by the diatom under the two Fe conditions. A total of 1850 proteins were confidently identified, nearly tripling previous identifications made from differential expression in diatoms. Given sufficient time to acclimate to Fe limitation, T. pseudonana up-regulates proteins involved in pathways associated with intracellular protein recycling, thereby decreasing dependence on extracellular nitrogen (N), C and Fe. The relative increase in the abundance of photorespiration and pentose phosphate pathway proteins reveal novel metabolic shifts, which create substrates that could support other well-established physiological responses, such as heavily silicified frustules observed for Fe-limited diatoms. Here, we discovered that proteins and hence pathways observed to be down-regulated in short-term Fe starvation studies are constitutively expressed when T. pseudonana is acclimated (i.e., nitrate and nitrite transporters, Photosystem II and Photosystem I complexes). Acclimation of the diatom to the desired Fe conditions and the comprehensive proteomic approach provides a more robust interpretation of this dynamic proteome than previous studies. PMID:24146769

  1. Fossilized diatoms in meteorites from recent falls in Sri Lanka

    NASA Astrophysics Data System (ADS)

    Hoover, Richard B.; Wallis, Jamie; Wickramarathne, Keerthi; Samaranayake, Anil; Williams, George; Jerman, Gregory; Wallis, D. H.; Wickramasinghe, N. C.

    2013-09-01

    On December 29, 2012, a bright yellow and green fireball was observed to disintegrate over the Polonnaruwa District of North Central, Sri Lanka. Many low density, black stones were recovered soon after the observed fall from rice paddy fields near the villages of Aralaganwila and Dimbulagala. These stones were initially studied by optical microscopy methods at the Medical Research Institute in Colombo, Sri Lanka. Soon thereafter, samples were sent to the UK and to the United States. More extensive Field Emission Scanning Electron Microscopy studies were then carried out at Cardiff University and the NASA/Marshall Space Flight Center. The physico-chemical properties, elemental abundances, mineralogy and stable isotope data clearly indicate that these stones are non-terrestrial. Freshly fractured interior surfaces of the black stones have also been observed to contain the remains of fossilized diatom. Many of the diatom frustules are clearly embedded in the meteorite rock matrix and exhibit nitrogen levels below the EDX detection limits. Some of the fossil diatoms are araphid marine pennates and planktonic forms that are inconsistent with conditions associated with rice paddy fields. These observations indicate the fossilized diatoms are indigenous to the meteorites rather than post-arrival biological contaminants. The carbon content and mineralogy suggests that these stones may represent a previously ungrouped clan of carbonaceous meteorites. The extremely low density (~0.6) of the stones and their observed mineralogy was inconsistent with known terrestrial rocks (e.g., pumice, diatomite and fulgurites). The minerals detected suggest that the parent body of the Polonnaruwa stones may have been the nucleus of a comet. These observations are interpreted as supporting the Hoyle-Wickramasinghe Panspermia hypothesis and the hypothesis that diatoms and other microorganisms might be capable of living and growing in water ice and brines in comets.

  2. Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.; Smeltzer, Stanley S., III

    2000-01-01

    An analytical, parametric study of the attenuation of bending boundary layers or edge effects in balanced and unbalanced, symmetrically and unsymmetrically laminated thin cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize and quantify the effects of laminate orthotropy and laminate anisotropy on the bending boundary-layer decay length in a very general and encompassing manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all the laminate constructions considered, the results show that the differences between results that were obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that in some cases neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and in other cases it results in an overestimation.

  3. Three dimensional inelastic finite element analysis of laminated composites

    NASA Technical Reports Server (NTRS)

    Griffin, O. H., Jr.; Kamat, M. P.

    1980-01-01

    Formulations of the inelastic response of laminated composites to thermal and mechanical loading are used as the basis for development of the computer NALCOM (Nonlinear Analysis of Laminated Composites) computer program which uses a fully three dimensional isoparametric finite element with 24 nodes and 72 degrees of freedom. An incremental solution is performed with nonlinearities introduced as pseudoloads computed for initial strains. Equilibrium iteration may be performed at every step. Elastic and elastic-plastic response of boron/epoxy and graphite/epoxy graphite/epoxy and problems of curing 0/90 sub s Gr/Ep laminates with and without circular holes are analyzed. Mechanical loading of + or - 45sub s Gr/Ep laminates is modeled and symmetry conditions which exist in angle-ply laminates are discussed. Results are compared to experiments and other analytical models when possible. All models are seen to agree reasonably well with experimetnal results for off-axis tensile coupons. The laminate analyses show the three dimensional effects which are present near holes and free corners.

  4. Stochastic damage evolution modeling in laminates. Ph.D. Thesis

    SciTech Connect

    Dzenis, Y.A.

    1994-01-01

    A stochastic mesomechanics model has been developed for damage accumulation analysis in advanced laminated composites. The model is based on a theory of excursions of random process beyond the limiting bounds. Stochastic strains in the laminate subjected to random Gaussian in-plane loading are calculated using lamination theory and random functions theory. Probabilistic variation of stiffness and strength characteristics of plies are used in the analysis. A stochastic version of maximum strain failure criterion is applied for damage probability calculation. A mesovolume concept is utilized in modeling stiffness degradation. The model is verified experimentally based on the available data. Capabilities of the model are illustrated by predictions of damage accumulation and failure in a Kevlar/epoxy (0/ +/- 30/90){sub s} laminate under quasistationary, long-term stationary, and cyclic loading. Effects of loading rate, deviation, stationary level and cyclic amplitude on damage evolution are discussed. High-cycle fatigue behavior of laminate is calculated utilizing the observed stages in failure accumulation under the cyclic loading. Percolation type analysis of damage morphology is performed for the inhomogeneous anisotropic media. The model and computer codes developed can be incorporated into structural analysis software and used in design of laminated structures.

  5. The effect of lamination angle on polymer retention

    SciTech Connect

    Gao, H.W.

    1992-09-01

    Polymer retention may be affected by the reservoir geological structure due to lamination of the mineral surfaces. These laminae are very prevalent in Class I reservoirs. To account for the effect of lamination angle on polymer retention, several corefloods with three fired, rectangular, Berea sandstone cores were conducted. The three cores were cut at three different angles, 0, 30, and 90 degrees, with respect to the direction of laminations. A multiple slug retention method was used to determine the retention of a biopolymer in each core. Tracer tests were conducted before and after the biopolymer flow to determine how the retained biopolymer affected the fluid advance. A computed tomography (CT) scanning method was used to monitor the advance of the tracer. All corefloods and tracer tests were conducted at low flow rates similar to that in reservoirs. Coreflood tests revealed that polymer retention, which was mainly caused by mechanical entrapment, was higher in cores that had laminations parallel to the direction of flow than in cores that had crossbed laminae. In cores that had crossbed laminae, polymer retention increased with an increase in the lamination angle. Retained polymer is harmful to the stability of fluid front in cores that have laminations parallel to the direction of flow, but is helpful in cores that have crossbed laminae.

  6. Association of the glycoxidative stress marker pentosidine with equine laminitis.

    PubMed

    Valle, E; Storace, D; Sanguineti, R; Carter, R; Odetti, P; Geor, R; Bergero, D

    2013-06-01

    Ponies suffering from recurrent episodes of laminitis when grazed at pasture (pasture-associated laminitis) exhibit phenotypes similar to those associated with human metabolic syndrome. In humans, evidence suggests that the obesity-related morbidities associated with metabolic syndrome, including diabetes and cardiovascular disease, are caused by an increase in the production of advanced glycoxidation end-products (AGEs). These end-products have been recognised as putative pro-inflammatory mediators and are considered a 'risk factor' for human health. However, the evaluation of AGEs in laminitic ponies has not been explored. The aim of this study was to compare plasma concentrations of the AGE pentosidine (PENT) in ponies presenting with clinical features of equine metabolic syndrome (EMS) with a history of recent laminitis and/or showing signs of laminitis at the time of sampling (LP) with those with no prior history of clinical laminitis (NL). Age, body condition score (BCS) and bodyweight were recorded and blood samples collected for the measurement of plasma concentrations of PENT, glucose, insulin, triglycerides (TG), non-esterified fatty acids (NEFA) and cortisol. Insulin sensitivity was assessed by the reciprocal of the square root of insulin (RISQI) and the insulin:glucose ratio. Plasma PENT concentrations were twofold higher (P<0.005) in LP than in NL ponies. Significant (P<0.05) correlations were also evident between PENT and insulin, RISQI, TG and age. These preliminary findings are consistent with the hypothesis that glycoxidation in laminitis is associated with EMS. PMID:23206662

  7. A 2D p-version LSFEF for laminated composites incorporating laminate physics

    SciTech Connect

    Nayak, H.V.; Surana, K.S. [Univ. of Kansas, Lawrence, KS (United States). Dept. of Mechanical Engineering

    1998-12-31

    This paper presents a 2D p-version least squares finite element formulation for laminated composites incorporating the physics of laminated behavior. At the interface between two laminas of dissimilar materials the authors have continuity of displacements u, v, stresses {sigma}{sub yy}, {tau}{sub xy}, and strain {var_epsilon}{sub xx}, while the stress {sigma}{sub xx} and the strains {var_epsilon}{sub yy} and {gamma}{sub xy} are discontinuous. Thus, a finite element formulation, incorporating the physics of laminate behavior, would require interpolation of u, v, {var_epsilon}{sub xx}, {sigma}{sub yy}, {tau}{sub xy} instead of u, v {sigma}{sub xx}, {sigma}{sub yy} and {tau}{sub xy} which is generally the case in most LSFE formulations. In the p-version LSFEF presented here, the authors interpolate u, v (primary variables) and {var_epsilon}{sub xx}, {sigma}{sub yy}, {tau}{sub xy} (auxiliary variables) using equal order p-version C{sup 0} interpolations which would ensure interlamina continuity of these components. When the mating lamina properties are different, interlamina discontinuity of {sigma}{sub xx}, {var_epsilon}{sub yy} and {gamma}{sub xy} is automatically generated due to dissimilar material properties of the laminas. In this formulation interlamina jumps in {sigma}{sub xx}, {var_epsilon}{sub yy} and {gamma}{sub xy} do not constitute singularities, hence mesh refinements and higher p-levels are not needed in the vicinity of inter-lamina boundaries.

  8. Progressive Fracture of Laminated Composite Stiffened Plate

    NASA Technical Reports Server (NTRS)

    Gotsis, Pascalis K.; Chamis, Christos C.; David, Kostantinos; Abdi, Frank

    2007-01-01

    Laminated fiber-reinforced composite stiffened plate with [0/90/plus or minus 45]s plies made of S-Glass/epoxy are evaluated via computational simulation to study damage and fracture progression. The loads are pressure and temperature which varies from 21 to 65.5 C (case I) and from 143.3 to 21 C (case II). An integrated computer code is used for the simulation of the damage progression. Results show that damage initiation begins at low load level, with matrix cracking at the 0 deg. (bottom and top) plies, fiber fracture at the bottom (0 deg.) ply and interply delamination at the top (0 deg. ) ply. Increasing the applied pressure, the damage growth is expended resulting in fracture through the thickness of the structure. At this stage, 90 percent of the plies damage at applied pressure 15.306 MPa for the case I and 15.036 MPa for the case II. After this stage the cracks propagate rapidly and the structure collapses.

  9. Crush testing, characterizing, and modeling the crashworthiness of composite laminates

    NASA Astrophysics Data System (ADS)

    Garner, David Michael, Jr.

    Research in the field of crashworthiness of composite materials is presented. A new crush test method was produced to characterize the crush behavior of composite laminates. In addition, a model of the crush behavior and a method for rank ordering the energy absorption capability of various laminates were developed. The new crush test method was used for evaluating the crush behavior of flat carbon/epoxy composite specimens at quasi-static and dynamic rates. The University of Utah crush test fixture was designed to support the flat specimen against catastrophic buckling. A gap, where the specimen is unsupported, allowed unhindered crushing of the specimen. In addition, the specimen's failure modes could be clearly observed during crush testing. Extensive crush testing was conducted wherein the crush force and displacement data were collected to calculate the energy absorption, and high speed video was captured during dynamic testing. Crush tests were also performed over a range of fixture gap heights. The basic failure modes were buckling, crack growth, and fracture. Gap height variations resulted in poorly, properly, and overly constrained specimens. In addition, guidelines for designing a composite laminate for crashworthiness were developed. Modeling of the crush behavior consisted of the delamination and fracture of a single ply or group of like plies during crushing. Delamination crack extension was modeled using the mode I energy release rate, G lc, where an elastica approach was used to obtain the strain energy. Variations in Glc were briefly explored with double cantilever beam tests wherein crack extension occurred along a multidirectional ply interface. The model correctly predicted the failure modes for most of the test cases, and offered insight into how the input parameters affect the model. The ranking method related coefficients of the laminate and sublaminate stiffness matrices, the ply locations within the laminate, and the laminate thickness. The ranking method correctly ordered the laminates tested in this study with respect to their energy absorption.

  10. 40 CFR 63.5865 - What data must I generate to demonstrate compliance with the standards for continuous lamination...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...compliance with the standards for continuous lamination/casting operations? 63.5865 Section...compliance with the standards for continuous lamination/casting operations? (a) For continuous lamination/casting affected sources...

  11. 40 CFR 63.5820 - What are my options for meeting the standards for continuous lamination/casting operations?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...meeting the standards for continuous lamination/casting operations? 63.5820...lamination line and each continuous casting line complies with the applicable...continuous lamination and continuous casting lines combined, comply...

  12. 40 CFR Table 11 to Subpart Wwww of... - Data Requirements for New and Existing Continuous Lamination and Continuous Casting Lines...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent...continuous lamination lines and continuous casting lines you must determine...

  13. 40 CFR 63.5865 - What data must I generate to demonstrate compliance with the standards for continuous lamination...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...the standards for continuous lamination/casting operations? 63.5865 Section 63...the standards for continuous lamination/casting operations? (a) For continuous lamination/casting affected sources complying with a...

  14. 40 CFR Table 11 to Subpart Wwww of... - Data Requirements for New and Existing Continuous Lamination and Continuous Casting Lines...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent Reduction...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent Reduction...continuous lamination lines and continuous casting lines you must determine the data in...

  15. 40 CFR 63.5865 - What data must I generate to demonstrate compliance with the standards for continuous lamination...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...the standards for continuous lamination/casting operations? 63.5865 Section 63...the standards for continuous lamination/casting operations? (a) For continuous lamination/casting affected sources complying with a...

  16. 40 CFR 63.5865 - What data must I generate to demonstrate compliance with the standards for continuous lamination...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...the standards for continuous lamination/casting operations? 63.5865 Section 63...the standards for continuous lamination/casting operations? (a) For continuous lamination/casting affected sources complying with a...

  17. 40 CFR Table 11 to Subpart Wwww of... - Data Requirements for New and Existing Continuous Lamination and Continuous Casting Lines...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent Reduction...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent Reduction...continuous lamination lines and continuous casting lines you must determine the data in...

  18. 40 CFR 63.5865 - What data must I generate to demonstrate compliance with the standards for continuous lamination...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...the standards for continuous lamination/casting operations? 63.5865 Section 63...the standards for continuous lamination/casting operations? (a) For continuous lamination/casting affected sources complying with a...

