Sample records for laminated diatom ooze

  1. Choose Your Ooze

    NSDL National Science Digital Library

    Oregon Museum of Science and Industry

    2007-01-01

    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.

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

    Microsoft Academic Search

    A. Chang; T. F. Pedersen

    2009-01-01

    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

  3. 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.

  4. Erodibility of pelagic carbonate ooze in the northeast Atlantic

    Microsoft Academic Search

    K. S Black; O. C Peppe; G Gust

    2003-01-01

    Shipboard erosion experiments were conducted on retrieved carbonate ooze sediments using the suction-stirring flume instrument of Gust and Muller [Gust, G., Muller, V., 1997. Interfacial hydrodynamics and entertainment functions of currently used erosion devices. Burt, N.T., et al. (Eds.) Cohesive Sediments. Wiley, Chichester, pp. 149–176] at two differing localities (site A, 3800 m water depth; site B, 1100 m water

  5. An unusual early Holocene diatom event north of the Getz Ice Shelf (Amundsen Sea): Implications for West Antarctic Ice Sheet development

    NASA Astrophysics Data System (ADS)

    Esper, O.; Gersonde, R.; Hillenbrand, C.; Kuhn, G.; Smith, J.

    2011-12-01

    Modern global change affects not only the polar north but also, and to increasing extent, the southern high latitudes, especially the Antarctic regions covered by the West Antarctic Ice Sheet (WAIS). Consequently, knowledge of the mechanisms controlling past WAIS dynamics and WAIS behaviour at the last deglaciation is critical to predict its development in a future warming world. Geological and palaeobiological information from major drainage areas of the WAIS, like the Amundsen Sea Embayment, shed light on the history of the WAIS glaciers. Sediment records obtained from a deep inner shelf basin north of Getz Ice Shelf document a deglacial warming in three phases. Above a glacial diamicton and a sediment package barren of microfossils that document sediment deposition by grounded ice and below an ice shelf or perennial sea ice cover (possibly fast ice), respectively, a sediment section with diatom assemblages dominated by sea ice taxa indicates ice shelf retreat and seasonal ice-free conditions. This conclusion is supported by diatom-based summer temperature reconstructions. The early retreat was followed by a phase, when exceptional diatom ooze was deposited around 12,500 cal. years B.P. [1]. Microscopical inspection of this ooze revealed excellent preservation of diatom frustules of the species Corethron pennatum together with vegetative Chaetoceros, thus an assemblage usually not preserved in the sedimentary record. Sediments succeeding this section contain diatom assemblages indicating rather constant Holocene cold water conditions with seasonal sea ice. The deposition of the diatom ooze can be related to changes in hydrographic conditions including strong advection of nutrients. However, sediment focussing in the partly steep inner shelf basins cannot be excluded as a factor enhancing the thickness of the ooze deposits. It is not only the presence of the diatom ooze but also the exceptional preservation and the species composition of the diatom assemblage, which point to specific scenarios involving e.g. changes in the food web that can be related to warmer surface water temperatures. Such warming of shelf waters may be related with an overshooting Atlantic Meridional Overturning Circulation (AMOC) and strong injection of warmer North Atlantic Deep Water into the Southern Ocean water masses at Termination I as reported by [2]. Such finding may highlight the effects of AMOC changes on Antarctic ice shelf extent and coastal ecosystems. [1] Hillenbrand et al., 2010. J. Quat. Sci. 25 (3), 280-295. [2] Barker et al., 2010. Nature Geosci. 3, 567-571.

  6. 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.

  7. 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.

  8. 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.

  9. Plasmids in diatom species.

    PubMed Central

    Hildebrand, M; Corey, D K; Ludwig, J R; Kukel, A; Feng, T Y; Volcani, B E

    1991-01-01

    We have discovered plasmids in 5 of 18 diatom species surveyed. In several species, more than one type of plasmid is present. Several of the plasmids show similarity by hybridization previously characterized plasmids in Cylindrotheca fusiformis (J. D. Jacobs et al., unpublished data). Additionally, there is similarity between the plasmids found in C. fusiformis and chloroplast DNA in three diatom species. These results add to the evidence that the plasmids have features of mobile genetic elements. Images PMID:1885558

  10. Zeolitisation of diatoms.

    PubMed

    Anderson, M W; Holmes, S M; Mann, R; Foran, P; Cundy, C S

    2005-01-01

    The development of low cost hierarchical porous materials based upon the zeolitisation of diatomaceous earth for fluid waste benification is described. Two preparative approaches invole: first, using the diatom as a support for zeolite nanocrystals; second, direct pseudomorphic transformation of the diatom into a zeolite. These hierarchical porous materials are potentially useful for important industrial processes in ion-exchange, catalysis and waste benefication. PMID:15762166

  11. Fate of corrosion products released from stainless steel in marine sediments and seawater. Part 3. Calcareous ooze

    SciTech Connect

    Schmidt, R.L.

    1982-04-01

    The physicochemical forms and partitioning of corrosion products released from stainless steel upon exposure to selected environmental conditions is the subject of this investigation. This report describes the influence of calcareous sediment on the rate of release and fate of corrosion products produced when neutron-activated stainless steel specimens were exposed to a Globigerina ooze taken from the Northeast Pacific Ocean. The calcareous ooze used in this study consists largely of planktonic formanifera tests and was found to be about 90% CaCO/sub 3/. The trace metal content of this sediment was typical of average deep-sea carbonate sediments, and the ratios of trace elements to Ti were not remarkably different from a coastal clayey silt or a Northeast Pacific pelagic red clay. Most (>80%) of the trace metals extracted by sequential chemical treatment were associated with reductant-soluble materials, i.e., amorphous Mn and Fe oxides, or were incorporated in the carbonate substrate. Specimens of neutron-activated stainless steel exposed to calcareous ooze suspended in seawater under aerated and non-oxygenated conditions released corrosion products at rates of 1.7 and 4.2 ..mu..g year/sup -1/ cm/sup -2/, respectively. Almost 90% of the corrosion products (/sup 60/Co activity) released under aerated conditions were relatively labile. Of these materials, over 80% were soluble upon treatment with a strong complexing agent, DTPA, indicating that adsorption of corrosion products as cations had been the major mechanism of incorporation into the sediment. In the absence of O/sub 2/, a large fraction (approx. 80%) of the corrosion products were also relatively labile. Larger fractions of the corrosion products were soluble, easily dissolved, or present as carbonates or sulfides under non-oxygenated conditions than they were for the aerated treatment.

  12. 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.

  13. 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

  14. Pasture-associated laminitis.

    PubMed

    Geor, Raymond J

    2009-04-01

    Laminitis is a painful and debilitating condition of horses and ponies that has major economic and welfare implications. Anecdotal observations and the results of survey studies have indicated that most laminitis cases occur in horses and ponies kept at pasture (hence, the term pasture-associated laminitis). Risk for development of pasture-associated laminitis represents a dynamic interaction between animal predisposing factors (an insulin-resistant phenotype commonly termed equine metabolic syndrome) and environmental conditions, particularly the nonstructural carbohydrate (simple sugars, starches, and fructans) content of pasture forage. Countermeasures for avoidance of pasture-associated laminitis involve (1) mitigation of metabolic predisposition (insulin resistance and obesity) in high-risk horses and ponies and (2) dietary and pasture grazing management strategies that minimize exposure to the dietary conditions known to trigger laminitis in susceptible animals. PMID:19303549

  15. Nuclear Lamins and Neurobiology

    PubMed Central

    Jung, Hea-Jin; Lee, John M.