  19. 40 CFR 63.5820 - What are my options for meeting the standards for continuous lamination/casting operations?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...the standards for continuous lamination/casting operations? 63.5820 Section 63...the standards for continuous lamination/casting operations? You must use one or more...continuous lamination line and each continuous casting line complies with the applicable...

  20. 40 CFR Table 11 to Subpart Wwww of... - Data Requirements for New and Existing Continuous Lamination and Continuous Casting Lines...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent Reduction...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent Reduction...continuous lamination lines and continuous casting lines you must determine the data in...

  1. 40 CFR 63.5820 - What are my options for meeting the standards for continuous lamination/casting operations?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...the standards for continuous lamination/casting operations? 63.5820 Section 63...the standards for continuous lamination/casting operations? You must use one or more...continuous lamination line and each continuous casting line complies with the applicable...

  2. 40 CFR Table 11 to Subpart Wwww of... - Data Requirements for New and Existing Continuous Lamination and Continuous Casting Lines...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent Reduction...Existing Continuous Lamination and Continuous Casting Lines Complying With a Percent Reduction...continuous lamination lines and continuous casting lines you must determine the data in...

  3. 40 CFR 63.5820 - What are my options for meeting the standards for continuous lamination/casting operations?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...the standards for continuous lamination/casting operations? 63.5820 Section 63...the standards for continuous lamination/casting operations? You must use one or more...continuous lamination line and each continuous casting line complies with the applicable...

  4. 40 CFR 63.5820 - What are my options for meeting the standards for continuous lamination/casting operations?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...the standards for continuous lamination/casting operations? 63.5820 Section 63...the standards for continuous lamination/casting operations? You must use one or more...continuous lamination line and each continuous casting line complies with the applicable...

  5. Travelling-Wave Deceleration of Heavy Diatomic Molecules

    NASA Astrophysics Data System (ADS)

    Berg, J. E. Van Den; Meinema, C.; Mathavan, S.; Hoekstra, S.

    2013-06-01

    We have set up up a travelling-wave Stark-decelerator optimised for the deceleration and trapping of heavy diatomic molecules. This decelerator is an important first step in the optimal preparation of heavy diatomic molecules for sensitive studies of fundamental symmetries. The decelerator uses ring-shaped electrodes to create a moving trapping potential, that can be brought to a standstill in the laboratory frame by electronic control. With such a device, a wide range of molecules in the weak-field seeking part of excited rotational states can be decelerated and trapped. We demonstrate the working principle of our method using SrF molecules, which are well suited to probe for parity violation.

  6. Preparation of a panoscopic mimic diatom from a silicon compound.

    PubMed

    Fei, Bin; Hu, Zhigang; Lu, Haifeng; Xin, John H

    2007-11-01

    Inspired by biological design principles, a panoscopic mimic diatom was created by hierarchical self-assembly of reactive amphiphiles in a multiphase medium comprising hexadecane, ethanol, water, and hydrochloric acid. Through simple stirring at room temperature, mesolamellar macroporous capsules covering oil droplets were obtained in large quantity, which was confirmed by NMR spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetry. At the mesoscale, amphiphilic C(16)Si(OH)(3) assembled into bilayer lamellae through polycondensation, hydrophobic interaction, and H bonding. At the micrometer scale, the bilayer lamellae nucleated at the interface and grew into a polar phase, thus leading to delicate microcages or mimic diatoms. Moreover, the microcages tended to interconnect and fuse into a continuous coating at the centimeter scale, which provided hydrophobicity through the micropatterned surface. This paradigm for creating hierarchical materials with multiphases could lead to new "synthetic" material technologies and novel fascinating materials with anisotropic properties. PMID:17935065

  7. Accumulation of (241)Am by suspended matter, diatoms and aquatic weeds of the Yenisei River.

    PubMed

    Zotina, T A; Bolsunovsky, A Ya; Bondareva, L G

    2010-02-01

    In this work we experimentally estimated the capacities of the key components of the Yenisei River (Russia): particulate suspended matter (seston), diatom microalgae, and submerged macrophytes for accumulating (241)Am from water. In our experiments large particles of seston (>8mum), comparable in size with diatoms, took up most of americium from water. The accumulation of americium by isolated diatom algae (Asterionella formosa and Diatoma vulgare) was lower than by total seston. The concentration factors (CFs) of (241)Am for seston of the Yenisei River in our experiments were (2.8-6.9).10(5); for diatoms - (1.5-4.2).10(4). The CFs for aquatic plant Elodea canadensis were within the same order of magnitude as those for diatoms. Activity concentration and CFs of (241)Am were nearly the same in experiments under dark and light conditions. This is indicative of an energy independent mechanism of americium uptake from the water by diatoms and submerged macrophytes. PMID:19879676

  8. The distribution and abundance of planktonic diatoms in Lake Superior

    USGS Publications Warehouse

    Holland, Ruth E.

    1965-01-01

    The principal diatoms collected at 14 stations in Lake Superior were Cyclotella "glomerata-stelligera" [= C. glomerata and C. stelligera combined], Cyclotella "ocellata-kutzingiana", Fragilaria crotonensis, and Rhizosolenia eriensis. Concentrations were heaviest in the Apostle Islands region (up to 2,160 per ml) and lightest northwest of the Keweenaw Peninsula (68 to 78 per ml). Species composition differed in different parts of the lake.

  9. Reinvestigation of rotational-line intensity factors in diatomic spectra

    NASA Technical Reports Server (NTRS)

    Whiting, E. E.; Nicholls, R. W.

    1974-01-01

    The theory of the intensity factors of rotational lines in diatomic molecular spectra is reviewed with an emphasis on removing obscurities and resolving ambiguities that exist. For example, a unified intensity-factor sum rule is derived that is valid for all spin-allowed and spin-forbidden dipole transitions. Further, it is shown that the electronic transition moments can always be chosen to be real and that a few simple rules ensure the application of consistent phase factors.

  10. Structure of a diatomic fluid near a wall

    Microsoft Academic Search

    S. M. Thompson; K. E. Gubbins; D. E. Sullivan; C. G. Gray

    1984-01-01

    Molecular dynamics has been used to simulate a high density fluid of homonuclear diatomic molecules in the presence of a rigid planar wall. The molecular interactions were modelled by Lennard-Jones (12, 6) site-site potentials and (17, 3) wall-site potentials. The relative influence of attractive and repulsive forces on the interfacial orientational structure was studied by comparing with simulations in which

  11. Biogenic Silica Structure Formation in Diatoms: Cellular Components and Control

    NASA Astrophysics Data System (ADS)

    Hildebrand, M.

    2006-12-01

    Diatoms are largely responsible on the global scale for biogenic silica formation, and are key components of oceanic silicon cycling. Silicification processes are controlled at the cellular level. Our research is aimed at understanding the molecular basis of silica cell wall formation in diatoms, using molecular, genomic, transgenic, and imaging approaches. Specifically we are 1) examining silicic acid transport into the cell, 2) studying silica structure formation, and 3) identifying and characterizing genes and proteins involved in cell wall formation. Recent work characterizing silicon transporters (SITs) showed that control over transport occurs at multiple levels, depending on intra- and extra-cellular conditions. Comparative sequence analysis of the SITs identified conserved amino acids that may be directly involved in transport, and a mechanistic model for transport has been proposed. Examination of the structure formation process in Thalassiosira pseudonana has identified specific stages, indicative of a "spatial cementing" approach, in which the structure is initially outlined in a thin silica layer, and subsequently thickened and made rigid. Distinct silica morphologies are also formed at different stages, resulting in a material optimized in both its formation and final structural properties. The development of a controlled synchronous growth procedure has enabled the identification of a specific pattern of gene expression indicative of involvement in cell wall synthesis. Using this pattern as a diagnostic, we applied a whole genome microarray approach to identify genes possibly involved in cell wall synthesis. Ongoing characterization of these genes includes determining the intracellular location of the proteins they encode. Sophisticated imaging techniques are also being applied to visualize the process of silicification. Application of these multi-level approaches enable the correlation of molecular and macro-level events involved in diatom silicified cell wall synthesis, leading to a clearer understanding of diatom biosilicification.

  12. Electric Dipole Moments of Rare-Gas Diatomic Molecules

    Microsoft Academic Search

    R. L. Matcha; R. K. Nesbet

    1967-01-01

    Electric dipole moment and interatomic potential functions are computed for the diatomic systems HeNe, HeAr, and NeAr, in the molecular Hartree-Fock approximation. Since this approximation does not include a description of dispersion forces, the potential curves are purely repulsive. The potential and moment functions can all be fitted closely by simple exponential functions over the range of internuclear distances considered,

  13. Germanium incorporation into the silica of diatom cell walls

    Microsoft Academic Search

    Farooq Azam; Barbara B. Hemmingsen; Benjamin E. Volcani

    1973-01-01

    1.The diatoms, Nitzschia alba, Navicula pelliculosa, Cylindrotheca fusiformis, and Cyclotella nana, took up radioisotopically labelled germanic acid, 68Ge(OH)4, from their growth media and incorporated up to 80% of it into the silica of their cell walls. Silicification appeared to be required for germanium incorporation.2.The uptake and incorporation of germanic acid was dependent upon the relative concentrations of Ge(OH)4 and Si(OH)4,

  14. Multiphase laminates of extremal effective conductivity in two dimensions

    NASA Astrophysics Data System (ADS)

    Albin, Nathan; Cherkaev, Andrej; Nesi, Vincenzo

    2007-07-01

    This paper deals with two-dimensional composites made of several isotropic linearly conducting phases in prescribed volume fractions. The primary focus is on the three-phase case; the generalization to a larger number of phases is straightforward. A class of high- but finite-rank laminates is introduced. The laminates saturate the known inequality boundsdue to the work of Hashin and Shtrikman, Lurie and Cherkaev, Tartar, and Murat and Tartaron the effective conductivity tensor of any composite. These bounds depend only on the constituent material properties and volume fractions and not on the placement of these materials in the composite. The bounds are known not to be optimal for all admissible choices of the conductivities and volume fractions. However, they are now known to be realizable in a much larger range of these parameters than was previously known. The range of effective properties of our multiphase laminates strictly includes those corresponding to the composites found earlier by Milton and Kohn, Lurie and Cherkaev, and Gibiansky and Sigmund. The new optimal laminates are found in a systematic fashion by satisfying sufficient conditions on the fields in each layer. This leads to a simple algorithm for generating optimal laminates. In addition a new supplementary bound for multiphase structures is also proven which must be satisfied by composites with smooth interfaces.

  15. Analytical study for deformability of laminated sheet metal

    PubMed Central

    Serror, Mohammed H.

    2012-01-01

    While a freestanding high-strength sheet metal subject to tension will rupture at a small strain, it is anticipated that lamination with a ductile sheet metal will retard this instability to an extent that depends on the relative thickness, the relative stiffness, and the hardening exponent of the ductile sheet. This paper presents an analytical study for the deformability of such laminate within the context of necking instability. Laminates of high-strength sheet metal and ductile low-strength sheet metal are studied assuming: (1) sheets are fully bonded; and (2) metals obey the power law material model. The effect of hardening exponent, volume fraction and relative stiffness of the ductile component has been studied. In addition, stability of both uniform and nonuniform deformations has been investigated under plane strain condition. The results have shown the retardation of the high-strength layer instability by lamination with the ductile layer. This has been achieved through controlling the aforementioned key parameters of the ductile component, while the laminate exhibits marked enhancement in strengthductility combination that is essential for metal forming applications. PMID:25685405

  16. Dynamic Stability of Uncertain Laminated Beams Under Subtangential Loads

    NASA Technical Reports Server (NTRS)

    Goyal, Vijay K.; Kapania, Rakesh K.; Adelman, Howard (Technical Monitor); Horta, Lucas (Technical Monitor)

    2002-01-01

    Because of the inherent complexity of fiber-reinforced laminated composites, it can be challenging to manufacture composite structures according to their exact design specifications, resulting in unwanted material and geometric uncertainties. In this research, we focus on the deterministic and probabilistic stability analysis of laminated structures subject to subtangential loading, a combination of conservative and nonconservative tangential loads, using the dynamic criterion. Thus a shear-deformable laminated beam element, including warping effects, is derived to study the deterministic and probabilistic response of laminated beams. This twenty-one degrees of freedom element can be used for solving both static and dynamic problems. In the first-order shear deformable model used here we have employed a more accurate method to obtain the transverse shear correction factor. The dynamic version of the principle of virtual work for laminated composites is expressed in its nondimensional form and the element tangent stiffness and mass matrices are obtained using analytical integration The stability is studied by giving the structure a small disturbance about an equilibrium configuration, and observing if the resulting response remains small. In order to study the dynamic behavior by including uncertainties into the problem, three models were developed: Exact Monte Carlo Simulation, Sensitivity Based Monte Carlo Simulation, and Probabilistic FEA. These methods were integrated into the developed finite element analysis. Also, perturbation and sensitivity analysis have been used to study nonconservative problems, as well as to study the stability analysis, using the dynamic criterion.

  17. Analytical study for deformability of laminated sheet metal.

    PubMed

    Serror, Mohammed H

    2013-01-01

    While a freestanding high-strength sheet metal subject to tension will rupture at a small strain, it is anticipated that lamination with a ductile sheet metal will retard this instability to an extent that depends on the relative thickness, the relative stiffness, and the hardening exponent of the ductile sheet. This paper presents an analytical study for the deformability of such laminate within the context of necking instability. Laminates of high-strength sheet metal and ductile low-strength sheet metal are studied assuming: (1) sheets are fully bonded; and (2) metals obey the power law material model. The effect of hardening exponent, volume fraction and relative stiffness of the ductile component has been studied. In addition, stability of both uniform and nonuniform deformations has been investigated under plane strain condition. The results have shown the retardation of the high-strength layer instability by lamination with the ductile layer. This has been achieved through controlling the aforementioned key parameters of the ductile component, while the laminate exhibits marked enhancement in strength-ductility combination that is essential for metal forming applications. PMID:25685405

  18. Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.; Smeltzer, Stanley S., III

    2000-01-01

    A study of the attenuation of bending boundary layers in balanced and unbalanced, symmetrically and unsymmetrically laminated cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize the effects of laminate orthotropy and anisotropy on the bending boundary-layer decay length in a very general manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all laminates considered, the results show that the differences between results obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that, in some cases, neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and, in other cases, results in an overestimation.

  19. Leukocyte emigration in the early stages of laminitis.

    PubMed

    Black, Samuel J; Lunn, D Paul; Yin, Cailing; Hwang, Misako; Lenz, Stephen D; Belknap, James K

    2006-01-15

    The mechanisms that initiate the pathophysiologic changes in the digital laminae in equine laminitis are poorly understood. Due to the fact that (1) the horse at risk of laminitis has many similarities clinically to the human sepsis patient and (2) our recent finding of marked laminar proinflammatory cytokine expression at the developmental time point of the black walnut extract (BWE) model of laminitis, we tested the possibility that, similar to organ damage in human sepsis, leukocyte emigration is an early event in laminitis. Using immunoperoxidase methods with an anti-equine CD13 monoclonal antibody that recognizes neutrophils and monocytes, we discovered that, whereas the dermal microvasculature of the skin commonly has a marginal pool of leukocytes, the normal laminar dermal microvasculature has minimal to no perivascular leukocytes. However, increases in leukocyte numbers occurred around the dermal vasculature of both the laminae and the skin in the majority of BWE-treated horses in the developmental stage and at the onset of clinical signs of lameness in the BWE model. These findings indicate that, similar to organ failure in human sepsis, leukocyte emigration is likely to play a significant role in initiating numerous pathophysiologic mechanisms that lead to the development of laminitis. PMID:16169600

  20. Fracture behavior of unidirectional boron/aluminum composite laminates

    NASA Technical Reports Server (NTRS)

    Goree, J. G.; Jones, W. F.