    2014-01-01

    Much of the work on nuclear lamins during the past 15 years has focused on mutations in LMNA (the gene for prelamin A and lamin C) that cause particular muscular dystrophy, cardiomyopathy, partial lipodystrophy, and progeroid syndromes. These disorders, often called “laminopathies,” mainly affect mesenchymal tissues (e.g., striated muscle, bone, and fibrous tissue). Recently, however, a series of papers have identified important roles for nuclear lamins in the central nervous system. Studies of knockout mice uncovered a key role for B-type lamins (lamins B1 and B2) in neuronal migration in the developing brain. Also, duplications of LMNB1 (the gene for lamin B1) have been shown to cause autosome-dominant leukodystrophy. Finally, recent studies have uncovered a peculiar pattern of nuclear lamin expression in the brain. Lamin C transcripts are present at high levels in the brain, but prelamin A expression levels are very low—due to regulation of prelamin A transcripts by microRNA 9. This form of prelamin A regulation likely explains why “prelamin A diseases” such as Hutchinson-Gilford progeria syndrome spare the central nervous system. In this review, we summarize recent progress in elucidating links between nuclear lamins and neurobiology. PMID:24842906

  16. Nuclear lamins and neurobiology.

    PubMed

    Young, Stephen G; Jung, Hea-Jin; Lee, John M; Fong, Loren G

    2014-08-01

    Much of the work on nuclear lamins during the past 15 years has focused on mutations in LMNA (the gene for prelamin A and lamin C) that cause particular muscular dystrophy, cardiomyopathy, partial lipodystrophy, and progeroid syndromes. These disorders, often called "laminopathies," mainly affect mesenchymal tissues (e.g., striated muscle, bone, and fibrous tissue). Recently, however, a series of papers have identified important roles for nuclear lamins in the central nervous system. Studies of knockout mice uncovered a key role for B-type lamins (lamins B1 and B2) in neuronal migration in the developing brain. Also, duplications of LMNB1 (the gene for lamin B1) have been shown to cause autosome-dominant leukodystrophy. Finally, recent studies have uncovered a peculiar pattern of nuclear lamin expression in the brain. Lamin C transcripts are present at high levels in the brain, but prelamin A expression levels are very low-due to regulation of prelamin A transcripts by microRNA 9. This form of prelamin A regulation likely explains why "prelamin A diseases" such as Hutchinson-Gilford progeria syndrome spare the central nervous system. In this review, we summarize recent progress in elucidating links between nuclear lamins and neurobiology. PMID:24842906

  17. A ca. 800Year Lithologic Record of Drought from Sub-annually Laminated Lake Sediment, East Java

    Microsoft Academic Search

    Shelley D. Crausbay; James M. Russell; Douglas W. Schnurrenberger

    2006-01-01

    Lithostratigraphic analyses of a sub-annually laminated core from Ranu Lamongan, a maar lake on the island of Java, document\\u000a considerable changes in the lake’s chemistry and water balance over the past ca. 800 calendar years. Composition of the dark\\u000a (clastics) and light (diatoms and\\/or calcium carbonate minerals) couplets suggests that these laminations form in response\\u000a to seasonal changes in rainfall

  18. Honeycomb-laminate composite structure

    NASA Technical Reports Server (NTRS)

    Gilwee, W. J., Jr.; Parker, J. A. (inventors)

    1977-01-01

    A honeycomb-laminate composite structure was comprised of: (1) a cellular core of a polyquinoxaline foam in a honeycomb structure, and (2) a layer of a noncombustible fibrous material impregnated with a polyimide resin laminated on the cellular core. A process for producing the honeycomb-laminate composite structure and articles containing the honeycomb-laminate composite structure is described.

  19. Diatom DNA as historical information

    Microsoft Academic Search

    K. R. Stoof; L. S. Epp; M. H. Trauth; R. Tiedemann

    2009-01-01

    This survey is about the reconstruction of paleo environmental conditions in East Africa using recent and historic lakes sediments of shallow lakes in Kenya. This interdisciplinary approach combines the molecular analysis of ancient diatom DNA and the morphological analysis of diatom assemblages of short sediment cores to reveal the potential of molecular genetics in geosciences. This study comprises the investigation

  20. Diatom DNA as historical information

    NASA Astrophysics Data System (ADS)

    Stoof, K. R.; Epp, L. S.; Trauth, M. H.; Tiedemann, R.

    2009-04-01

    This survey is about the reconstruction of paleo environmental conditions in East Africa using recent and historic lakes sediments of shallow lakes in Kenya. This interdisciplinary approach combines the molecular analysis of ancient diatom DNA and the morphological analysis of diatom assemblages of short sediment cores to reveal the potential of molecular genetics in geosciences. This study comprises the investigation of two short sediment cores from Lake Naivasha (Kenya) taken in 2007, covering a stretch of ca. 80 years. Several sediment slices were analysed by molecular methods that concludes in species identification based on DNA fragments. Therefore total DNA was extracted and applied to a diatom DNA specific PCR amplifying a gene fragment that is frequently used for species identification. After cloning PCR products, clones were sequenced, sequences from different diatom species were analysed. As a comparison permanent slides were prepared for each sediment sample for counting diatom valves. The results suggest that DNA damage, perhaps species depended, and specific factors of PCR contribute to an overhang of two dominant diatom species (Aulacoseira ambigua and Aulacoseira granulata) represented by the molecular approach whereas rare species seen by light microscopy are not yet identifiable with molecular methods. Moreover changes in diatom assemblages and the reconstructed conductivity indicate a decrease of lake level around 1940. This shift seems to be also represented in the molecular approach as a decrease in the amount of diverse diatom DNA sequences found, what is probably caused by worse DNA preservation conditions at that time.

  1. 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)

  2. Biomarker evidence of Holocene climate and cryosphere variability: results from a 171m, annually laminated, sediment core from the Adélie coast, Antarctica (IODP Expedition 318)

    NASA Astrophysics Data System (ADS)

    Bendle, J. A.; Seki, O.; Kawamura, K.; Willmott, V.; Schouten, S.; Sangiorgi, F.; McKay, R.; Riesselman, C. R.; Dunbar, R. B.

    2012-12-01

    The Southern Ocean remains the least studied region on Earth with respect to Holocene climate variability. The few Antarctic proximal marine sedimentary records available tend to be short, low resolution, and discontinuous. However, sediments recently recovered from the Adélie drift during IODP Expedition 318 present a new opportunity to study East Antarctic Holocene climatic evolution, at a resolution that facilitates direct comparison with ice-cores. Expedition 318 recovered 171m of Holocene laminated diatom ooze from site U1357B. The sediments represent continuous Holocene accumulation up to the present day (based on 89 AMS 14C dates) and are characterised by 2-6cm thick, light/dark laminae couplets, interpreted as seasonal biogenic production and accumulation events. We present the results of initial biomarker analyses: fatty acid ?D and TEX86 measurements on lipid extracts from paired light/dark laminae throughout the Holocene. The C18 fatty acid is assumed to represent an integrated signal from the algal precursors and thus surface water conditions. The ?DC18-FA values show no consistent offset between the light and dark laminae, and values become isotopically heavier on average through the Holocene (ca. -220 to 140‰), in line with declining insolation at 65°S. Superimposed on this trend are millennial scale isotopic excursions of ca. 20 to 60‰, including a clear excursion coeval with an increase in grain size in U1356B and the late Holocene climate 'optimum' between 6 and 3 kyr, inferred from East Antarctic ice-cores. ?DC18-FA shows no clear relationship with TEXL86 sea-surface temperature estimates, which display pronounced early variability and relative warmth from 11.2 to 10.4 ka (0 to 6.5 °C, average ca. 3.5 °C), but almost no change after 10.4 ka, as cold, stable SSTs (average ca. 2 °C) persist through the rest of the Holocene. We explore the potential controls on the ?DC18-FA record and suggest the influence of isotopically depleted meltwater from the proximal ice-sheet (additive to a salinity effect) and/or upwelling could account for the millennial scale variability. The next steps are to ground-truth the proxies in this unique archive and to exploit the paleoclimatic information encoded in the abundant algal sterol compounds, the higher plant waxes and to apply compound-specific ?13C as well as additional ?D measurements.