    1983-01-01

    An experiment was conducted to verify the results of mathematical models which predict the stresses and displacements of fibers and the amount of damage growth in a center-notched lamina as a function of the applied remote stress and the matrix and fiber material properties. A brittle lacquer coating was used to detect the yielding in the matrix while X-ray techniques were used to determine the number of broken fibers in the laminate. The notched strengths and the amounts of damage found in the specimens agree well with those predicted by the mathematical model. It is shown that the amount of damage and the crack opening displacement does not depend strongly on the number of plies in the laminate for a given notch width. By heat-treating certain laminates to increase the yield stress of the alumina matrix, the effect of different matrix properties on the fracture behavior was investigated. The stronger matrix is shown to weaken the notched laminate by decreasing the amount of matrix damage, thereby making the laminate more notch sensitive.

  1. Photosystem II photoinactivation, repair, and protection in marine centric diatoms.

    PubMed

    Wu, Hongyan; Roy, Suzanne; Alami, Meriem; Green, Beverley R; Campbell, Douglas A

    2012-09-01

    Diatoms are important contributors to aquatic primary production, and can dominate phytoplankton communities under variable light regimes. We grew two marine diatoms, the small Thalassiosira pseudonana and the large Coscinodiscus radiatus, across a range of temperatures and treated them with a light challenge to understand their exploitation of variable light environments. In the smaller T. pseudonana, photosystem II (PSII) photoinactivation outran the clearance of PSII protein subunits, particularly in cells grown at sub- or supraoptimal temperatures. In turn the absorption cross section serving PSII photochemistry was down-regulated in T. pseudonana through induction of a sustained phase of nonphotochemical quenching that relaxed only slowly over 30 min of subsequent low-light incubation. In contrast, in the larger diatom C. radiatus, PSII subunit turnover was sufficient to counteract a lower intrinsic susceptibility to photoinactivation, and C. radiatus thus did not need to induce sustained nonphotochemical quenching under the high-light treatment. T. pseudonana thus incurs an opportunity cost of sustained photosynthetic down-regulation after the end of an upward light shift, whereas the larger C. radiatus can maintain a balanced PSII repair cycle under comparable conditions. PMID:22829321

  2. Diatoms in late Quaternary sediment from the Orca Basin

    SciTech Connect

    Klas, M.; Burckle, L.H.

    1985-01-01

    Diatoms and clays were studied in core EN32-PC6 from the Orca Basin. This core contains oxygen isotope evidence for increased melt-water outflow from the Mississippi River during the post-Wisconsin deglaciation. Diatoms are present in two intervals: the period of increased melt-water outflow at about 15,000 to 12,000 years BP and during the past 5000 years. The earlier interval (the melt-water spike) contains fresh and brackish water diatoms and open ocean forms that prefer lower salinities while the youngest interval is characterized by open ocean forms. The melt-water spike interval also contains fewer reworked Cretaceous and Paleogene coccoliths and has little or no quartz. A decrease in smectite in the core at about 22,000 years BP may be related to a similar decrease in the Morton loess due to the blocking and diversion of the ancient Mississippi by the advancing Woodfordian glacier of the Lake Michigan lobe. After this diversion, the Mississippi took its present-day course and continued to take outwash away from the receding glacier. In Orca Basin sediments, this is indicated by an increase in smectite. The interval of the melt-water spike seems to be characterized by increased rainfall and sheet flooding.

  3. Models of the delayed nonlinear Raman response in diatomic gases

    SciTech Connect

    Palastro, J. P.; Antonsen, T. M. Jr.; Pearson, A. [Institute for Research in Electronics and Applied Physics, University of Maryland College Park, Maryland 20740 (United States)

    2011-07-15

    We examine the delayed response of a diatomic gas to a polarizing laser field with the goal of obtaining computationally efficient methods for use with laser pulse propagation simulations. We demonstrate that for broadband pulses, heavy molecules such as O{sub 2} and N{sub 2}, and typical atmospheric temperatures, the initial delayed response requires only classical physics. The linear kinetic Green's function is derived from the Boltzmann equation and shown to be in excellent agreement with full density-matrix calculations. A straightforward perturbation approach for the fully nonlinear, kinetic impulse response is also presented. With the kinetic theory a reduced fluid model of the diatomic gas' orientation is derived. Transport coefficients are introduced to model the kinetic phase mixing of the delayed response. In addition to computational rapidity, the fluid model provides intuition through the use of familiar macroscopic quantities. Both the kinetic and the fluid descriptions predict a nonlinear steady-state alignment after passage of the laser pulse, which in the fluid model is interpreted as an anisotropic temperature of the diatomic fluid with respect to motion about the polarization axis.

  4. A Late Quaternary diatom record of tropical climatic history from Lake Titicaca (Peru and Bolivia)

    Microsoft Academic Search

    Pedro M Tapia; Sherilyn C Fritz; Paul A Baker; Geoffrey O Seltzer; Robert B Dunbar

    2003-01-01

    A composite high-resolution diatom stratigraphy from three piston cores and one box-core in the deep sub-basin of Lake Titicaca reveals large moisture variations during the past 30 kyr in the Altiplano region. Diatom sequences indicate orbital and millennial-scale variability in water level and salinity. The pelagic freshwater diatom species Cyclotella andina and Cyclotella stelligera dominate Glacial-age sediments, suggesting that the

  5. Concentration independent absolute intensity determinations A new method. [for diatomic molecular spectra

    NASA Technical Reports Server (NTRS)

    Chackerian, C., Jr.

    1986-01-01

    Attention is given to the means for obtaining, independently of any data on molecular concentration, the absolute intensity determinations on the basis of relative line intensity measurements conducted across the vibration-rotation band of a diatomic molecule. This approach is important for the vibrational fundamental bands of diatomic molecules, which cannot be studied by the lifetime method; its application will be especially significant in the case of diatomic radical species whose concentrations can only be indirectly inferred.

  6. Lamination Formation, CO2 Uptake And Environmental Effects On Morphology: Siliceous Stromatolite Formation In A Hot Spring, Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Corsetti, F. A.; Berelson, W.; Spear, J. R.; Hammond, D. E.; Pepe-Ranney, C.; Beaumont, W.

    2010-12-01

    Siliceous stromatolites were collected from a hot spring in Yellowstone National Park in order to investigate stromatolite morphogenesis and growth rate. The majority of the stromatolite is composed of relatively porous light and dark layers of silica-coated filaments. The light layers (~150 ?m) predominantly consist of surface normal filaments and the dark layers (~50 ?m) are composed of reclining filaments. The main body lamination is interrupted by another style that drapes the entire structure, contains coccoidal as well as filamentous microbial forms, is well-cemented with silica, and includes a significant population of pennate diatoms. Over the course of stromatolite growth, the main body style and the drape style lamination alternated, but the majority of the growth is composed of the light/dark couplets. Radiometric dating (228Th/228Ra, 228Ra/226Ra, and 137Cs) indicate that the growth of a 5 cm stromatolite occurred on the order of years (not tens or hundreds of years), and in situ growth experiments reveal that the light/dark laminae couples do not represent daily, weekly or seasonal cycles. 14C analysis reveals that organic matter from the main body consistently contains lower ?14C versus the drape fabric. As CO2 from the hydrothermal vent waters is radio-carbon dead (which would result in lower ?14C values), we interpret the main body to have formed when spring level was deeper or flowing more vigorously, resulting in a greater influence from spring derived CO2 during photosynthetic CO2 uptake, and the drape to have formed when spring level was shallower or less vigorous, resulting in a greater incorporation of atmospheric CO2. More vigorous flow is likely to also affect the spring temperature. Combining the radiometric age dating, in situ growth experiments, and ?14C analysis suggests that growth of the light/dark couplets is sporadic and linked to rising water levels, whereas formation of the drape style lamination represents falling water levels and possible emergence. It is possible that the changing water levels, and thus stromatolite growth rate and morphology, record the larger scale geologic processes in Yellowstone National Park.

  7. Vibration suppression of laminated composite plates using embedded smart material layers

    E-print Network

    Krishnan, Sivasubramaniam

    2000-01-01

    In this study, a complete theoretical formulation of laminated composite plates with integrated smart material layers that serve as sensors and/or actuators is presented for the vibration suppression of laminated composite plates. The third...

  8. 40 CFR 426.70 - Applicability; description of the automotive glass laminating subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Applicability; description of the automotive glass laminating subcategory. 426.70 Section...CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GLASS MANUFACTURING POINT SOURCE CATEGORY Automotive Glass Laminating Subcategory 426.70...

  9. 40 CFR 426.70 - Applicability; description of the automotive glass laminating subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Applicability; description of the automotive glass laminating subcategory. 426.70 Section...EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) GLASS MANUFACTURING POINT SOURCE CATEGORY Automotive Glass Laminating Subcategory 426.70...

  10. 40 CFR 426.70 - Applicability; description of the automotive glass laminating subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Applicability; description of the automotive glass laminating subcategory. 426.70 Section...CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GLASS MANUFACTURING POINT SOURCE CATEGORY Automotive Glass Laminating Subcategory 426.70...

  11. 40 CFR 426.70 - Applicability; description of the automotive glass laminating subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Applicability; description of the automotive glass laminating subcategory. 426.70 Section...EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) GLASS MANUFACTURING POINT SOURCE CATEGORY Automotive Glass Laminating Subcategory 426.70...

  12. 40 CFR 426.70 - Applicability; description of the automotive glass laminating subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Applicability; description of the automotive glass laminating subcategory. 426.70 Section...EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) GLASS MANUFACTURING POINT SOURCE CATEGORY Automotive Glass Laminating Subcategory 426.70...

  13. The effect of temperature on the bending of laminated glass beams

    E-print Network

    Edel, Matthew Thomas

    1997-01-01

    these advantages are generally accepted, the performance of laminated glass is highly disputed. Of particular interest are the performance of laminated glass at various temperatures and its response to loading over a duration of time. There are two primary...

  14. Plug repairs of marine glass fiber / vinyl ester laminates subjected to uniaxial tension

    E-print Network

    Michelis, Alexandros

    2009-01-01

    Glass fiber/vinyl ester composite laminates are currently being used and proposed for the hulls, bulkheads, and superstructures of large ships. This thesis examines the effectiveness of the repair of such laminates using ...

  15. Role of delamination and interlaminar fatigue in the failure of laminates with ply dropoffs

    E-print Network

    Shim, Dong Jin, 1972-

    2002-01-01

    Analytical and experimental investigations were conducted on laminates with ply dropoffs to better understand the interlaminar stress field and delamination/damage characteristics in such laminates, as well as the relationship ...

  16. Stiffness reduction and stress transfer in composite laminates with transverse matrix cracks

    E-print Network

    Praveen, Grama Narasimhaprasad

    1994-01-01

    Cross-ply laminates and angle-ply laminates with transverse plies containing through-width matrix cracks across the thickness of the transverse plies are studied using a variational, strain energy based approach, complementary to that of Hashin...

  17. Statistical control and experimental design for edge bead reduction in laminating process

    E-print Network

    Fan, Huangjia (Francis Huangjia)

    2010-01-01

    Edge bead formation is a well-known phenomenon typically happening in the lamination due to the physics of this process. It causes the defect of high edge observed in the carton roll after the laminated carton sheets are ...

  18. A mathematical model for the stressed state analysis of cylindrical laminated-composite pressure vessels

    NASA Astrophysics Data System (ADS)

    Bak, Roman; Matyja, Tomasz

    An algorithm and a computer program have been developed for calculating the strength of pressure vessels made of laminated composites. Numerical results for pressure vessels of Kevlar 49 laminates are compared with experimental data in the literature.

  19. Response of grooved composite laminates to out-of-plane contact loading via numerical models

    E-print Network

    Iqbal, Jaffar S

    2011-01-01

    The response of grooved composite laminates to out-of-plane contact loading is examined using numerical modeling through the consideration of contact pressure and stresses within the laminate, with particular focus on the ...

  20. How-to-Do-It: Diatoms: The Ignored Alga in High School Biology.

    ERIC Educational Resources Information Center

    Hungerford, James J.

    1988-01-01

    Provides historical background, descriptions, uses and basis for identification of diatoms. Explains collection, dry-mount cleaning, and preparation procedures of the algae. Cites additional resources. (RT)

  1. Hierarchical and size dependent mechanical properties of silica and silicon nanostructures inspired by diatom algae

    E-print Network

    Garca, Andre Phillip

    2010-01-01

    Biology implements fundamental principles that allow for attractive mechanical properties, as observed in biomineralized structures. For example, diatom algae contain nanoporous hierarchical silicified shells that provide ...

  2. Bacteria and diatom co-occurrence patterns in microbial mats from polar desert streams.

    PubMed

    Stanish, Lee F; O'Neill, Sean P; Gonzalez, Antonio; Legg, Teresa M; Knelman, Joseph; McKnight, Diane M; Spaulding, Sarah; Nemergut, Diana R

    2013-04-01

    The ephemeral stream habitats of the McMurdo Dry Valleys of Antarctica support desiccation and freeze-tolerant microbial mats that are hot spots of primary productivity in an otherwise inhospitable environment. The ecological processes that structure bacterial communities in this harsh environment are not known; however, insights from diatom community ecology may prove to be informative. We examined the relationships between diatoms and bacteria at the community and taxon levels. The diversity and community structure of stream microbial mats were characterized using high-throughput pyrosequencing for bacteria and morphological identification for diatoms. We found significant relationships between diatom communities and the communities of cyanobacteria and heterotrophic bacteria, and co-occurrence analysis identified numerous correlations between the relative abundances of individual diatom and bacterial taxa, which may result from species interactions. Additionally, the strength of correlations between heterotrophic bacteria and diatoms varied along a hydrologic gradient, indicating that flow regime may influence the overall community structure. Phylogenetic consistency in the co-occurrence patterns suggests that the associations are ecologically relevant. Despite these community- and taxon-level relationships, diatom and bacterial alpha diversity were inversely correlated, which may highlight a fundamental difference between the processes that influence bacterial and diatom community assembly in these streams. Our results therefore demonstrate that the relationships between diatoms and bacteria are complex and may result from species interactions as well as niche-specific processes. PMID:22998505

  3. Author's personal copy A time-calibrated multi-gene phylogeny of the diatom genus Pinnularia

    E-print Network

    Wolfe, Alexander P.