  3. 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.

  4. 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.

  5. Lamination cooling system formation method

    SciTech Connect

    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.

  6. 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.

  7. Southern Ocean giant diatom mat deposits: markers of Pleistocene Antarctic Polar Front migration.

    NASA Astrophysics Data System (ADS)

    Kemp, A. E.; Grigorov, I.; Pearce, R. B.

    2006-12-01

    The Southern Ocean is a critical location for the biogeochemical cycling of silica and beneath its waters a sedimentary biogenic silica belt has formed. This sediment lies under and to the south of the present location of the Antarctic Polar Front which acts as a critical biogeochemical divider. The sediments recovered from ODP Sites 1091, 1093 and 1094 represent the only deep piston-cored record from this important zone. Within these sequences, that were deposited at the highest sustained pelagic accumulation rates ever recorded, giant Thalassiothrix diatom mat deposits occur intermittently. Following evidence from analogous diatom concentrations and recent oceanographic surveys in the Southern Ocean, the peak fluxes of Thalassiothrix diatoms are thought to have occurred beneath frontal zones such that these distinctive sediments may be used as a paleo-front indicators. Analysis of the occurrence of laminated diatom mat deposits from the above sites shows that a major southward migration in frontal position was associated with the Mid Pleistocene Transition. Higher frequency changes track the migration of the frontal region through glacial-interglacial cycles. Periods lacking diatom mat deposits at any site may represent periods of prolonged frontal instability.

  8. Laminates and reinforced metals

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1980-01-01

    A selective review is presented of the state of the art of metallic laminates and fiber reinforced metals called metallic matrix laminates (MMLs). Design and analysis procedures that are used for, and typical structural components that have been made from MMLs are emphasized. Selected MMLs, constituent materials, typical material properties and fabrication procedures are briefly described, including hybrids and superhybrids. Advantages, disadvantages, and special considerations required during design, analysis, and fabrication of MMLs are examined. Tabular and graphical data are included to illustrate key aspects of MMLs. Appropriate references are cited to provide a selective bibliography of a rapidly expanding and very promising research and development field.

  9. Transparent polymeric laminates

    NASA Technical Reports Server (NTRS)

    Parker, J. A.; Fohlen, G. M.; Sawko, P. M.

    1973-01-01

    Laminate prepared from epoxy-boroxine and phenolphthalein polycarbonate has high mechanical strength at elevated temperature and is resistant to impact, fire, and high-energy thermal radiation. Polycarbonate is prepared by reaction of phenolphthalein with phosgene in presence of amine catalyst and immiscible organic solvent phase.

  10. Renaissance in diatomic spectroscopy

    NASA Astrophysics Data System (ADS)

    Tiemann, Eberhard; Knöckel, Horst

    2013-07-01

    New technological developments resulted in several periods of renaissances of spectroscopy, the period on microwaves and later the period with lasers, and led to developments of new models for description of observations, thus to understanding the underlying physics. Today, the exciting period of cold molecules has started and demands for new data from molecular spectroscopy and completion in their modeling. This contribution will describe the status of understanding before the era of "cold molecules" and note open questions when entering the field of cold molecules. Because large varieties of cold molecules are studied, like deeply bound (about 1eV) or very weakly bound (less than 10-7 eV) ones, the spectroscopic tools and the theoretical descriptions have to be largely extended. We will describe recent success regarding different molecules of diatomic alkaliand alkaline-earth atoms as examples and will show how to use the often huge body of spectroscopic data for obtaining predictions for optimal paths to produce ultra cold molecules in a desired molecular state. It is very exciting to combine the results of spectroscopy and of studies of ultra cold ensembles which are influenced by their atom-to-molecule changeover. This allows already to complete the understanding of the electronic structure of atom pairs from infinite internuclear separation down to the range of strongly overlapping electronic distribution in some cases (e.g. KRb or KCs). However, enhanced effort is required for describing quantitatively the discoveries, already published or expected, like a contribution to the field hunting for signatures of time dependence of fundamental constants. For molecules with their rotational and vibrational motion the ratio of electron mass-to-nuclear mass as a fundamental constant shows up as an obvious attraction for spectroscopic studies.

  11. Teen Moon: Moon Ooze

    NSDL National Science Digital Library

    Lunar and Planetary Institute

    2010-01-01

    In this activity, learners model how the Moon's volcanic period reshaped its earlier features. Learners consider that the broad, shallow impact basins--which had formed earlier while it was a "kid Moon"--contained cracks through which magma seeped up. A plate in which slits have been cut is used to represent an impact basin and a dish of red-colored water is used to represent the pockets of magma within the Moon's upper layers. When the model impact basin is pressed into the magma, "lava" fills in the low areas through the same process that produced the dark patches, or maria, on the Moon. Learners may examine a type of Earth rock (named basalt) that is also found on the Moon and that would have been shaped by the processes explored here. This activity investigates the Moon's "teen years," when it was one to three billion years old.

    This activity station is part of a sequence of stations that can be set up to help learners trace the Moon's 4.5-billion-year history from "infancy" to the imagined future. Learners tie together major events in the Moon's geologic history as a series of comic panels in their Marvel Moon comic books.

  12. 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.

  13. 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.

  14. 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....

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. Do lamin A and lamin C have unique roles?

    PubMed

    Al-Saaidi, Rasha; Bross, Peter

    2015-03-01

    The A-type lamins, lamin A and lamin C, generated from a single gene, LMNA, are major structural components of the nuclear lamina. The two alternative splice products have mostly been studied together because they have been considered to be interchangeable. However, several lines of evidence indicate that in spite of being generated from the same gene and having high similarities in their primary sequences, the two isoforms are not equivalent in different biological aspects in both health and disease. The key question is whether they have both overlapping and unique functions and whether they are distinctly regulated. Based on the so far available experimental evidence, lamin A appears to be the most regulated A-type isoform during development, aging, and disease which indicates that lamin A is implicated in many different biological aspects and may have a greater repertoire of specialized functions than lamin C. The aim of this review is to point out differences between the two major LMNA splice variants and the consequences of these differences on their functions. This may guide further research and be of prime importance for the understanding of the pathogenesis of LMNA mutations. PMID:25283634

  20. Rotational Relaxation in Nonpolar Diatomic Gases

    Microsoft Academic Search

    John A. Lordi; Robert E. Mates

    1970-01-01

    The rotational-translational energy transfer in collisions between homonuclear diatomic molecules and the rotational relaxation time in diatomic gases have been investigated classically. Using Parker's model for the intermolecular potential, numerical solutions were obtained for the rotational-energy transfer in individual collisions. The method of solution for the collision trajectories has been combined with a Monte Carlo integration procedure to evaluate the

  1. Diatom Seasonal Abundance, Assemblages and Lipid Biomarkers: Towards a More Robust Reconstruction of Diatom Paleoproductivity

    NASA Astrophysics Data System (ADS)

    Santos, C.; Zuniga, D.; Hefter, J.; Frójan, M.; Salgueiro, E.; Castro, C. G.; Figueiras, F.; Schefuß, E.; Mollenhauer, G.; Abrantes, F. F. G.

    2014-12-01

    Diatoms are the dominant phytoplankton class in coastal upwelling systems, accounting for a large proportion of global primary production. Their frustules preserved in sediments are powerful paleoceanographic and paleoproductivity proxies. However, despite high diatom abundance in the water column, they are frequently affected by dissolution and their sedimentary record is discontinuous. A more robust reconstruction independent of preservation characteristics in the sediments would thus be desirable. Lipid biomarkers have a specific structure that might remain intact in the sediments and may be better preserved under conditions corrosive to diatom frustules. This research aims to investigate the organic imprint of upwelling-related diatom species, which may allow the reconstruction of past primary productivity in areas where diatoms are not preserved in the sediments. To better understand the preservation and chemical signature of diatoms in the sedimentary record, we are studying diatom abundance, assemblages and lipid biomarkers in samples from the water column, sediment traps, surface sediments and diatom cultures recovered at the Iberian Margin. This study aims 1) to understand the present-day seasonal abundance and diversity of diatoms, their relation to the hydrographic conditions, along with their transfer/preservation pathways into the sediments; 2) to identify the major groups of lipid biomarkers related with upwelling diatom species in this area. Diatom abundances and assemblages observed in the water column and sediment traps evidence seasonal primary productivity. Sediment traps and surface sediment samples are dominated by Leptocylindrus spp. and Chaetoceros spp. resting spores, suggesting these genera as productivity tracers. Preliminary results of the biomarkers study show that sterols, known to be one of the major groups of biomarkers related to diatoms, occur in different composition and concentration in the analyzed diatom cultures, water column and sediment trap samples. Others known diatom related lipid biomarkers, namely highly branched isoprenoids and long - chain diols, are also being investigated.

  2. 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.

  3. Overview of current laminitis research.

    PubMed

    Eades, Susan C

    2010-04-01

    All cases of laminitis are characterized by failure of the attachment of the epidermal cells of the epidermal laminae to the underlying basement membrane of the dermal laminae despite the diversity of diseases that underlie the syndrome. The preponderance of evidence supports roles for inflammation, metabolic derangement, endothelial and venous dysfunction, and matrix degradation as causes of laminitis. Inflammation, oxidant stress, and matrix degradation may be factors common to each of these mechanisms that lead to the laminar damage of laminitis. The understanding of the pathophysiology and progression of the disease is incomplete, and this limits efforts to prevent and treat this devastating disease successfully. However, scientific investigations are occurring at a phenomenal rate and shedding light on the pathophysiologic events involved with laminitis. PMID:20381735

  4. 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...

  5. University of Miami Undergraduate Marine and Atmospheric Science Program August 2013 ALL THE "OOZE" THAT'S FIT TO PRINT -ON THE WEB AT: http://www.rsmas.miami.edu/undergrad

    E-print Network

    Miami, University of

    University of Miami Undergraduate Marine and Atmospheric Science Program August 2013 ALL THE "OOZE" THAT'S FIT TO PRINT - ON THE WEB AT: http://www.rsmas.miami.edu/undergrad We welcome our new is (305) 284-2180. Our office email is marsci@miami.edu. OFFICE HOURS ARE 8:30 AM ­ 5:00 PM, Monday

  6. Risk factors for equine laminitis

    E-print Network

    Polzer, John Patrick

    1995-01-01

    : Epidemiology RISK FACTORS FOR EQUINE LAMINITIS A Thesis by JOHN PATRICK POLZER Submitted to Texas A8cM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Margaret Slater... (Chair of Co i ee) James Calvin (Me be Stuart Shalat (Member) Gerald Bratton (Head of Department) December 1995 Major Subject: Epidemiology ABSTRACT Risk Factors for Equine Laminitis. (December 1995) John Patrick Polzer, B. S. , St. Norbert...

  7. Creep of laminated aluminum composites

    Microsoft Academic Search

    W. Moore; T. J. Davies

    1980-01-01

    The creep behavior of a laminate system consisting of alternate layers of pure aluminum and SAP (sintered aluminum powder)\\u000a sheet has been examined in the temperature range 323 to 473 K and in the stress range 35 to 68 MN m?2. It was observed that secondary creep strain in the laminates was greater than in elemental SAP; the secondary creep

  8. DDD: Dynamic Database for Diatomics

    NASA Technical Reports Server (NTRS)

    Schwenke, David

    2004-01-01

    We have developed as web-based database containing spectra of diatomic moiecuies. All data is computed from first principles, and if a user requests data for a molecule/ion that is not in the database, new calculations are automatically carried out on that species. Rotational, vibrational, and electronic transitions are included. Different levels of accuracy can be selected from qualitatively correct to the best calculations that can be carried out. The user can view and modify spectroscopic constants, view potential energy curves, download detailed high temperature linelists, or view synthetic spectra.

  9. Electronic spectroscopy of diatomic molecules

    NASA Technical Reports Server (NTRS)

    Partridge, Harry; Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.

    1994-01-01

    This article provides an overview of the principal computational approaches and their accuracy for the study of electronic spectroscopy of diatomic molecules. We include a number of examples from our work that illustrate the range of application. We show how full configuration interaction benchmark calculations were instrumental in improving the understanding of the computational requirements for obtaining accurate results for diatomic spectroscopy. With this understanding it is now possible to compute radiative lifetimes accurate to within 10% for systems involving first- and second-row atoms. We consider the determination of the infrared vibrational transition probabilities for the ground states of SiO and NO, based on a globally accurate dipole moment function. We show how we were able to assign the a(sup "5)II state of CO as the upper state in the recently observed emission bands of CO in an Ar matrix. We next discuss the assignment of the photoelectron detachment spectra of NO and the alkali oxide negative ions. We then present several examples illustrating the state-of-the-art in determining radiative lifetimes for valence-valence and valence-Rydberg transitions. We next compare the molecular spectroscopy of the valence isoelectronic B2, Al2, and AlB molecules. The final examples consider systems involving transition metal atoms, which illustrate the difficulty in describing states with different numbers of d electrons.

  10. A review of diatom ?18O in palaeoceanography

    NASA Astrophysics Data System (ADS)

    Swann, George E. A.; Leng, Melanie J.

    2009-03-01

    Measurements of diatom oxygen isotopes ( ?18O diatom) hold the potential to provide an important additional source of palaeoceanographic information in regions depleted in carbonates. However, despite analyses of ?18O diatom being carried out since the 1970s and the increasingly widespread use of ?18O diatom in palaeolimnology since the 1990s, to date only a handful of studies have applied ?18O diatom in marine reconstructions. Here the historical development and current state of affairs concerning the usage of ?18O diatom in palaeoceanography is reviewed. This includes a summary of: sample purification and analytical techniques for ?18O diatom; existing palaeoceanographic reconstructions with an emphasis on sites at which both diatoms and foraminifera have been analysed for ?18O; uncertainties associated with ?18O diatom including the presence of isotope vital effects and secondary isotope exchanges; a review of the current and future developments required to improve the reliability of ?18O diatom based reconstructions in palaeoceanography.

  11. 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.