    ., 1990) and a diplontic life cycle involving gradual size reduc- tion during vegetative divisions. Introduction Diatoms are an extremely diverse group of unicellular algae that are uniquely characterized

  4. Grazing-induced changes in cell wall silicification in a marine diatom.

    PubMed

    Pondaven, Philippe; Gallinari, Morgane; Chollet, Sophie; Bucciarelli, Eva; Sarthou, Graldine; Schultes, Sabine; Jean, Frdric

    2007-01-01

    In aquatic environments, diatoms (Bacillariophyceae) constitute a central group of microalgae which contribute to about 40% of the oceanic primary production. Diatoms have an absolute requirement for silicon to build-up their silicified cell wall in the form of two shells (the frustule). To date, changes in diatom cell wall silicification have been only studied in response to changes in the growth environment, with consistent increase in diatom silica content when specific growth rates decrease under nutrient or light limitations. Here, we report the first evidence for grazing-induced changes in cell wall silicification in a marine diatom. Cells grown in preconditioned media that had contained both diatoms and herbivores are significantly more silicified than diatoms grown in media that have contained diatoms alone or starved herbivores. These observations suggest that grazing-induced increase in cell wall silicification can be viewed as an adaptive reaction in habitats with variable grazing pressure, and demonstrate that silicification in diatoms is not only a constitutive mechanical protection for the cell, but also a phenotypically plastic trait modulated by grazing. In turn, our results corroborate the idea that plant-herbivore interactions, beyond grazing sensu stricto, contribute to drive ecosystem structure and biogeochemical cycles in the ocean. PMID:17081802

  5. Environmental factors controlling lake diatom communities: a meta-analysis of published data

    NASA Astrophysics Data System (ADS)

    Blanco, S.

    2014-11-01

    Diatoms play a key role in the development of quantitative methods for environmental reconstruction in lake ecosystems. Diatom-based calibration datasets developed during the last decades allow the inference of past limnological variables such as TP, pH or conductivity and provide information on the autecology and distribution of diatom taxa. However, little is known about the relationships between diatoms and climatic or geographic factors. The response of surface sediment diatom assemblages to abiotic factors is usually examined using canonical correspondence analysis (CCA) and subsequent forward selection of variables based on Monte Carlo permutation tests that show the set of predictors best explaining the distributions of diatom species. The results reported in 40 previous studies using this methodology in different regions of the world are re-analyzed in this paper. Bi- and multivariate statistics (canonical correlation and two-block partial least-squares) were used to explore the correspondence between physical, chemical and physiographical factors and the variables that explain most of the variance in the diatom datasets. Results show that diatom communities respond mainly to chemical variables (pH, nutrients) with lake depth being the most important physiographical factor. However, the relative importance of certain parameters varied along latitudinal and trophic gradients. Canonical analyses demonstrated a strong concordance with regard to the predictor variables and the amount of variance they captured, suggesting that, on a broad scale, lake diatoms give a robust indication of past and present environmental conditions.

  6. Thermal modeling of carbon-epoxy laminates in fire environments.

    SciTech Connect

    McGurn, Matthew T. (University at Buffalo, the State University of New York (SUNY Buffalo), Buffalo, NY); DesJardin, Paul Edward (University at Buffalo, the State University of New York (SUNY Buffalo), Buffalo, NY); Dodd, Amanda B.

    2010-10-01

    A thermal model is developed for the response of carbon-epoxy composite laminates in fire environments. The model is based on a porous media description that includes the effects of gas transport within the laminate along with swelling. Model comparisons are conducted against the data from Quintere et al. Simulations are conducted for both coupon level and intermediate scale one-sided heating tests. Comparisons of the heat release rate (HRR) as well as the final products (mass fractions, volume percentages, porosity, etc.) are conducted. Overall, the agreement between available the data and model is excellent considering the simplified approximations to account for flame heat flux. A sensitivity study using a newly developed swelling model shows the importance of accounting for laminate expansion for the prediction of burnout. Excellent agreement is observed between the model and data of the final product composition that includes porosity, mass fractions and volume expansion ratio.

  7. Laminations and microgranule formation in pediatric glomerular basement membranes.

    PubMed

    Craver, Randall; Crespo-Salgado, Janice; Aviles, Diego

    2014-01-01

    Glomerular basement membrane (GBM) splitting, laminations, and microgranular formation are classically encountered with Alport disease, but can be found in other glomerular diseases. We found moderate to marked GBM laminations/microgranular formations in 51 of 724 (7%) pediatric diagnostic renal biopsies. These included 12 Alport disease, 12 thin basement membrane disease (TBM), 13 mesangial hypercellularity (MH), 6 focal segmental glomerulosclerosis (FSGS), and 8 other diseases. Follow-up demonstrated progression in most of the Alport disease and FSGS, as expected, but also in 40% of TBM and 30% of MH. Basement membrane laminations/microgranular formations are not specific for Alport disease, may represent a non-specific injury, and may herald a progressive clinical course. PMID:25394298

  8. Low-temperature mechanical properties of glass/epoxy laminates

    SciTech Connect

    Reed, R. P. [Cryogenic Materials, Inc., Boulder, CO 80305 (United States); Madhukar, M.; Thaicharoenporn, B. [Magnet Development Laboratory, Knoxville, TN 37996 (United States); Martovetsky, N. N. [US-ITER Project, Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States)

    2014-01-27

    Selected mechanical properties of glass/epoxy laminate candidates for use in the electrical turn and ground insulation of the ITER Central solenoid (CS) modules were measured. Short-beam shear and flexural tests have been conducted on various E-glass cloth weaves/epoxy laminates at 295 and 77 K. Types of glass weave include 1581, 7500, 7781, and 38050, which represent both satin and plain weaves. The epoxy, planned for use for vacuum-pressure impregnation of the CS module, consists of an anhydride-cured bisphenol F resin system. Inter-laminar shear strength, flexural elastic modulus, and flexural strength have been measured. The data indicate that these properties are dependent on the volume percent of glass. Short-beam shear strength was measured as a function of the span-to-thickness ratio for all laminates at 77 K. Comprehensive fractography was conducted to obtain the failure mode of each short-beam shear test sample.

  9. Snap-Through of Unsymmetric Laminates Using Piezocomposite Actuators

    NASA Technical Reports Server (NTRS)

    Schultz, Marc R.; Hyer, Michael W.; Williams, R. Brett; Wilkie, W. Keats; Inman, Daniel J.

    2006-01-01

    The paper discusses the concept of using a piezoceramic actuator bonded to one side of a two-layer unsymmetric cross-ply [0/90]T laminate to provide the moments necessary to snap the laminate from one stable equilibrium shape to another. This concept could be applied to the morphing of structures. A model of this concept, which is based on the Rayleigh-Ritz technique and the use of energy and variational methods, is developed. The experimental phase of the study is discussed, including the measurement of the voltage level needed to snap the laminate. The voltage measurements and shapes are compared with predictions of the models and the agreement between measurements and the predictions are reasonable, both qualitatively and quantitatively. Suggestions for future activities are presented.

  10. Analysis of stiffness loss in cross-ply composite laminates

    NASA Astrophysics Data System (ADS)

    Tay, T. E.; Lim, E. H.

    A constitutive model of the damage state for composite laminates, first proposed by Allen et al. (1987), is used with a damage evolution criterion based on strain energy to predict the stiffness loss due to matrix cracking in cross-ply laminated composite plates. Although the constitutive model does not require the determination of many constants, the state of damage is described by a vector of internal state variables (ISVs), which contains information on the crack geometry and fracture modes. The effects of relative ply thicknesses, crack density, and crack opening profile on the vector of ISVs are determined. The analysis results compare favorably with experimental measurements of progressive stiffness loss in damaged cross-ply graphite-epoxy laminates obtained from other studies.

  11. A comparison of simple shear characterization methods for composite laminates

    NASA Technical Reports Server (NTRS)

    Yeow, Y. T.; Brinson, H. F.

    1977-01-01

    Various methods for the shear stress-strain characterization of composite laminates are examined, and their advantages and limitations are briefly discussed. Experimental results and the necessary accompanying analysis are then presented and compared for three simple shear characterization procedures. These are the off-axis tensile test method, the + or - 45 degs tensile test method and the 0 deg/90 degs symmetric rail shear test method. It is shown that the first technique indicates that the shear properties of the G/E laminates investigated are fundamentally brittle in nature while the latter two methods tend to indicate that the G/E laminates are fundamentally ductile in nature. Finally, predictions of incrementally determined tensile stress-strain curves utilizing the various different shear behavior methods as input information are presented and discussed.

  12. Nonlinear response of resin matrix laminates using endochronic theory

    NASA Technical Reports Server (NTRS)

    Mathison, S. R.; Pindera, M. J.; Herakovich, C. T.

    1991-01-01

    The nonlinear response of laminated, resin matrix fibrous composites is modeled using orthotropic endochronic theory. The theory is formulated in terms of elastic constants and endochronic parameters characterizing the linear and nonlinear response, respectively, of unidirectional composites. All constants and parameters can be determined from normal (tension and/or compression) and shear tests on unidirectional and off-axis specimens. The nonlinear constitutive response relations for the unidirectional lamina are presented and the procedure for determining constants and parameters from test is described. The results are then used to predict the nonlinear response of unidirectional laminae and angle-ply laminates. Comparison between theory and experiment for compression loading of AS4/3502 graphite-epoxy, angle-ply laminates shows excellent correlation.

  13. Elastic Buckling of Laminated Plates Under Varying Axial Stresses

    NASA Technical Reports Server (NTRS)

    Badir, A.; Hu, H.

    1998-01-01

    The elastic buckling load of simply supported rectangular composite plates subjected to a second degree parabolic variation of axial stresses in the longitudinal direction is calculated using analytical methods. The variation of axial stresses is equilibrated by nonuniform shear stresses along the plate edges and transverse normal stresses. Numerical results are reported for three different cases: (1) orthotropic plates, (2) symmetrically laminated plates with multiple generally orthotropic layers exhibiting coupling between normal moments and twist, and twisting moment and normal curvatures, and (3) unsymmetrically laminated plates. Rayleigh-Ritz method is used to calculate the buckling load. An approximate solution using "reduced bending stiffness" is adopted for unsymmetrically laminated plates. The influence of the aspect ratio is examined, and the results are compared with plates subjected to uniform axial stresses.

  14. Hybrid Titanium Composite Laminates: A New Aerospace Material

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Cobb, Ted Q.; Lowther, Sharon; St.Clair, T. L.

    1998-01-01

    In the realm of aerospace design and performance, there are few boundaries in the never-ending drive for increased performance. This thirst for ever-increased performance of aerospace equipment has driven the aerospace and defense industries into developing exotic, extremely high-performance composites that are pushing the envelope in terms of strength-to-weight ratios, durability, and several other key measurements. To meet this challenge of ever-increasing improvement, engineers and scientists at NASA-Langley Research Center (NASA-LaRC) have developed a high-temperature metal laminate based upon titanium, carbon fibers, and a thermoplastic resin. This composite, known as the Hybrid Titanium Composite Laminate, or HTCL, is the latest chapter in a significant, but relatively short, history of metal laminates.

  15. Damage prediction in cross-plied curved composite laminates

    NASA Technical Reports Server (NTRS)

    Martin, Roderick H.; Jackson, Wade C.

    1991-01-01

    Analytical and experimental work is detailed which is required to predict delamination onset and growth in a curved cross plied composite laminate subjected to static and fatigue loads. The composite used was AS4/3501/6, graphite/epoxy. Analytically, a closed form stress analysis and 2-D and 3-D finite element analyses were conducted to determine the stress distribution in an undamaged curved laminate. The finite element analysis was also used to determine values of strain energy release rate at a delamination emanating from a matrix crack in a 90 deg ply. Experimentally, transverse tensile strength and fatigue life were determined from flat 90 deg coupons. The interlaminar tensile strength and fatigue life were determined from double cantilevered beam specimens. Cross plied curved laminates were tested statically and in fatigue to give a comparison to the analytical predictions. A comparison of the fracture mechanics life prediction technique and the strength based prediction technique is given.

  16. Low-temperature mechanical properties of glass/epoxy laminates

    NASA Astrophysics Data System (ADS)

    Reed, R. P.; Madhukar, M.; Thaicharoenporn, B.; Martovetsky, N. N.

    2014-01-01

    Selected mechanical properties of glass/epoxy laminate candidates for use in the electrical turn and ground insulation of the ITER Central solenoid (CS) modules were measured. Short-beam shear and flexural tests have been conducted on various E-glass cloth weaves/epoxy laminates at 295 and 77 K. Types of glass weave include 1581, 7500, 7781, and 38050, which represent both satin and plain weaves. The epoxy, planned for use for vacuum-pressure impregnation of the CS module, consists of an anhydride-cured bisphenol F resin system. Inter-laminar shear strength, flexural elastic modulus, and flexural strength have been measured. The data indicate that these properties are dependent on the volume percent of glass. Short-beam shear strength was measured as a function of the span-to-thickness ratio for all laminates at 77 K. Comprehensive fractography was conducted to obtain the failure mode of each short-beam shear test sample.

  17. Mechanisms of compressive failure in woven composites and stitched laminates

    NASA Technical Reports Server (NTRS)

    Cox, B. N.; Dadkhah, M. S.; Inman, R. V.; Morris, W. L.; Schroeder, S.

    1992-01-01

    Stitched laminates and angle interlock woven composites have been studied in uniaxial, in-plane, monotonic compression. Failure mechanisms have been found to depend strongly on both the reinforcement architecture and the degree of constraint imposed by the loading grips. Stitched laminates show higher compressive strength, but are brittle, possessing no load bearing capacity beyond the strain for peak load. Post-mortem inspection shows a localized shear band of buckled and broken fibers, which is evidently the product of an unstably propagating kink band. Similar shear bands are found in the woven composites if the constraint of lateral displacements is weak; but, under strong constraint, damage is not localized but distributed throughout the gauge section. While the woven composites tested are weaker than the stitched laminates, they continue to bear significant loads to compressive strains of approx. 15 percent, even when most damage is confined to a shear band.

  18. Biogeochemistry of silica in Devils Lake: Implications for diatom preservation

    USGS Publications Warehouse

    Lent, R.M.; Lyons, B.

    2001-01-01

    Diatom-salinity records from sediment cores have been used to construct climate records of saline-lake basins. In many cases, this has been done without thorough understanding of the preservation potential of the diatoms in the sediments through time. The purpose of this study was to determine the biogeochemistry of silica in Devils Lake and evaluate the potential effects of silica cycling on diatom preservation. During the period of record, 1867-1999, lake levels have fluctuated from 427 m above sea level in 1940 to 441.1 m above sea level in 1999. The biogeochemistry of silica in Devils Lake is dominated by internal cycling. During the early 1990s when lake levels were relatively high, about 94% of the biogenic silica (BSi) produced in Devils Lake was recycled in the water column before burial. About 42% of the BSi that was incorporated in bottom sediments was dissolved and diffused back into the lake, and the remaining 58% was buried. Therefore, the BSi accumulation rate was about 3% of the BSi assimilation rate. Generally, the results obtained from this study are similar to those obtained from studies of the biogeochemistry of silica in large oligotrophic lakes and the open ocean where most of the BSi produced is recycled in surface water. During the mid 1960s when lake levels were relatively low, BSi assimilation and water-column dissolution rates were much higher than when lake levels were high. The BSi assimilation rate was as much as three times higher during low lake levels. Even with the much higher BSi assimilation rate, the BSi accumulation rate was about three times lower because the BSi water-column dissolution rate was more than 99% of the BSi assimilation rate compared to 94% during high lake levels. Variations in the biogeochemistry of silica with lake level have important implications for paleolimnologic studies. Increased BSi water-column dissolution during decreasing lake levels may alter the diatom-salinity record by selectively removing the less resistant diatoms. Also, BSi accumulation may be proportional to the amount of silica input from tributary sources. Therefore, BSi accumulation chronologies from sediment cores may be effective records of tributary inflow.

  19. Loss of A-type Lamin Expression Compromises Nuclear Envelope Integrity Leading to Muscular Dystrophy

    Microsoft Academic Search

    Teresa Sullivan; Diana Escalante-Alcalde; Harshida Bhatt; Miriam Anver; Narayan Bhat; Kunio Nagashima; Colin L. Stewart; Brian Burke

    1999-01-01

    The nuclear lamina is a protein meshwork lining the nucleoplasmic face of the inner nuclear mem- brane and represents an important determinant of in- terphase nuclear architecture. Its major components are the A- and B-type lamins. Whereas B-type lamins are found in all mammalian cells, A-type lamin expres- sion is developmentally regulated. In the mouse, A-type lamins do not appear

  20. Development of laminated fiber-reinforced nanocomposites for bone regeneration

    NASA Astrophysics Data System (ADS)

    Xu, Weijie

    There have been numerous efforts to develop synthetic and/or natural tissue engineering scaffolds that are suitable for bone regeneration applications to replace autograft and allograft bones. Current biomaterials as a scaffold for bone regeneration are limited by the extent of degradation concurrent with bone formation, mechanical strength, and the extent of osteogenic differentiation of marrow stromal cells migrating from the surrounding tissues. In this project, a novel laminated nanocomposite scaffold is fabricated, consisting of poly (L-lactide ethylene oxide fumarate) (PLEOF) hydrogel reinforced with poly (L-lactic acid) (PLLA) electrospun nanofibers and hydroxyapatite (HA) nanoparticles. PLEOF is a novel in situ crosslinkable macromer synthesized from biocompatible building units which can be functionalized with bioactive peptides like the cell-adhesive Arg--Gly--Asp (RGD) amino acid sequence. The hydrophilicity and degradation rate of the macromer can be tailored to a particular application by controlling the ratio of PEG to PLA blocks in the macromer and the unsaturated fumarate units can be used for in-situ crosslinking. The PLLA nanofibers were electrospun from high molecular weight PLLA. The laminated nanocomposites were fabricated by dry-hand lay up technique followed by compression molding and thermal crosslinking. The laminated nanocomposites were evaluated with respect to degradation, water uptake, mechanical strength, and the extent of osteogenic differentiation of bone marrow stromal (BMS) cells. Laminates with or without HA nanoparticles showed modulus values much higher than that of trabecular bone (50-100 MPa). The effect of laminated nanocomposites on osteogenic differentiation of BMS cells was determined in terms of cell number, ALPase activity and calcium content. Our results demonstrate that grafting RGD peptide and HA nanoparticles to a PLEOF hydrogel reinforced with PLLA nanofibers synergistically enhance osteogenic differentiation of BMS cells. In conclusion, the laminated nanocomposite with controllable degradation characteristics and robust mechanical properties is attractive as a synthetic bone-mimetic matrix for skeletal tissue regeneration.

  1. Effect of microstructural damage on ply stresses in laminated composites

    NASA Technical Reports Server (NTRS)

    Allen, D. H.; Nottorf, E. W.; Harris, C. E.

    1988-01-01

    The mechanisms involved in damage and failure of laminated orthotropic composites are investigated theoretically. The continuum model developed accounts for both matrix cracks and interply delamination using second-order tensor-valued internal-state variables based on the locally averaged microcrack dynamics. The derivation of the model is given in detail, and numerical results for sample problems are presented in extensive graphs and tables. The model is shown to be effective in predicting stresses at the ply level, and significant damage-induced decreases in laminate stress states are found.

  2. Plasticity analysis of fibrous composite laminates under thermomechanical loads

    NASA Technical Reports Server (NTRS)

    Bahei-El-din, Yehia A.

    1990-01-01

    Elastic-plastic behavior of fibrous composite laminates is analyzed for coupled in-plane mechanical loads and uniform thermal changes. Constitutive equations of the individual fibrous layers are derived from a vanishing fiber diameter model that represents the essential axial constraint between the phases. This permits derivation of closed form equations for the overall yield condition, stress concentration factors, and instantaneous compliance. Thermoelastic properties of the phases and yield stress of the matrix phase are functions of temperature. The effect of the model assumptions on the predicted behavior of composite laminates is examined by comparing the calculated response under cyclic thermal changes to available theoretical results and experimental measurements.

  3. A matrix damage accumulation model for laminated composites

    E-print Network

    Lo, David Chi Shing

    1990-01-01

    crack damage accumulation in the 90' plies of [0/~~45/90], lami- nates subjected tn fatigue loads. . Figure Page 15 Normalized axial stiffnesses for [0/~45/90], laminates under fatigue load- ing 16 Axial stresses in the 0' plies of [0.... , Texas A8-M University Co-Chairs of Advisory Committee: Dr. D. H. Allen Dr. C. E. Harris A damage evolutionary relationship was developed to model the accuntulation of' intraply matrix cracks in laminated composites. This relationship was formulated...

  4. Laminated rubber articulated joint for the Deep Water Gravity Tower

    SciTech Connect

    Sedillot, F.; Stevenson, A.

    1983-12-01

    The Deep Water Gravity Tower is an articulated structure resting on a fixed base through an articulated joint which is composed of curved laminated rubber pads, made from alternate layers of rubber and metallic shims. The paper first outlines the main design concept with the articulated joint. Some analysis is then provided of the response to imposed rotation and vertical load. This includes a brief description of the results of a finite element analysis. The paper then reviews the test performed on laminated rubber during 1980 and 1981 to assess the feasibility of the articulation: fatigue tests; environmental tests (effect of sea water, temperature, pressure).

  5. Metal Matrix Laminate Tailoring (MMLT) code: User's manual

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Morel, M. R.; Saravanos, D. A.

    1993-01-01

    The User's Manual for the Metal Matrix Laminate Tailoring (MMLT) program is presented. The code is capable of tailoring the fabrication process, constituent characteristics, and laminate parameters (individually or concurrently) for a wide variety of metal matrix composite (MMC) materials, to improve the performance and identify trends or behavior of MMC's under different thermo-mechanical loading conditions. This document is meant to serve as a guide in the use of the MMLT code. Detailed explanations of the composite mechanics and tailoring analysis are beyond the scope of this document, and may be found in the references. MMLT was developed by the Structural Mechanics Branch at NASA Lewis Research Center (LeRC).

  6. Farnesylation of lamin B1 is important for retention of nuclear chromatin during neuronal migration

    PubMed Central

    Jung, Hea-Jin; Nobumori, Chika; Goulbourne, Chris N.; Tu, Yiping; Lee, John M.; Tatar, Angelica; Wu, Daniel; Yoshinaga, Yuko; de Jong, Pieter J.; Coffinier, Catherine; Fong, Loren G.; Young, Stephen G.

    2013-01-01

    The role of protein farnesylation in lamin A biogenesis and the pathogenesis of progeria has been studied in considerable detail, but the importance of farnesylation for the B-type lamins, lamin B1 and lamin B2, has received little attention. Lamins B1 and B2 are expressed in nearly every cell type from the earliest stages of development, and they have been implicated in a variety of functions within the cell nucleus. To assess the importance of protein farnesylation for B-type lamins, we created knock-in mice expressing nonfarnesylated versions of lamin B1 and lamin B2. Mice expressing nonfarnesylated lamin B2 developed normally and were free of disease. In contrast, mice expressing nonfarnesylated lamin B1 died soon after birth, with severe neurodevelopmental defects and striking nuclear abnormalities in neurons. The nuclear lamina in migrating neurons was pulled away from the chromatin so that the chromatin was left naked (free from the nuclear lamina). Thus, farnesylation of lamin B1but not lamin B2is crucial for brain development and for retaining chromatin within the bounds of the nuclear lamina during neuronal migration. PMID:23650370

  7. Analysis of interlaminar stresses in thick composite laminates with and without edge delamination

    NASA Technical Reports Server (NTRS)

    Whitcomb, J. D.; Raju, I. S.

    1984-01-01

    The effect of laminate thickness on the interlaminar stresses in rectangular quasi-isotropic laminates under uniform axial strain was studied. Laminates from 8-ply to infinitely thick were analyzed. Thick laminates were synthesized by stacking (45/0/-45/90) ply groups, rather than grouping like plies. Laminates with and without delaminations were studied. In laminates without delaminations, the free-edge interlaminar normal stress distribution in the outer ply groups was insensitive to total laminate thickness. The interlaminar normal stress distribution for the interior ply groups was nearly the same as for an infinitely thick laminate. In contrast, the free-edge inter-laminar shear stress distribution was nearly the same for inner and outer ply groups and was insensitive to laminate thickness. In laminates with delaminations those delaminations near the top and bottom surfaces of a thick laminate have much larger total strain-energy-release rates (G sub t) and mode I-to-total (G sub t/G sub t) ratios than delaminations deep in the interior. Therefore, delaminations can be expected to grow more easily near the surfaces of a laminate than in the interior.

  8. Evaluation on the suitability of some adhesives for laminated veneer lumber from oil palm trunks

    Microsoft Academic Search

    O. Sulaiman; N. Salim; R. Hashim; L. H. M. Yusof; W. Razak; N. Y. M. Yunus; W. S. Hashim; M. H. Azmy

    2009-01-01

    Laminated veneer lumbers from oil palm trunk were manufactured using urea formaldehyde, phenol formaldehyde, melamine urea formaldehyde, and phenol resorcinol formaldehyde adhesives. The density of the oil palm laminated veneer lumber was slightly higher than the solid oil palm trunk. The thickness swelling and water absorption of laminated veneer lumber of oil palm were higher than those made from rubberwood.

  9. THE MAGNETOELECTRIC EFFECTS OF TERFENOL-D/PZT/TERFENOL-D LAMINATED STRUCTURES

    E-print Network

    Wang, Ji

    163 THE MAGNETOELECTRIC EFFECTS OF TERFENOL-D/PZT/TERFENOL-D LAMINATED STRUCTURES Long XIA, Jian * Corresponding author, E-mail: dujianke@nbu.edu.cn; Tel.: 86-574-87600074. Magnetoelectric (ME) laminated in the magnetostrictive layers and a piezoelectric effect in the piezoelectric layers. Laminated Magnetoelectric material

  10. Interface characterization of nanoscale laminate structures on dense dielectric substrates by x-ray reflectivity

    Microsoft Academic Search

    Y. Travaly; J. Schuhmacher; A. M. Hoyas; M. van Hove; K. Maex; T. Abell; V. Sutcliffe; A. M. Jonas

    2005-01-01

    On nanoscale laminate structures, the interface cannot be identified any longer as the separation between two films of bulk materials. The formation of the interface defines the final composition and structure of the laminate structure. As such, the characterization of the interface becomes an important challenge. In this work the nanoscale laminate structures were formed by atomic layer deposition (ALD)

  11. The effects of kinematic model approximations on natural frequencies and modal damping of laminated composite plates

    Microsoft Academic Search

    M. Soula; R. Nasri; A. Ghazel; Y. Chevalier

    2006-01-01

    The present work deals with the effects of kinematics on the natural frequencies and modal damping of laminated composite plates. Three theories are considered, the classical laminated plate theory (CLPT), the first-order shear deformation theory (FSDT) and the third-order shear deformation theory (TSDT). The displacement field corresponding to a simply supported square laminated composite plate is introduced in the energy

  12. Nuclear lamins and peripheral nuclear antigens during fertilization and embryogenesis in mice and sea urchins

    NASA Technical Reports Server (NTRS)

    Schatten, G.; Schatten, H.; Simerly, C.; Maul, G. G.; Chaly, N.

    1985-01-01

    Nuclear structural changes during fertilization and embryogenesis in mice and sea urchins are traced using four antibodies. The oocytes from virgin female mice, morulae and blastocytes from mated females, and gametes from the sea urchin Lytechnius variegatis are studied using mouse monoclonal antibodies to nuclear lamin A/C, monoclonal antibody to P1, human autoimmune antibodies to lamin A/C, and to lamin B. The mouse fertilization data reveal no lamins on the oocyte; however, lamins are present on the pronuclei, and chromosomes are found on the oocytes and pronuclei. It is detected that on the sea urchin sperm the lamins are reduced to acrosomal and centriolar fossae and peripheral antigens are around the sperm nucleus. The mouse sperm bind lamin antibodies regionally and do not contain antigens. Lamins and antigens are observed on both pronuclei and chromosomes during sea urchin fertilization. Mouse embryogenesis reveals that lamin A/C is not recognized at morula and blastocyst stages; however, lamin B stains are retained. In sea urchin embryogenesis lamin recognition is lost at the blastrula, gastrula, and plutei stages. It is noted that nuclear lamins lost during spermatogenesis are restored at fertilization and peripheral antigens are associated with the surface of chromosomes during meiosis and mitosis and with the periphery of the pronuclei and nuclei during interphase.

  13. Disruption of Nuclear Lamin Organization Blocks the Elongation Phase of DNA Replication

    Microsoft Academic Search

    Robert D. Moir; Timothy P. Spann; Harald Herrmann; Robert D. Goldman

    2000-01-01

    The role of nuclear lamins in DNA replica- tion is unclear. To address this, nuclei were assembled in Xenopus extracts containing AraC, a reversible in- hibitor that blocks near the onset of the elongation phase of replication. Dominant-negative lamin mutants lacking their NH 2 -terminal domains were added to as- sembled nuclei to disrupt lamin organization. This pre- vented the

  14. Analytical Modelling of Transverse Matrix Cracking of {?\\/90} Composite Laminates under Multiaxial Loading

    Microsoft Academic Search

    J. A. Mayugo; P. P. Camanho; P. Maim; C. G. Dvila

    2010-01-01

    An analytical model based on the analysis of a cracked unit cell of a composite laminate subjected to multiaxial loads is proposed to predict the onset and accumulation of transverse matrix cracks in the 90n plies of uniformly stressed {?\\/90} laminates. The model predicts the effect of matrix cracks on the stiffness of the laminate, as well as the ultimate

  15. Analysis and optimization of vertically oriented, through-wafer, laminated magnetic cores in silicon

    Microsoft Academic Search

    David P Arnold; Iulica Zana; Mark G Allen

    2005-01-01

    This paper compares two fabrication methods for achieving through-wafer, laminated magnetic cores in silicon, intended for microfabricated magnetic devices where vertically oriented (normal to the wafer) magnetic laminations are required to reduce eddy current losses. Given certain fabrication constraints for each method, a theoretical framework is presented to permit the design of the optimal lamination scheme for a particular application.