  12. Both lamin A and lamin C mutations cause lamina instability as well as loss of internal nuclear lamin organization

    SciTech Connect

    Broers, Jos L.V. [Department of Molecular Cell Biology, Box 17, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 616, NL-6200 MD Maastricht (Netherlands) and Department of Biomedical Engineering, Biomechanics and Tissue Engineering Eindhoven University of Technology (Netherlands)]. E-mail: jos.broers@molcelb.unimaas.nl; Kuijpers, H.J.H. [Department of Molecular Cell Biology, Box 17, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 616, NL-6200 MD Maastricht (Netherlands); Oestlund, C. [Departments of Medicine and of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY 10027 (United States); Worman, H.J. [Departments of Medicine and of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY 10027 (United States); Endert, J. [Department of Molecular Cell Biology, Box 17, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 616, NL-6200 MD Maastricht (Netherlands); Ramaekers, F.C.S. [Department of Molecular Cell Biology, Box 17, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 616, NL-6200 MD Maastricht (Netherlands)

    2005-04-01

    We have applied the fluorescence loss of intensity after photobleaching (FLIP) technique to study the molecular dynamics and organization of nuclear lamin proteins in cell lines stably transfected with green fluorescent protein (GFP)-tagged A-type lamin cDNA. Normal lamin A and C proteins show abundant decoration of the inner layer of the nuclear membrane, the nuclear lamina, and a generally diffuse localization in the nuclear interior. Bleaching studies revealed that, while the GFP-tagged lamins in the lamina were virtually immobile, the intranuclear fraction of these molecules was partially mobile. Intranuclear lamin C was significantly more mobile than intranuclear lamina A. In search of a structural cause for the variety of inherited diseases caused by A-type lamin mutations, we have studied the molecular organization of GFP-tagged lamin A and lamin C mutants R453W and R386K, found in Emery-Dreifuss muscular dystrophy (EDMD), and lamin A and lamin C mutant R482W, found in patients with Dunnigan-type familial partial lipodystrophy (FPLD). In all mutants, a prominent increase in lamin mobility was observed, indicating loss of structural stability of lamin polymers, both at the perinuclear lamina and in the intranuclear lamin organization. While the lamin rod domain mutant showed overall increased mobility, the tail domain mutants showed mainly intranuclear destabilization, possibly as a result of loss of interaction with chromatin. Decreased stability of lamin mutant polymers was confirmed by flow cytometric analyses and immunoblotting of nuclear extracts. Our findings suggest a loss of function of A-type lamin mutant proteins in the organization of intranuclear chromatin and predict the loss of gene regulatory function in laminopathies.

  13. Effects of pesticides on freshwater diatoms.

    PubMed

    Debenest, Timothée; Silvestre, Jérôme; Coste, Michel; Pinelli, Eric

    2010-01-01

    The study of pesticide effects on algae, and diatoms in particular, was focused on photosynthesis and biomass growth disturbances. Few studies have been performed to investigate the effects of these toxic agents on intracellular structures of diatom cells. Nuclear alterations and cell wall abnormalities were reported for diatoms exposed to toxic compounds. Nevertheless, the cellular mechanisms implicated in the development of such alterations and abnormalities remain unclear. Sensitivity to pesticides is known to be quite different among different diatom species. Eutrophic and small species are recognized for their tolerance to pesticides exposure. More pronounced cell defenses against oxidative stress may explain this absence of sensitivity in species of smaller physical size. Notwithstanding, on the whole, explaining the rationale behind tolerance variations among species has been quite difficult, thus far. In this context, the understanding of intracellular toxicity in diatoms and the relation between these intracellular effects and the disturbance of species composition in communities represent a key target for further research. The original community species structure determines the response of a diatom community to toxic agent exposure. Diatom communities that have species capable of switching from autotrophic to heterotrophic modes, when photosynthesis is inhibited (e.g., after pesticide exposure), can continue to grow, even in the presence of high pesticide pollution. How diatoms respond to toxic stress, and the degree to which they respond, also depends on cell and community health, on ecological interactions with other organisms, and on general environmental conditions. The general structural parameters of diatom communities (biomass, global cell density) are less sensitive to pesticide effects than are the specific structural parameters of the unicellular organisms themselves (cell density by species, species composition). For benthic species, biofilm development and grazing on this matrix as a source of food for invertebrates and fishes may also modify the response of diatom communities. Environmental parameters (light exposure, nutrient concentrations, and hydraulic conditions) affect, and often interfere with, the response of diatoms to pesticides. Therefore, the complexity of aquatic ecosystems and the complexity of pesticide to easily detect the effects of such pollutants on diatoms. Clearly more research will be required to address this problem. PMID:19957117

  14. Interphase phosphorylation of lamin A

    PubMed Central

    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.

    2014-01-01

    ABSTRACT 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

  15. Dynamics of laminated write elements

    NASA Astrophysics Data System (ADS)

    Heinonen, Olle; Nazarov, Alexey; Plumer, Martin L.

    2006-04-01

    One concern as storage technology moves to perpendicular recording is the remnant state of the writer top pole. In principal, a remnant state with a substantial magnetization density perpendicular to the recording medium can lead to the unwanted erasure of data. Also, it is desirable to have the writer reach a nonerasing remnant state as quickly as possible. One technique to reduce the magnetization in the remnant state is to laminate the pole tip with some nonmagnetic material [Y. Satoh, A. Ohtsubo, and Y. Shimada, IEEE Trans. Magn. 21, 1551 (1985); S. Wang et al., IEEE Trans. Magn. 30, 3897 (1994)]. We have performed fully micromagnetic simulations of write elements with eight, five, four, and two laminates coupled antiferromagnetically. Results are presented for recording fields, as well as for the decay of the magnetization to a remnant state. The two- and four-laminate write elements typically have a vortex induced in the pole tip, and this vortex tends to survive, even in the remnant state. This can give rise both to a slow decay as well as large remnant fields from the out-of-plane magnetization in the vortex. On the other hand, the magnetization of the eight-laminate pole tip decays by ``scissoring'' of the magnetization in the laminates, with a faster decay to the remnant state. However, locally large divergences of the magnetization density can give rise to ``hot spots'' with relatively large remnant fields.

  16. A lamin in lower eukaryotes?

    PubMed Central

    Batsios, Petros; Peter, Tatjana; Baumann, Otto; Stick, Reimer; Meyer, Irene; Gräf, Ralph

    2012-01-01

    Lamins are the major components of the nuclear lamina and serve not only as a mechanical support, but are also involved in chromatin organization, epigenetic regulation, transcription and mitotic events. Despite these universal tasks, lamins have so far been found only in metazoans. Yet, recently we have identified Dictyostelium NE81 as the first lamin-like protein in a lower eukaryote. Based on the current knowledge, we draw a model for nuclear envelope organization in Dictyostelium in this Extra View and we review the experimental data that justified this classification. Furthermore we provide unpublished data underscoring the requirement of posttranslational CaaX-box processing for proper protein localization at the nuclear envelope. Sequence comparison of NE81 sequences from four Dictyostelia with bona fide lamins illustrates the evolutional relationship between these proteins. Under certain conditions these usually unicellular social amoebae congregate to form a multicellular body. We propose that the evolution of the lamin-like NE81 went along with the invention of multicellularity. PMID:22572958

  17. 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

  18. Nuclear lamins: building blocks of nuclear architecture

    E-print Network

    Goldman, Robert D.

    Biological Laboratory, Woods Hole, Massachusetts 02543, USA Nuclear lamins were initially identified is expressed in all cells, except for mature sperm (Liu et al. 2000). Dro- sophila melanogaster has two lamin

  19. Impedances of Laminated Vacuum Chambers

    SciTech Connect

    Burov, A.; Lebedev, V.; /Fermilab

    2011-06-22

    First publications on impedance of laminated vacuum chambers are related to early 70s: those are of S. C. Snowdon [1] and of A. G. Ruggiero [2]; fifteen years later, a revision paper of R. Gluckstern appeared [3]. All the publications were presented as Fermilab preprints, and there is no surprise in that: the Fermilab Booster has its laminated magnets open to the beam. Being in a reasonable mutual agreement, these publications were all devoted to the longitudinal impedance of round vacuum chambers. The transverse impedance and the flat geometry case were addressed in more recent paper of K. Y. Ng [4]. The latest calculations of A. Macridin et al. [5] revealed some disagreement with Ref. [4]; this fact stimulated us to get our own results on that matter. Longitudinal and transverse impendances are derived for round and flat laminated vacuum chambers. Results of this paper agree with Ref. [5].

  20. Sheet steel lamination for rapid manufacturing

    Microsoft Academic Search

    T Obikawa; M Yoshino; J Shinozuka

    1999-01-01

    A layer manufacturing method using thin sheet steel has been developed for the direct and rapid manufacturing of laminated steel products with high accuracy. The laminated steel products were manufactured by repeating two principal processes: (1) welding of thin sheet steels in a layer-by-layer fashion for heaping up a laminated workpiece; and (2) cutting of a CAD model cross section

  1. 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.

  2. OPTIMIZED CURING OF THICK SECTION COMPOSITE LAMINATES

    Microsoft Academic Search

    Z. L. Yang

    2001-01-01

    Conventional autoclave curing cycles for thermosetting composite laminates are generally derived from trial-and-error experimentation. Cure cycles are readily available for thin composite laminates. However, developing cure cycles for thick section laminates is time consuming and hence, costly. In addition, one cannot be sure that a selected cycle will be optimum if it is based on a conventional method. This paper

  3. Machining of fiber-reinforced composite laminates

    Microsoft Academic Search

    Myong-Shik Won

    1999-01-01

    As fiber-reinforced composite laminates are becoming considerably popular in a wide range of applications, the necessity for machining such materials is increasing rapidly. Due to their microscopical inhomogeneity, anisotropy, and highly abrasive nature, composite laminates exhibit some peculiar types of machining damage. Consequently, the machining of composite laminates requires a different approach from that used for metals and offers a

  4. Jute and glass fibre hybrid laminates

    Microsoft Academic Search

    R. A. Clark; M. P. Ansell

    1986-01-01

    Hybrid laminates have been fabricated from randomly oriented jute fibre mats and woven glass fabrics with a common polyster resin matrix. Hand lay up techniques were used to simulate practical production methods in the field. A variety of laminate constructions were mechanically tested and some laminates were in addition assessed for environmental stability. Modified rule of mixtures expressions successfully predicted

  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. Last Century Patterns of Surface Ocean and Diatom Variability in the Southern California Current

    NASA Astrophysics Data System (ADS)

    Esparza, M.; Herguera, J.; Lange, C. B.

    2006-12-01

    A time series reconstruction for the last 100 years of the variability of diatoms from laminated sediments off the southern Baja California margin shows the sensitivity of this phytoplankton group to oceanographic variability in the California Current on different timescales. Here we show that cool (warm) years are associated with higher (lower) diatom accumulation values, a proxy for their export production from the water column to the seafloor. There is a clear direction in the changes of the opaline flora community structure throughout the past century that parallels the observed trend towards higher SSTs in the southern part of the California Current. The diatom succession is reflected in three types of assemblages that show a clear progression from cool spring to early summer bloom species in the earlier part of the century towards alternating cool California Current and warm subtropical waters during the mid-century, to subtropical and tropical assemblages reflecting more stratified oligotrophic conditions during the latter part of the last century. This association between opaline floral succession and the SST anomaly trend implies a long term change that cannot be explained by the same mechanisms that are commonly associated with the typical interannual or interdecadal oceanographic variability. A small group of diatom species appears to follow the periodic swings of the large scale Pacific Decadal Oscilation index. The Coscinodiscus argus/radiatus and Coscinodiscus decrescens/marginatus complexes, commonly found in the California Current waters, closely follow the inter- decadal variability patterns over the Pacific, although with a decreasing amplitude after the mid 1970s shift. We will further discuss the implications of both observations on the direction of the observed changes and the cyclicity in the opaline floral record in terms of the oceanographic variability in the southern boundary of the California Current.

  7. 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

  8. The diatomic dication PO2+.

    PubMed

    Révész, Agnes; Sztáray, Bálint; Schröder, Detlef; Franzreb, Klaus; Fiser, Jirí; Price, Stephen D; Roithová, Jana

    2009-08-01

    The diatomic dication PO(2+) has been generated by the sputtering of surface-oxidized InP wafers and by electron ionization of gaseous trimethyl phosphate. According to ab initio calculations, the dication PO(2+) is metastable with respect to dissociation into P(+) + O(+), and the calculated ionization energy of the PO(+) monocation to form the dicationic species is ca. 22.6 eV. The potential energy functions for the ground state and twelve low-lying excited electronic states of the PO(2+) dication have been calculated using high-level ab initio methods with adiabatic excitation energies of PO(2+), spectroscopic constants and the ionization energies of PO and PO(+) being determined. Upon collision with xenon, electron transfer to PO(2+) takes place to form the PO(+) monocation together with a small amount of dissociative electron transfer to form P(+). Upon collisions of PO(2+) with deuterium, charge separation is accompanied by a bond-forming reaction to yield monocationic POD(+). PMID:19606329

  9. 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.

  10. Diatom-based reconstruction of the Lake Czechowskie trophy status in the last 2000 years (Tuchola Forest, Northern Poland)

    NASA Astrophysics Data System (ADS)

    Rzodkiewicz, Monika; Hübener, Thomas; Ott, Florian; Kramkowski, Mateusz; Obremska, Milena; S?owi?ski, Micha?; Zawiska, Izabela; B?aszkiewicz, Miros?aw; Brauer, Achim

    2015-04-01

    Lakes ecosystems are very sensitive to climate and environment fluctuation. In lake sediments there are preserved remains of plant and animals that lived in the lake and its surroundings in the past. In paleolimnological research we analyse the species composition of the assemblages preserved in the sediments and on this base reconstruct past environment changes (climate changes). One of the most commonly used bio-proxy for reconstruction of lake development are subfossil diatoms. Diatoms are commonly used to reconstruct such environment parameters as: pH, nutrient status, salinity or temperature. In our study we analysed the sediments of Lake Czechowskie, which is located in the northern part of the Tuchola Forest region (Northern Poland). Lacustrine sediments of this lake are laminated and therefore are unique archive to reconstruct climate and environmental changes in Northern Polish Lowland. In this research we focused on the last 2000 years and with high resolution analyzed diatoms, pollen and sediment geochemistry. The core chronology is based varve counting, 14C AMS dating of terrestrial macro remains, 137Cs activity measurement. Diatoms communities during the last 2000 years were rich and mostly very well preserved. A characteristic feature of those communities is the dominance of typically planktonic species of the spring phytoplankton, as the oligo to mesotraphent Cyclotella comensis but also the eutraphent Stephanodiscus parvus. We also aimed at quantitative reconstruction of the pH and eutrophication(TP) using diatom-based transfer functions in order to identify reference conditions for the Lake Czechowskie. Transfer function are based on the assumption that the modern biological proxies, which ecological requirements are known, can be used to quantitative reconstructions of the past changes. This study is a contribution to the Virtual Institute ICLEA (Integrated Climate and Landscape Evolution Analysis) funded by the Helmholtz Association. The research was supported by the National Science Centre Poland (grant NCN 2011/01/B/ST10/07367).