  16. Seasonal and interannual dynamics in diatom production in the Cariaco Basin, Venezuela

    NASA Astrophysics Data System (ADS)

    Romero, Oscar E.; Thunell, Robert C.; Astor, Yrene; Varela, Ramon

    2009-04-01

    We examine the diatom flux collected between November 1996 and April 1998, and between January and October 1999 at the time-series study site in the Cariaco Basin, off Venezuela. The temporal dynamics of the total diatom flux mainly reflect seasonal, trade wind-driven changes in surface hydrographic conditions, including changes associated with the El Nio/Southern Oscillation (ENSO). Highest diatom fluxes (>1.810 7 valves m -2 d -1) coincided with the upwelling season in boreal winters 1997 and 1999. Changes in the composition of the diverse diatom community reflect variations in hydrographic and atmospheric conditions, as well as nutrient availability. Cyclotella litoralis, a neritic diatom typical of nutrient-rich waters, along with resting spores of several Chaetoceros spp., dominate during periods of high diatom flux, following trade wind-driven upwelling. During the boreal summers of 1997 and 1999, nutrient-depleted surface waters resulted in low diatom fluxes (<5.210 6 valves m -2 d -1). The seasonal pattern of high diatom production was altered from July 1997 through April 1998, when the ENSO affected the Caribbean Sea. The occurrence of ENSO during boreal winter 1997-1998 caused a major change in the qualitative composition of the diatom assemblage: the highly diverse diatom assemblage was composed of a mixture of pelagic ( Nitzschia bicapitata, Thalassionema nitzschioides var. inflata, T. nitzschioides var . parva, Azpeitia tabularis) and coastal species ( C. litoralis, resting spores of Chaetoceros, T. nitzschioides var. nitzschioides). The simultaneous occurrence of neritic and open-ocean diatoms during boreal summers reflects the fact that the Cariaco Basin is influenced by both offshore and coastal waters, with considerable short-term variability in hydrographic conditions and nutrient availability.

  17. The epizoic diatom community on four bryozoan species from Helgoland (German Bight, North Sea)

    NASA Astrophysics Data System (ADS)

    Wuchter, Cornelia; Marquardt, Jrgen; Krumbein, Wolfgang

    2002-09-01

    The composition of the diatom community on the bryozoans Electra pilosa, Membranipora membranacea, Flustra foliacea, and Alcyonidium gelatinosum from the German Bight was studied by light and scanning electron microscopy. In total, members of 26 diatom genera were found, with Cocconeis, Tabularia, Licmophora, Amphora, and Navicula being the most abundant. The amount and the composition of the diatom covering seem to be typical for single bryozoan species. Electra pilosa and Membranipora membranacea showed a rather dense covering with 71-547 cells/mm2 and 77-110 cells/mm2, respectively. The most prominent genus on Electra pilosa was Cocconeis, reaching up to 58% of all diatoms in one sample, followed by Navicula, Tabularia and Amphora. The most abundant genera on Membranipora membranacea were Tabularia and Licmophora, making up almost 70% of all diatoms in one sample, followed by Navicula, Cocconeis and Amphora. The diatom composition was very stable on all Electra samples, but varied on Membranipora samples. With <1-27 cells/mm2, diatoms were much less abundant on Alcyonidium gelatinosum. Members of the genera Tabularia and Navicula were the most frequently found benthic diatoms, whereas the planktonic forms Coscinodiscus, Cyclotella, and Thalassiosira made up 35% of the diatoms. On Flustra foliacea, diatoms were virtually absent, with fewer than 5 cells/mm2. The low diatom numbers are probably due to toxic metabolites produced by the host. The same may be true for Alcyonidium gelatinosum, but here they might also be a consequence of the surface properties of the bryozoan.

  18. Settling fluxes of diatoms to the interior of the Antarctic circumpolar current along 170 W

    NASA Astrophysics Data System (ADS)

    Grigorov, Ivo; Rigual-Hernandez, Andrs S.; Honjo, Susumu; Kemp, Alan E. S.; Armand, Leanne K.

    2014-11-01

    An array of four sediment trap moorings recorded the particulate flux across the Antarctic Circumpolar Current (ACC) at 170 W, between November 1996 and January 1998, as part of the US JGOFS-Antarctic Environment and Southern Ocean Process Study (AESOPS) program. The trap locations represent sampling within the Polar Frontal Zone, the Antarctic Polar Front, the Antarctic Zone and the Southern Antarctic Zone. Here we report observations from 1000 m below the sea-surface compared to seafloor and surface water distributions. Sub-sample splits from each trap were obtained and total diatom flux and species composition were determined. The diatom fluxes were quantified using both a dilution and a spike' method to allow for the rapid repeatability of measurements. Diatom flux was found to be highly seasonal across the ACC particularly at higher latitudes. Marine snow aggregates of intact diatom cells and chains were the major components of the biogenic flux. Siliceous particle size was noted to decrease with increasing latitude, which could be aligned with a shift of the diatom assemblage to small-size species/sea-ice affiliated species. A double-structured' diatom flux was recorded at the location of the Antarctic Polar Front trap, with a shift in the diatom assemblage from larger to smaller diatoms in the second flux episode. The sediment trap assemblage shows deviations from the surface water assemblage, while surface sediment samples indicate that significant dissolution occurs after 1000 m and at the sediment-water interface. Estimation of diatom biovolumes across the ACC shows that large diatoms have the potential to greatly impact biogenic fluxes to the ocean interior despite their low fluxes. Small species of the genus Fragilariopsis could potentially export as much Corg as Fragilariopsis kerguelensis near the retreating ice edge. However, their low abundance in the surface sediments also suggests that these diatoms are a shallow export species.

  19. Fate of the Inner Nuclear Membrane Protein Lamin B Receptor and Nuclear Lamins in Herpes Simplex Virus Type 1 Infection

    PubMed Central

    Scott, Emily S.; O'Hare, Peter

    2001-01-01

    During herpesvirus egress, capsids bud through the inner nuclear membrane. Underlying this membrane is the nuclear lamina, a meshwork of intermediate filaments with which it is tightly associated. Details of alterations to the lamina and the inner nuclear membrane during infection and the mechanisms involved in capsid transport across these structures remain unclear. Here we describe the fate of key protein components of the nuclear envelope and lamina during herpes simplex virus type 1 (HSV-1) infection. We followed the distribution of the inner nuclear membrane protein lamin B receptor (LBR) and lamins A and B2 tagged with green fluorescent protein (GFP) in live infected cells. Together with additional results from indirect immunofluorescence, our studies reveal major morphologic distortion of nuclear-rim LBR and lamins A/C, B1, and B2. By 8 h p.i., we also observed a significant redistribution of LBR-GFP to the endoplasmic reticulum, where it colocalized with a subpopulation of cytoplasmic glycoprotein B by immunofluorescence. In addition, analysis by fluorescence recovery after photobleaching reveals that LBR-GFP exhibited increased diffusional mobility within the nuclear membrane of infected cells. This is consistent with the disruption of interactions between LBR and the underlying lamina. In addition to studying stably expressed GFP-lamins by fluorescence microscopy, we studied endogenous A- and B-type lamins in infected cells by Western blotting. Both approaches reveal a loss of lamins associated with virus infection. These data indicate major disruption of the nuclear envelope and lamina of HSV-1-infected cells and are consistent with a virus-induced dismantling of the nuclear lamina, possibly in order to gain access to the inner nuclear membrane. PMID:11507226

  20. Diatom Communities and Metrics as Indicators of Urbanization Effects on Streams and Potential Moderation by Landscape Green Infrastructure

    EPA Science Inventory

    Diatoms are very useful and important indicators of anthropogenic impacts on streams because they are the foundation of primary production and are responsive to nutrients, conductivity, and habitat conditions. We characterized relationships of diatom assemblages with water chemis...

  1. Analysis of local delaminations and their influence on composite laminate behavior

    NASA Technical Reports Server (NTRS)

    Obrien, T. K.

    1984-01-01

    An equation was derived for the strain energy release rate, G, associated with local delamination growth from a matrix ply crack. The critical GC for edge delamination onset in 25/902s graphite epoxy laminates was measured and used in this equation to predict local delamination onset strains in 25/90ns, n = 4, 6, 8 laminates. A simple technique for predicting strain concentrations in the primary load bearing plies near local delaminations was developed. These strain concentrations were responsible for reduced laminate nominal failure strains in laminates containing local delaminations. The influence of edge delamination and matrix crack tip delamination on laminate stiffness and strength was compared.

  2. An experimental investigation on the three-point bending behavior of composite laminate

    NASA Astrophysics Data System (ADS)

    A, Azzam; W, Li

    2014-08-01

    The response of composite laminate structure to three-point bending load was investigated by subjecting two types of stacking sequences of composite laminate structure by using electronic universal tester (Type: WDW-20) machine. Optical microscope was selected in order to characterize bending damage, delamination, and damage shapes in composite laminate structures. The results showed that the [0/90/-45/45]2s exhibits a brittle behavior, while other laminates exhibit a progressive failure mode consisting of fiber failure, debonding (splitting), and delamination. The [45/45/90/0]2s laminate has a highly nonlinear load- displacement curve due to compressive yielding.

  3. A Micromechanics-Based Damage Model for [+/- Theta/90n]s Composite Laminates

    NASA Technical Reports Server (NTRS)

    Mayugo, Joan-Andreu; Camanho, Pedro P.; Maimi, Pere; Davila, Carlos G.

    2006-01-01

    A new damage model based on a micromechanical analysis of cracked [+/- Theta/90n]s laminates subjected to multiaxial loads is proposed. The model predicts the onset and accumulation of transverse matrix cracks in uniformly stressed laminates, the effect of matrix cracks on the stiffness of the laminate, as well as the ultimate failure of the laminate. The model also accounts for the effect of the ply thickness on the ply strength. Predictions relating the elastic properties of several laminates and multiaxial loads are presented.

  4. A geometrically nonlinear analysis of interlaminar stresses in unsymmetrically laminated plates subjected to inplane mechanical loading

    NASA Technical Reports Server (NTRS)

    Norwood, D. Scott; Shuart, Mark J.; Herakovich, Carl T.

    1991-01-01

    The present analysis of interlaminar stresses in unsymmetrically laminates plates gives attention to the linear elastic large-deflection response of square laminated composite plates subjected to either uniaxial tension or compression loading. The effects of Poisson-ratio and mutual-influence coefficient mismatching between adjacent layers is evaluated in both cross-ply and angle-ply, and symmetric and asymmetric laminates. A global/local analysis procedure is used to obtain improved free-edge depictions; the results obtained indicate that the out-of-plane deflections of the unsymmetric laminates reduce interlaminar shear stresses, while reducing interlaminar normal stresses in some laminates and increasing them in others.

  5. Preliminary investigation of crack arrest in composite laminates containing buffer strips

    NASA Technical Reports Server (NTRS)

    Goree, J. G.

    1978-01-01

    The mechanical properties of some hybrid buffer strip laminates and the crack arrest potential of laminates containing buffer strips were determined. The hybrid laminates consisted of graphite with either S-glass, E-glass, or Kevlar. Unnotched tensile coupons and center-cracked fracture coupons were tested. Elastic properties, complete stress/strain curves, and critical stress intensity values are given. The measured elastic properties compare well with those calculated by classical lamination theory for laminates with linear stress/strain behavior. The glass hybrids had more delamination and higher fracture toughness than the all-graphite or the Kevlar hybrid.

  6. Effect of Molding Conditions on Adhesive Property of Laminated Bamboo Composites

    NASA Astrophysics Data System (ADS)

    Matsukawa, Hirohito; Takagi, Hitoshi

    This paper deals with the adhesion strength of laminated bamboo composites fabricated only from steam-exploded bamboo plates by using a hot-pressing method. The adhesion strength of laminated bamboo composites were evaluated by a short beam bending teats. The effects of molding conditions on the shear strength were examined by changing the molding temperature, time, and pressure. The optimum molding conditions of the laminated bamboo composites are 140C, 30 min. and 10 MPa among the conditions investigated. The maximum shear strength of the laminated bamboo composites was approximately 46 MPa, and this value is comparable to that of single plate bamboo composites without lamination.

  7. A limiting analysis for edge effects in angle-ply laminates

    NASA Technical Reports Server (NTRS)

    Hsu, P. W.; Herakovich, C. T.

    1976-01-01

    A zeroth order solution for edge effects in angle ply composite laminates using perturbation techniques and a limiting free body approach was developed. The general method of solution for laminates is developed and then applied to the special case of a graphite/epoxy laminate. Interlaminar stress distributions are obtained as a function of the laminate thickness to width ratio h/b and compared to existing numerical results. The solution predicts stable, continuous stress distributions, determines finite maximum tensile interlaminar normal stress for two laminates, and provides mathematical evidence for singular interlaminar shear stresses.

  8. A Micromechanics-Based Damage Model For The Strength Prediction of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Camanho, Pedro P.; Mayugo, Joan A.; Maimi, Pere; Davila, Carlos G.

    2006-01-01

    A new damage model based on a micromechanical analysis of cracked [+/-0deg/90deg(sub n)]s laminates subjected to multiaxial loads is proposed. The model predicts the onset and accumulation of transverse matrix cracks in uniformly stressed laminates, the effect of matrix cracks on the stiffness of the laminate, as well as the ultimate failure of the laminate. The model also accounts for the effect of the ply thickness on the ply strength. Predictions relating the elastic properties of several laminates and multiaxial loads are presented.

  9. Organic light-emitting diodes formed by soft contact lamination

    E-print Network

    Rogers, John A.

    Organic light-emitting diodes formed by soft contact lamination Tae-Woo Lee* , Jana Zaumseil, 2003 (received for review July 5, 2003) Although tremendous progress has been made in organic light against an electroluminescent organic. This method relies only on van der Waals interactions to establish

  10. Multiscale modeling of damage in multidirectional composite laminates

    E-print Network

    Singh, Chandra Veer

    2009-05-15

    . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 VIII CONCLUSIONS AND FUTURE DIRECTIONS : : : : : : : : : 197 REFERENCES : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 201 VITA : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 225 x LIST...,87]). : : : 34 13 Accumulation of intralaminar cracks in an o -axis ply of a com- posite laminate. The gure is redrawn from [55], based on X-ray radiographs reported in [99]. : : : : : : : : : : : : : : : : : : : : : : : 35 xii FIGURE Page 14 Spacing of cracks...

  11. FEA OF THE HORSETAIL CREEK BRIDGE STRENGTHENED WITH FRP LAMINATES

    E-print Network

    Yim, Solomon C.

    beams. #12;In this paper, three-dimensional finite element bridge models using ANSYS software. Kachlakev, Thomas H. Miller, and Solomon C.S. Yim ABSTRACT A three-dimensional finite element (FE) model strengthening with FRP laminates. Nonlinear finite element analysis is performed using the ANSYS finite element

  12. A lamination technique of LCP\\/Cu for electronic packaging

    Microsoft Academic Search

    T. Suga; A. Takahashi; M. Howlader; K. Saijo; S. Oosawa

    2002-01-01

    Liquid crystalline polymer (LCP) is expected to be used for the lamination of electronic circuit boards because of its excellent mechanical and electric properties, such as a low dielectric constant and dimensional stability. However, it has not been widely used yet due to the weak interaction between LCP and Cu. Roughened surfaces of Cu foil that could deteriorate the electrical

  13. An empirical modified fatigue damage model for impacted GFRP laminates

    NASA Astrophysics Data System (ADS)

    Naderi, S.; Hassan, M. A.; Bushroa, A. R.