  11. High-resolution diatom records of climate and hydrological variability over the last two millennia along coastal British Columbia (Canada)

    NASA Astrophysics Data System (ADS)

    Hay, M. B.; Pienitz, R.; Dallimore, A.; Calvert, S. E.; Thomson, R.; Baumgartner, T. R.; Enkin, R.; Cooke, K.

    2010-12-01

    High-resolution ocean archives covering the last 2000 years are essential for assessments of modern-day and future climate, and better understanding of the response of marine environments to global change. Sedimentary records recovered from coastal locations yield information on both terrestrial and marine conditions and permit detailed reconstructions of past climatic and environmental variability. Anoxic basins within coastal inlets favour the preservation of varved (annually laminated) sediment records, permitting high-resolution analysis of past environmental change. Although a number of marine records have been recovered from the west coast of British Columbia, Canada, few studies have focused on conditions over the last 2000 years. Here we present siliceous microfossil (diatom) records from a pair of anoxic fjords located along the southwestern coast of British Columbia. The record from Effingham Inlet (Vancouver Island) represents 1500 years of regional climate and hydrological variability at sub-decadal resolution. Fossil diatom assemblages from the inlet are sensitive to changes in freshwater inputs from nearby rivers and creeks. Increased freshwater discharge into the inlet between 825 and 925 AD, 1000 and 1325 AD and again from ca. 1550 to 1850 AD favoured deep water renewal events in the fjord. The timing of these periods correlates with reconstructed periods of cooler and moister conditions and a negative Pacific Decadal Oscillation (PDO) index in the North Pacific. A second site in Frederick Sound (Seymour-Belize inlet complex) represents a preliminary evaluation of the sensitivity of fossil diatom assemblages to regional climate variability in this inlet over the last two millennia. Analysis of the diatom assemblages between 1650 and 550 AD from Frederick Sound suggests that diatom assemblages within this basin are sensitive to changes in regional climate, matching the conditions observed within the more southern Effingham Inlet. Differences between the two records also highlight the critical importance of site selection for the reconstruction of environmental change over the last 2000 years.

  12. 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.

  13. Designer diatom episomes delivered by bacterial conjugation

    PubMed Central

    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

  14. Plastic Laminate Pulsed Power Development

    SciTech Connect

    ALEXANDER,JEFF A.; SHOPE,STEVEN L.; PATE,RONALD C.; RINEHART,LARRY F.; JOJOLA,JOHN M.; RUEBUSH,MITCHELL H.; CROWE,WAYNE; LUNDSTROM,J.; SMITH,T.; ZAGAR,D.; PRESTWICH,K.

    2000-09-01

    The desire to move high-energy Pulsed Power systems from the laboratory to practical field systems requires the development of compact lightweight drivers. This paper concerns an effort to develop such a system based on a plastic laminate strip Blumlein as the final pulseshaping stage for a 600 kV, 50ns, 5-ohm driver. A lifetime and breakdown study conducted with small-area samples identified Kapton sheet impregnated with Propylene Carbonate as the best material combination of those evaluated. The program has successfully demonstrated techniques for folding large area systems into compact geometry's and vacuum impregnating the laminate in the folded systems. The major operational challenges encountered revolve around edge grading and low inductance, low impedance switching. The design iterations and lessons learned are discussed. A multistage prototype testing program has demonstrated 600kV operation on a short 6ns line. Full-scale prototypes are currently undergoing development and testing.

  15. 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

  16. 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.

  17. Compression-Failure Mechanisms in Composite Laminates

    NASA Technical Reports Server (NTRS)

    Shuart, M. J.; Williams, J. G.; Cooper, P. A.

    1986-01-01

    Failure mechanisms observed using transparent fiberglass/epoxy birefringent materials. Technique based on use of transparent fiberglass/epoxy birefringent material. Transparency allows visual observation of location of initial laminate failure and of subsequent failure propagation; birefringence allows laminate stress distribution to be observed during test and also after test if permanent residual stresses occur. Nondestructive technique developed to observe failure as it develops and as propagates within laminate.

  18. 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

  19. 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.

  20. 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.

  1. High-resolution past environmental reconstruction in East Asia using annually laminated lake sediments of Lake Megata in northeastern Japan

    NASA Astrophysics Data System (ADS)

    Yamada, K.; Gotanda, K.; Yonenobu, H.; Shinozuka, Y.; Kitagawa, J.; Makohonienko, M.; Schwab, M.; Haraguchi, T.; Yasuda, Y.

    2007-12-01

    37 m-long non-glacial varved sequences were taken from Ichi-no-Megata maar in Oga Peninsula, Akita, northern part of Japan. Ichi-no-Megata maar occupies 0.25 km2 with a maximum water depth of ca. 45.1 m. The shape of lake is a kettle-type basin and the deepest bottom basin is very flat. We took core samples (named IMG06 core) at the center of the lake in November to December in 2006. In order to take completely continuous maar sediment, we drilled three holes and take every sample from each hole which apart only few meters. In this drilling campaign, we can 37 m-long continuous maar sediment except thick volcanic deposits from 26.5 to 31.7m in core. The sedimentological feature of IMG06 core is dominated by thin lamination clay/silt from most top part up to 37 m with turbidites characterized upward fining structure. The SEM image observation of lamination reveals that sponge-like lamina consists of diatom assemblage against dark colored lamina consists of mixture of detritus minerals, clay minerals, and diatom. It means sponge-like lamina deposits during spring season, and later one deposits during another three seasons, and then these thin lamination of IMG06 core could be identified as annual lamination (varves). This interpretation is supported by the correlation of historic event as earthquake and tunnel construction. In this IMG06 core, six volcanic ashes are found and we have also analyzed radiocarbon dating from 38 horizons of the core to use leaf and seeds inter-bedded varves. As the results, the IMG06 core covers from 25,000 to 4,000 14C yr BP with stable sedimentation rates (0.71mm/year).

  2. Rotational Relaxation of Homonuclear Diatomic Molecules

    Microsoft Academic Search

    Carl Nyeland

    1967-01-01

    Through the use of Wang Chang and Uhlenbeck's theory of polyatomic gases, rotational relaxation times for homonuclear diatomic molecules have been calculated. The model adopted is that of two molecules rotating in the same plane which also serves as the collision plane. The intermolecular potential used is Parker's modification of the Morse potential, where the molecular orientations are taken into

  3. Bond forces and pressure in diatomic liquids

    Microsoft Academic Search

    J. Gao; J. H. Weiner

    1990-01-01

    Quantum-mechanical considerations indicate that a reasonable classical model for a diatomic system is one in which bond lengths are constant. Two types of such models may be distinguished: rigid models in which the constant length is imposed from the outset as a geometric constraint and flexible models in which the bond is represented by a stiff spring whose force constant

  4. Diatoms from the Shelton Mastodon Site

    Microsoft Academic Search

    E. F. Stoermer; J. P. Kociolek; J. Shoshani; C. Frisch

    1988-01-01

    A fairly diverse and abundant diatom flora is associated with remains of Mammut americanum at the Shelton Mastodon Site in northern Oakland County, Michigan. The most abundant elements of this flora are species commonly recorded from late-glacial deposits in North America and Europe. The nearest modern analogues of this flora are assemblages deposited in small lakes in the high arctic

  5. 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.