    2014-10-01

    The aim of the present paper is to evaluate the residual strength of GFRP laminates following a low-velocity impact event under cyclic loading. The residual strength is calculated using a linear fatigue damage model. According to an investigation into the effect of low-velocity impact on the fatigue behavior of laminates, it seems laminate fatigue life decreases after impact. By normalizing the fatigue stress against undamaged static strength, the Fatigue Damage parameter FD is presented with a linear relationship as its slope which is a linear function of the initial impact energy; meanwhile, the constants were attained from experimental data. FD is implemented into a plane-stress continuum damage mechanics based model for GFRP composite laminates, in order to predict damage threshold in composite structures. An S-N curve is implemented to indicate the fatigue behavior for 2 mm thickness encompassing both undamaged and impacted samples. A decline in lifespan is evident when the impact energy level increases. Finally, the FD is intended to capture the unique GFRP composite characteristics.

  14. Analysis of rectangular laminated composite plates via FSDT meshless method

    Microsoft Academic Search

    J. Wang; K. M. Liew; M. J. Tan; S. Rajendran

    2002-01-01

    A meshless approach based on the reproducing kernel particle method is developed for the flexural, free vibration and buckling analysis of laminated composite plates. In this approach, the first-order shear deformation theory (FSDT) is employed and the displacement shape functions are constructed using the reproducing kernel approximation satisfying the consistency conditions. The essential boundary conditions are enforced by a singular

  15. Aging of GFRP laminates and confinement of concrete columns

    Microsoft Academic Search

    Manuel A. G. Silva

    2007-01-01

    Mechanical properties of fiber reinforced polymers (GFRP) laminates change with water sorption, solar rays or cycles of lowhigh humidity and their degradation is studied under accelerated aging. The results showed that (i) the Youngs modulus of plates suffers only minor changes; (ii) moisture exposure by immersion in water causes only minor degradation; (iii) thermal cycles of small amplitude, around room

  16. Evaluation of laminated aluminum plate for shuttle applications

    NASA Technical Reports Server (NTRS)

    Martin, M. J.

    1973-01-01

    Flaw growth behavior in roll diffusion bonded and adhesive bonded 2219-T87 aluminum alloy was compared to that in monolothic 2219-T87. Based on tests at 40 KSI cyclic stress, for equivalent cyclic life, a .004 interlayer laminate can tolerate a surface flaw twice as wide as in monolithic material, or provide an 8% weight saving by operating at higher stress for the same initial flaw. Roll diffusion bonded material with three structural plies of 2219-T87 and two interlayers of 1100 aluminum was prepared with interlayer thicknesses of .004, .007 and .010 in. Total laminate thickness was .130 in. The .004 interlayer laminate was most effective and gave better results than monolithic material at 40 and 48 ksi. Adhesive bonded specimens were fabricated of three sheets of 2219-T87 aluminum alloy bonded with METLBOND 329 adhesive. Adhesive bonded specimens gave longer lives to failure than diffusion bonded specimens at 40 ksi the diffusion bonded material was superior. Flaws initiated in one ply of the laminate grew to the edges of the specimen in that ply but did not propagate into adjacent plies.

  17. Space filling curves and geodesic laminations Victor F. Sirvent

    E-print Network

    Sirvent, Víctor F.

    an expanding dynamical system on the laminations. AMS subject classification (2000): 28A80, 53C22. Key words´ivar, Apartado 89000, Caracas 1086-A, Venezuela. e-mail: vsirvent@usb.ve 1 #12;In section 4.1 we present

  18. Delamination failure in a unidirectional curved composite laminate

    NASA Technical Reports Server (NTRS)

    Martin, Roderick H.

    1990-01-01

    Delamination failure in a unidirectional curved composite laminate was investigated. The curved laminate failed unstably by delaminations developing around the curved region of the laminate at different depths through the thickness until virtually all bending stiffness was lost. Delamination was assumed to initiate at the location of the highest radial stress in the curved region. A closed form curved beam elasticity solution and a 2-D finite element analysis (FEA) were conducted to determine this location. The variation in the strain energy release rate, G, with delamination growth was then determined using the FEA. A strength-based failure criteria adequately predicted the interlaminar tension failure which caused initial delamination onset. Using the G analysis the delamination was predicted to extend into the arm and leg of the laminate, predominantly in mode I. As the initial delamination grew arould the curved region, the maximum radial stress in the newly formed inner sublaminate increased to a level sufficient to cause a new delamination to initiate in the sublaminate with no increase in applied load. This failure progression was observed experimentally.

  19. Laminated plastic microfluidic components for biological and chemical systems

    SciTech Connect

    Martin, P.M.; Matson, D.W.; Bennett, W.D.; Lin, Y.; Hammerstrom, D.J. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)] [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

    1999-07-01

    Laminated plastic microfluidic components are being developed for biological testing systems and chemical sensors. Applications include a DNA thermal cycler, DNA analytical systems, electrophoretic flow systems, dialysis systems, and metal sensors for ground water. This article describes fabrication processes developed for these plastic microfluidic components, and the fabrication of a chromium metal sensor and a microdialysis device. Most of the components have a stacked architecture. Using this architecture, the fluid flows, or is pumped through, as many as nine laminated functional levels. Functions include pumping, mixing, reaction, detection, reservoirs, separations, and electronics. Polyimide, poly(methylmethacrylate) (PMMA), and polycarbonate materials with thicknesses between 25 and 125 {mu}m are used to construct the components. This makes the components low cost, inert to many biological fluids and chemicals, and disposable. The components are fabricated by excimer laser micromachining the microchannel patterns and microstructures in the various laminates. In some cases, micropumps are integrated into these components to move the fluids. Vias and interconnects are also cut by the laser and integrated with micropumps. The laminates are sealed and bonded by adhesive and thermal processes and are leak tight. The parts withstand pressures as high as 790 kPa. Typical channel widths are 50 to 100 {mu}m, with aspect ratios near 5. {copyright} {ital 1999 American Vacuum Society.}

  20. Direct oven-tempered hybrid composite-resin laminate veneers.

    PubMed

    Birnbaum, N S

    1992-01-01

    The difficulty in achieving optimal aesthetics of the single-tooth indirect laminate veneer has prompted the author to develop a direct technique for fabricating oven-tempered hybrid composite resin veneers. These restorations exhibit excellent physical properties, marginal integrity, and aesthetics. PMID:1391925

  1. Low Velocity Impact Damage to Carbon/Epoxy Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    2011-01-01

    Impact damage tends to be more detrimental to a laminate's compression strength as compared to tensile strength. Proper use of Non Destructive Evaluation (NDE) Techniques can remove conservatism (weight) from many structures. Test largest components economically feasible as coupons. If damage tolerance is a driver, then consider different resin systems. Do not use a single knockdown factor to account for damage.

  2. Magnetoelectric nonlinearity in magnetoelectric laminate sensors Liangguo Shen,1,a)

    E-print Network

    Boyer, Edmond

    Magnetoelectric nonlinearity in magnetoelectric laminate sensors Liangguo Shen,1,a) Menghui Li,1 2011; accepted 27 October 2011; published online 5 December 2011) A nonlinearity in the magnetoelectric sensors based on the magneto-electric (ME) effect have been widely investigated.410 The ME effect

  3. Dynamic delamination crack propagation in a graphite/epoxy laminate

    NASA Technical Reports Server (NTRS)

    Grady, J. E.; Sun, C. T.

    1991-01-01

    Dynamic delamination crack propagation in a (90/0) 5s Graphite/Epoxy laminate with an embedded interfacial crack was investigated experimentally using high speed photography. The dynamic motion was produced by impacting the beamlike laminate specimen with a silicon rubber ball. The threshold impact velocities required to initiate dynamic crack propagation in laminates with varying initial crack positions were determined. The crack propagation speeds were estimated from the photographs. Results show that the through the thickness position of the embedded crack can significantly affect the dominant mechanism and the threshold impact velocity for the onset of crack movement. If the initial delamination is placed near the top of bottom surface of the laminate, local buckling of the delaminated plies may cause instability of the crack. If the initial delamination lies on the midplane, local buckling does not occur and the initiation of crack propagation appears to be dominated by Mode II fracture. The crack propagation and arrest observed was seen to be affected by wave motion within the delamination region.

  4. Low-Velocity Impact and Damage Process of Composite Laminates

    Microsoft Academic Search

    Zhidong Guan; Chihdar Yang Yang

    2002-01-01

    Several important issues regarding damage simulation of composite laminates due to low velocity impact were investigated including contact law, damage initiation and the corresponding change of stiffness, and damping. Continuum damage mechanics was applied to account for the change of mechanical properties of damaged materials. The Hertzian contact law was modified in order to accommodate the serious damage in the

  5. A method for observing gas evolution during plastic laminate cure

    NASA Technical Reports Server (NTRS)

    Nicholls, A. H.

    1969-01-01

    Polyimide, phenolic, and other resins which develop volatiles during laminating or molding cure are studied using optimum cure cycles. The specimen is placed on a platen and sealed in a plastic bag, then heated and observed for gas evolution using a binocular microscope. A cover plate is added to sumulate an autoclave.

  6. Thermomechanical analysis of the laminated object manufacturing (LOM) process

    Microsoft Academic Search

    Fazil O. Sonmez; H. Thomas Hahn

    1998-01-01

    LOM is one of the techniques for rapid prototyping, which is used to build three-dimensional solid objects. In this paper, a numerical analysis of the thermomechanical behavior of a laminate during the LOM process is presented. Models were developed to describe heat transfer and deformation phenomena. These models are incorporated into computer codes to generate numerical results. The numerical results

  7. Statistical Theory of Strength of Laminated Composites II

    Microsoft Academic Search

    Peter M. Scop; Ali S. Argon

    1969-01-01

    The statistical theory for fracture of laminated composites devel oped previously has been extended to take account of stress enhance ment in neighboring elements around primary fractures. The results show that: a) the effective stress enhancement is less for an elastic matrix than for a rigid-plastic matrix, b) for constant length the strength of the composites rise with increasing numbers

  8. The Influence of Stacking Sequence on Laminate Strength

    Microsoft Academic Search

    N. J. Pagano; R. Byron Pipes

    1971-01-01

    Based upon considerations relating to the nature of the inter laminar stresses in composite laminates, an approach is presented to predict the detailed stacking sequence of specific layer orientations which leads to optimum protection against delamination under uniaxial static and fatigue loadings. In particular, it is argued that the interlaminar normal stress, as well as the interlaminar shear stress, is

  9. On damage development in mechanically fastened composite laminates

    Microsoft Academic Search

    Tomas Ireman; Tron Ranvik; Ingvar Eriksson

    2000-01-01

    A comprehensive experimental program was conducted to measure and characterize the development of damage in the vicinity of fastener holes in graphite\\/epoxy composite laminates. This was carried out to generate data which can be used for development of appropriate failure criteria. Test specimens were loaded in quasi-static cycles with successively increasing loads, and damage development in the vicinity of the

  10. Axisymmetric Vibrations and Dissipative Heating of a Laminated Inelastic Disk

    Microsoft Academic Search

    Ya. A. Zhuk; I. K. Senchenkov; G. A. Tabieva; O. P. Chervinko

    2002-01-01

    The coupled thermomechanical dynamic behavior of an inhomogeneous body is investigated for a partial case where a laminated inelastic disc is subject to forced axisymmetric vibrations and dissipative heating. The problem is solved in complete and approximate formulations. In the former case, the behavior of the material is described using generalized flow theory. In the latter case, the behavior of

  11. Transverse Vibrations of Laminated Beams in Three-Dimensional Formulation

    Microsoft Academic Search

    G. L. Gorynin; Yu. V. Nemirovskii

    2005-01-01

    A new asymptotic method is proposed to describe the free and forced transverse vibrations of elastic laminated beams of arbitrary cross section using the three-dimensional elastic equations without additional hypotheses and constraints. For beams with layers of equal Poisson's ratio, the zero-order natural frequencies are equal to the natural frequencies predicted by classical beam theory based on the Bernoulli hypothesis.

  12. Phenolic laminate solar absorber panel and method of making

    Microsoft Academic Search

    Severson

    1979-01-01

    A solar flat plate absorber panel is molded from a laminate consisting of a suitable web material impregnated with a thermosetting phenolic resin. The absorber plate is pressure formed from superimposed layers of material and mold-cured to produce a unitary structure having a first or solar radiation absorbing surface on one side and an integral closed hollow lattice work of

  13. Thermoviscoelastic characterization and prediction of Kevlar/epoxy composite laminates

    NASA Technical Reports Server (NTRS)

    Gramoll, K. C.; Dillard, D. A.; Brinson, H. F.

    1990-01-01

    The thermoviscoelastic characterization of Kevlar 49/Fiberite 7714A epoxy composite lamina and the development of a numerical procedure to predict the viscoelastic response of any general laminate constructed from the same material were studied. The four orthotropic material properties, S sub 11, S sub 12, S sub 22, and S sub 66, were characterized by 20 minute static creep tests on unidirectional (0) sub 8, (10) sub 8, and (90) sub 16 lamina specimens. The Time-Temperature Superposition-Principle (TTSP) was used successfully to accelerate the characterization process. A nonlinear constitutive model was developed to describe the stress dependent viscoelastic response for each of the material properties. A numerical procedure to predict long term laminate properties from lamina properties (obtained experimentally) was developed. Numerical instabilities and time constraints associated with viscoelastic numerical techniques were discussed and solved. The numerical procedure was incorporated into a user friendly microcomputer program called Viscoelastic Composite Analysis Program (VCAP), which is available for IBM PC type computers. The program was designed for ease of use. The final phase involved testing actual laminates constructed from the characterized material, Kevlar/epoxy, at various temperatures and load level for 4 to 5 weeks. These results were compared with the VCAP program predictions to verify the testing procedure and to check the numerical procedure used in the program. The actual tests and predictions agreed for all test cases which included 1, 2, 3, and 4 fiber direction laminates.

  14. Fatigue damage mechanisms in (0, 90) s composite laminate

    Microsoft Academic Search

    E. Petitpas; M. Renault; D. Valentin

    1989-01-01

    The high strength to weight ratio of CFRP composite materials is certainly an attractive structural characteristic. However, in many circumstances consideration must also be given to the fatigue properties. It is well established by now that the failure of multidirectional composite laminates during either monotonic load or fatigue initiates in the plies that are most desoriented with respect to the

  15. Laminates of Thin Ferromagnetic Films for Microwave Applications

    Microsoft Academic Search

    K. N. Rozanov; I. T. Iakubov; A. N. Lagarkov; S. A. Maklakov; A. V. Osipov; D. A. Petrov; L. Ryzhikov; M. V. Sedova; S. N. Starostenko

    2007-01-01

    Thin ferromagnetic films are known to exhibit the highest possible microwave permeability of known magnetic materials. Magnetic materials with high microwave magnetic performance are useful for many technical applications. However, bulk rather than planar materials are frequently needed for the applications. Bulk materials with high microwave permeability may be produced as laminated structures of thin ferromagnetic films, possibly patterned. The

  16. Multimodal vibration control of laminated composite plates using piezoceramic materials

    Microsoft Academic Search

    Young K. Kang; Moon H. Kim; Hyun C. Park; Woonbong Hwang; Kyung S. Han

    1996-01-01

    Multi-modal vibration control of laminated composite plates using collocated piezoelectric sensor\\/actuator is analyzed theoretically and verified experimentally for various fiber orientations. The modal damping (2(zetz) (omega) ) is chosen as a performance index rather than the damping ratio ((zetz) ) for the vibration suppression in the structure. The active modal dampings of the first bending and the first torsional modes

  17. Optimum design of composite laminates using genetic algorithms

    Microsoft Academic Search

    Kelvin J. Callahan

    1992-01-01

    The use of genetic algorithms (GAs) for the design of composite laminates is presented. Unlike the traditional hill-climbing techniques, GAs are global search procedures based on the mechanics of natural selection with the result that they are robust over a wide range of environments, particularly the multimodal search spaces encountered in composite design. The GA requires coding of the design

  18. Stress Fracture Criteria for Laminated Composites Containing Stress Concentrations

    Microsoft Academic Search

    J. M. Whitney; R. J. Nuismer

    1974-01-01

    Two related criteria based on stress distribution are presented for predicting the uniaxial tensile strength of laminated composites containing through the thickness discontinuities of a general shape. The criteria result in two parameter (unnotched tensile strength and a characteristic dimension) models which are capable of predicting observed discontinuity size effects without resorting to classical concepts of linear elastic fracture mechanics.

  19. DIATOM INDICES OF STREAM ECOSYSTEM CONDITIONS: COMPARISON OF GENUS VS. SPECIES LEVEL IDENTIFICATIONS

    EPA Science Inventory

    Diatom assemblage data collected between 1993 and 1995 from 233 Mid-Appalachian streams were used to compare indices of biotic integrity based on genus vs. species level taxonomy. Thirty-seven genera and 197 species of diatoms were identified from these samples. Metrics included...

  20. The Genome of the Diatom Thalassiosira Pseudonana: Ecology, Evolution and Metabolism

    Microsoft Academic Search

    E V Armbrust; J A Berges; C Bowler; B R Green; D Martinez; N H Putnam; S Zhou; A E Allen; K E Apt; M Bechner; M A Brzezinski; B K Chaal; A Chiovitti; A K Davis; M S Demarest; J C Detter; T G del Rio; D Goodstein; M Z Hadi; U Hellsten; M Hildebrand; B D Jenkins; J Jurka; V V Kapitonov; N Kroger; W Y Lau; F W Larimer; J C Lippmeier; S Lucas; M Medina; A Montsant; M Obornik; M S Parker; B Palenik; G J Pazour; P M Richardson; T A Rynearson; M A Saito; D C Schwartz; K Thamatrakoln; K Valentin; A Vardi; F P Wilkerson; D S Rokhsar

    2005-01-01

    Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for 20% of global carbon fixation. We report the 34 Mbp draft nuclear genome of the marine diatom, Thalassiosira pseudonana and its 129 Kbp plastid and 44 Kbp mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid

  1. Diversity of the cadmium-containing carbonic anhydrase in marine diatoms and natural waters

    E-print Network

    Morel, François M. M.

    sequence found in the Thalassiosira pseudonana genome encodes a peptide of 238 amino acids with a molecular as its metal centre in the coastal diatom Thalassiosira weissflogii has led us to search of Thalassiosira pseud- onana, we show that CDCA is widespread in diatom species and ubiquitous in the environment

  2. The Transcriptome and Proteome of the Diatom Thalassiosira pseudonana Reveal a Diverse Phosphorus

    E-print Network

    Benitez-Nelson, Claudia

    The Transcriptome and Proteome of the Diatom Thalassiosira pseudonana Reveal a Diverse Phosphorus Thalassiosira pseudonana grown under P-replete and P-deficient conditions. A total of 318 transcripts were ML, et al. (2012) The Transcriptome and Proteome of the Diatom Thalassiosira pseudonana Reveal

  3. Gene biomarkers in diatom Thalassiosira pseudonana exposed to polycyclic aromatic hydrocarbons from contaminated marine surface sediments

    Microsoft Academic Search

    Raquel N. Carvalho; Alina D. Burchardt; Fabrizio Sena; Giulio Mariani; Anne Mueller; Stephanie K. Bopp; Gunther Umlauf; Teresa Lettieri

    2011-01-01

    Marine diatoms have a key role in the global carbon fixation and therefore in the ecosystem. We used Thalassiosira pseudonana as a model organism to assess the effects of exposure to environmental pollutants at the gene expression level. Diatoms were exposed to polycyclic aromatic hydrocarbons mixture (PAH) from surface sediments collected at a highly PAH contaminated area of the Mediterranean

  4. Gene regulation in the marine diatom Thalassiosira pseudonana upon exposure to polycyclic aromatic hydrocarbons (PAHs)

    Microsoft Academic Search

    Stephanie K. Bopp; Teresa Lettieri

    2007-01-01

    Diatoms are eukaryotic algae, which can be found worldwide in oceans and freshwaters. These organisms are ecologically relevant due to their key role in the global carbon cycle, contributing to about 25% to the global primary production [Falciatore, A., Bowler, C., 2002. Revealing the molecular secrets of marine diatoms. Annu. Rev. Plant Biol. 53, 109130].We investigated the effects of three

  5. The incorporation of zinc and iron into the frustule of the marine diatom Thalassiosira pseudonana

    Microsoft Academic Search

    Michael J. Ellwood; Keith A. Hunter

    2000-01-01

    Zinc and iron uptake experiments were conducted with the marine diatom Thalassosira pseudonana,to investigate whether Zn and Fe are incorporated into the frustule of this diatom. Our results show that the uptake and deposition of Zn into opal has a sigmoidal relationship with the free Zn 21 concentration of the culture medium. The amount of Zn incorporated into the opal

  6. A synthesis of post-glacial diatom records from Lake Baikal

    Microsoft Academic Search

    J. Platt Bradbury; Ye. V. Bezrukova; G. P. Chernyaeva; S. M. Colman; G. Khursevich; J. W. King; Ye. V. Likoshway

    1994-01-01

    The biostratigraphy of fossil diatoms contributes important chronologic, paleolimnologic, and paleoclimatic information from Lake Baikal in southeastern Siberia. Diatoms are the dominant and best preserved microfossils in the sediments, and distinctive assemblages and species provide inter-core correlations throughout the basin at millennial to centennial scales, in both high and low sedimentation-rate environments. Distributions of unique species, once dated by radiocarbon,

  7. The Distribution of Diatoms Near a Thermal Bar in Lake Baikal

    Microsoft Academic Search

    Yelena V. Likhoshway; Anna Ye. Kuzmina; Tatyana G. Potyemkina; Vladimir L. Potyemkin; Michael N. Shimaraev

    1996-01-01

    Studies of the spatial distribution of suspended matter and of diatoms across a thermal bar in Lake Baikal revealed that waters sinking at the thermal bar front (2 km off-shore) move to the bottom along the underwater slope, and may be traced to a depth of at least 700 m, 5 km off-shore. The distributions of 11 diatom species across

  8. Iron enrichment stimulates toxic diatom production in high-nitrate, low-chlorophyll areas

    E-print Network

    Cochlan, William P.

    Iron enrichment stimulates toxic diatom production in high-nitrate, low-chlorophyll areas Charles G-scale iron fertilizations to help mitigate global climate change. Controversy surrounds these initiatives experiments have shown that iron additions stimulate growth of the toxigenic diatom genus Pseudonitzschia

  9. Relationships between surface sediment diatom assemblages and lakewater characteristics in Adirondack Lakes

    SciTech Connect

    Charles, D.F.

    1985-06-01

    Relationships between surface sediment diatom assemblages and lakewater characteristics were studied in 38 lakes in the Adirondack Mountains of northern New York. Most of the lakes are dilute, poorly buffered, and oligotrophic to mesotrophic. The diatom flora typical for circumneutral to acidic lakes. The purposes of this study were to identify the environmental factors most strongly related to the distributions of diatom taxa and the overall composition of diatom assemblages, and to derive equations to infer lakewater pH from diatom assemblage data. Relationships between diatom assemblages and environmental gradients were analyzed using reciprocal averaging ordination (RA). Correlations between Ra axis 1 and pH-related factors were strong. Correlations were weaker (but still statistically significant) with elevation, epilimnion temperature, and concentrations of SO/sub 4/, Cl, and Si. Total P, chlorophyll a, water color, and mean depth were not important in explaining differences among assemblages. Predictive equations were derived for inferring lakewater pH from diatom assemblage data. Agreement between predicted and measured pH was very good. These predictive relationships can be used to interpret stratigraphic diatom assemblages to reconstruct lake pH histories.

  10. Epilithic and epipelic diatoms in the Sandusky River, with emphasis on species diversity and water pollution

    Microsoft Academic Search

    R. Jan Stevenson

    1984-01-01

    Benthic diatom communities were collected seasonally from silty and rocky substrates to survey the water quality of the Sandusky River. Even though species composition was highly variable along the river, recurrent changes in relative abundance of specific diatom taxa and changes in overall community composition delineated areas where discharge of treated sewage affected water quality of the river. Changes in

  11. Effects of physical disturbance and canopy cover on attached diatom community structure in an Idaho stream

    Microsoft Academic Search

    Christopher T. Robinson; Samuel R. Rushforth

    1987-01-01

    A field experiment was conducted to determine the effect of disturbance frequency on diatom communities established on artificial substrates within an open canopy site and a closed canopy site of a 3rd order stream. The open canopy site (OCS) had a total of 80 diatom taxa colonizing the substrates, while the closed canopy site (CCS) had only 55 taxa. Cluster

  12. Diatoms as an aid in identifying late-Holocene tsunami deposits

    Microsoft Academic Search

    Eileen Hemphill-Haley

    1996-01-01

    Diatoms (Bacillariophyta) help identify the onshore deposits of tsunamis from earthquakes on the Cascadia subduction zone along the Pacific coast of Oregon, Washington, and British Columbia, and on faults high in the North American plate in the Puget Sound area of Washington. At the Copalis River, Washington, diatom analyses suggest that a tsunami deposit about 300 calendric years old (300

  13. Localization and Role of Manganese Superoxide Dismutase in a Marine Diatom1[OA

    E-print Network

    Localization and Role of Manganese Superoxide Dismutase in a Marine Diatom1[OA] Felisa Wolfe-Simon2 by their metal cofactor (iron, manganese [Mn], copper/zinc, nickel), MnSOD is the dominant form in the diatom in four isoforms, recognized by their metal center cofactors (iron [Fe], manganese [Mn], copper [Cu

  14. A global diatom database abundance, biovolume and biomass in the world ocean

    E-print Network

    Boyer, Edmond

    A global diatom database ­ abundance, biovolume and biomass in the world ocean Leblanc1 K for Life Sciences Ecophysiology of Plants, PO Box 11103, 9700 CC Groningen, the Netherlands} [18]{Plymouth published or unpublished datasets regarding diatom distribution in the world ocean. The data obtained

  15. Seasonal and interannual dynamics in diatom production in the Cariaco Basin, Venezuela

    NASA Astrophysics Data System (ADS)

    Romero, O. E.; Thunell, R. C.; Astor, Y.; Varela, R.

    2009-04-01

    We examine the diatom flux collected between November 1996 and April 1998, and between January and October 1999 at the time series study site in the Cariaco Basin, off Venezuela. The temporal dynamics of the total diatom flux mainly reflect seasonal, trade wind-driven changes in surface hydrographic conditions, including changes associated with the El Ni

  16. Recycling and Uptake of Si(OH)4 when Protozoan Grazers Feed on Diatoms

    E-print Network

    Paris-Sud XI, Universit de

    1 Recycling and Uptake of Si(OH)4 when Protozoan Grazers Feed on Diatoms Sabine Schultesa,1 of diatom mortality in the ocean. As part of the microbial loop, protozoan grazers also feed on bacteria and Chaetoceros gracilis, and heterotrophic protozoans, the dinoflagellate Oxyrrhis marina and the ciliate

  17. Diatoms as a source for 4-desmethyl-23,24-dimethyl steroids in sediments and petroleum

    NASA Astrophysics Data System (ADS)

    Rampen, Sebastiaan W.; Schouten, Stefan; Hopmans, Ellen C.; Abbas, Ben; Noordeloos, Anna A. M.; van Bleijswijk, Judith D. L.; Geenevasen, Jan A. J.; Sinninghe Damst, Jaap S.

    2009-01-01

    Analysis of the sterol composition of more than 100 diatom cultures, representing all major marine diatom orders, indicates that this group of algae may be an important source for 4-desmethyl-23,24-dimethyl steroids in sediments and petroleum, as their precursors, i.e. 4-desmethyl-23,24-dimethyl sterols, were present in 22 of the cultures. The phylogenetic positions of diatom species that produce 4-desmethyl-23,24-dimethyl sterols show that, within the centric diatoms, only a specific group of diatoms is able to produce these sterols, while within the pennate diatoms, a phylogenetic relationship between 4-desmethyl-23,24-dimethyl sterol-producing diatoms is less apparent. Based on the phylogenetic relationship, it is suggested that diatoms inherited the ability of producing these sterols from a single common ancestor, which originated between 150 and 100 Ma ago. Co-injection of an authentic 23R,24R-dimethyl-5?-cholestane standard with extracts confirmed its presence in sediments. We also tentatively identified three other 4-desmethyl-23,24-dimethyl sterane isomers having different side-chain stereo-configurations and observed that some of the isomers co-elute with other steranes including 24-ethyl-5?-cholestane.

  18. Seasonal effects of cadmium accumulation in periphytic diatom communities of freshwater biofilms.

    PubMed

    Duong, Thi Thuy; Morin, Soizic; Herlory, Olivier; Feurtet-Mazel, Agns; Coste, Michel; Boudou, Alain

    2008-10-20

    The relationships between diatom species and cadmium (Cd) accumulated in biofilms of the Riou-Mort River (SW, France) were studied in July 2004 and March 2005. Biofilms were sampled from artificial substrates immersed along a metallic pollution gradient during 20 days. Dynamics of diatom communities and cadmium accumulation were followed by collecting samples after 4, 7, 14 and 20 days of biofilm colonization. Cd accumulation in biofilms during experiment was significantly higher in Cd polluted station (Joanis) than in reference station (Firmi) for both seasons. Periphytic diatom composition varied between sites and seasons. At Firmi station, seasonal dynamics of diatom communities were stable with the dominance of Cyclotella meneghiniana and Melosira varians in July and Surirellabrebissonnii and Navicula gregaria in March. At Joanis station, diatom communities mainly responded to high levels of metal by a high proportion of small, adnate species. Positive correlations between Eolimna minima, Nitzschia palea, Encyonema minutum, Surirella angusta, and Gomphonema parvulum and cadmium accumulation were observed, indicating that these species are tolerant to high levels of cadmium. On the other hand, negative correlations of C. meneghiniana, N. gregaria, Navicula lanceolata, M. varians and Nitzschia dissipata with cadmium qualify them as sensitive diatom species. Periphytic diatom composition through the presence of specific species highlight metal tolerant indicator diatom groups which will be meaningful for biomonitoring pollution in natural aquatic systems. PMID:18801587

  19. Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness, and Strength

    E-print Network

    Buehler, Markus J.

    Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness algae that is mainly composed of amorphous silica, which features a hierarchical structure that ranges in diatom algae as a basis to study a bioinspired nanoporous material implemented in crystalline silica. We

  20. autotrophs from diatoms to brown algae... (chlorophylls a + c1 c2 c3)

    E-print Network

    life cycle production of naked flagellates without skeleton #12;Dictyocha recent species Dictyocha autotrophs from diatoms to brown algae... (chlorophylls a + c1 c2 c3) heterotrophs nannoplanktonic, coccoid algae siliceous cell wall composed of oval or three-sided cell wall (similar to diatoms