  6. Free vibration of initially stressed composite laminates

    Microsoft Academic Search

    R. Dhanaraj; Palaninathan

    1990-01-01

    The characteristics of fundamental modes of vibration of initially stressed composite laminated plates are presented in this paper. The semiloof finite element is used in this formulation. Angle-ply and cross-ply rectangular laminates with simply supported and clamped edge conditions have been analyzed for which results have not been reported in the literature earlier. The effect of using ``the same'' and

  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. Wrinkling behavior of laminated steel sheets

    Microsoft Academic Search

    H. S. Cheng; Jian Cao; H. Yao; S. D. Liu; Brad Kinsey

    2004-01-01

    Laminated steel sheets sandwiched with a polymer core are increasingly used for automotive applications to improve vehicle’s vibration-damping performance without adding additional weight. It has been observed that the laminated sheets are prone to wrinkling during stamping processes. Due to the significant difference in material properties between the polymer core and the skin steel, FEM prediction of the occurrence, the

  9. Analytical modelling of laminated composites

    NASA Technical Reports Server (NTRS)

    Kouri, Jeffrey V.; Atluri, Satya N.

    1991-01-01

    This paper presents a unique approach to the analysis of thick laminated composites by presenting two simple finite element methods. The first uses the predictor corrector technique to extend the simple Mindlin-type element to achieve greater accuracy, and the second develops a new least squares element which can approximate a C(1) continuous element. The least squares element has the capability to incorporate a simplified higher-order basis into a piecewise continuous displacement field creating an accurate, yet computationally simple, element. These two methods have the potential to significantly upgrade analysis methods with little additional computational cost.

  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. Effect of temperature on diatom volume, growth rate, and carbon and nitrogen content: Reconsidering some paradigms

    Microsoft Academic Search

    David J. S. Montagnes; Daniel J. Franklin

    2008-01-01

    We examined the response of diatoms to naturally experienced temperatures and tested these hypotheses: (1) diatoms follow the rule that organism size decreases with increasing temperature; (2) diatom growth rate follows a Q10-like response; (3) diatom carbon (C) and nitrogen (N) content per unit volume (V) decrease with increasing size, and changes in temperature affect this relationship; and (4) diatom

  12. The Different Function of Single Phosphorylation Sites of Drosophila melanogaster Lamin Dm and Lamin C

    PubMed Central

    Zaremba-Czogalla, Magdalena; Piekarowicz, Katarzyna; Wachowicz, Katarzyna; Kozio?, Katarzyna; Dubi?ska-Magiera, Magda; Rzepecki, Ryszard

    2012-01-01

    Lamins' functions are regulated by phosphorylation at specific sites but our understanding of the role of such modifications is practically limited to the function of cdc 2 (cdk1) kinase sites in depolymerization of the nuclear lamina during mitosis. In our study we used Drosophila lamin Dm (B-type) to examine the function of particular phosphorylation sites using pseudophosphorylated mutants mimicking single phosphorylation at experimentally confirmed in vivo phosphosites (S25E, S45E, T435E, S595E). We also analyzed lamin C (A-type) and its mutant S37E representing the N-terminal cdc2 (mitotic) site as well as lamin Dm R64H mutant as a control, non-polymerizing lamin. In the polymerization assay we could observe different effects of N-terminal cdc2 site pseudophosphorylation on A- and B-type lamins: lamin Dm S45E mutant was insoluble, in contrast to lamin C S37E. Lamin Dm T435E (C-terminal cdc2 site) and R64H were soluble in vitro. We also confirmed that none of the single phosphorylation site modifications affected the chromatin binding of lamin Dm, in contrast to the lamin C N-terminal cdc2 site. In vivo, all lamin Dm mutants were incorporated efficiently into the nuclear lamina in transfected Drosophila S2 and HeLa cells, although significant amounts of S45E and T435E were also located in cytoplasm. When farnesylation incompetent mutants were expressed in HeLa cells, lamin Dm T435E was cytoplasmic and showed higher mobility in FRAP assay. PMID:22393432

  13. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Microsoft Academic Search

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

    2012-01-01

    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

  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. Heteronuclear diatomics in diffuse and translucent clouds

    E-print Network

    Weselak, T

    2013-01-01

    Diffuse and translucent molecular clouds fill a vast majority of the interstellar space in the galactic disk being thus the most typical objects of the Interstellar Medium (ISM). Recent advances in observational techniques of modern optical and ultraviolet spectroscopy led to detection of many features of atomic and molecular origin in spectra of such clouds. Molecular spectra of heteronuclear diatomic molecules, ie. OH, OH+, CH CH+, CN, NH, CO play an important role in understanding chemistry and physical conditions in environments they do populate. A historical review of astronomical observations of interstellar molecules is presented. Recent results based on visual and ultraviolet observations of molecular features in spectra of reddened, early type OB-stars are presented and discussed. Appearance of vibrational-rotational spectra with observed transitions based on high-quality spectra, are also presented. Relations between column densities of heteronuclear diatomics (based on the recommended oscillator st...

  16. Laminitis and the equine metabolic syndrome.

    PubMed

    Johnson, Philip J; Wiedmeyer, Charles E; LaCarrubba, Alison; Ganjam, V K Seshu; Messer, Nat T

    2010-08-01

    Although much has been written about laminitis in the context of its association with inflammatory processes, recognition is growing that most cases of laminitis examined by veterinarians in private practice are those associated with pasture grazing, obesity, and insulin resistance (IR). The term 'endocrinopathic laminitis' has been adopted to classify the instances of laminitis in which the origin seems to be more strongly associated with an underlying endocrinopathy, such as either IR or the influence of corticosteroids. Results of a recent study suggest that obesity and IR represent the most common metabolic and endocrinopathic predispositions for laminitis in horses. IR also plays an important role in the pathogenesis of laminitis that develops when some horses or ponies are allowed to graze pastures at certain times of the year. The term equine metabolic syndrome (EMS) has been proposed as a label for horses whose clinical examination results (including both physical examination and laboratory testing) suggest heightened risk for developing laminitis as a result of underlying IR. PMID:20699172

  17. 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 one’s 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

  18. The Structure of the Diatomic Molecular Solids

    Microsoft Academic Search

    C. A. English; J. A. Venables

    1974-01-01

    A simple model of the low temperature phases of the diatomic molecular solids is examined. The model consists of molecules, interacting via a Lennard-Jones atom-atom potential and quadrupole-quadrupole interactions. The internal energy of any crystallographic structure (excluding thermal effects) can then be given in terms of two dimensionless parameters, which describe the deviation of the molecular shape from a sphere

  19. Systematic identification of pathological lamin A interactors.

    PubMed

    Dittmer, Travis A; Sahni, Nidhi; Kubben, Nard; Hill, David E; Vidal, Marc; Burgess, Rebecca C; Roukos, Vassilis; Misteli, Tom

    2014-05-01

    Laminopathies are a collection of phenotypically diverse diseases that include muscular dystrophies, cardiomyopathies, lipodystrophies, and premature aging syndromes. Laminopathies are caused by >300 distinct mutations in the LMNA gene, which encodes the nuclear intermediate filament proteins lamin A and C, two major architectural elements of the mammalian cell nucleus. The genotype-phenotype relationship and the basis for the pronounced tissue specificity of laminopathies are poorly understood. Here we seek to identify on a global scale lamin A-binding partners whose interaction is affected by disease-relevant LMNA mutations. In a screen of a human genome-wide ORFeome library, we identified and validated 337 lamin A-binding proteins. Testing them against 89 known lamin A disease mutations identified 50 disease-associated interactors. Association of progerin, the lamin A isoform responsible for the premature aging disorder Hutchinson-Gilford progeria syndrome, with its partners was largely mediated by farnesylation. Mapping of the interaction sites on lamin A identified the immunoglobulin G (IgG)-like domain as an interaction hotspot and demonstrated that lamin A variants, which destabilize the Ig-like domain, affect protein-protein interactions more globally than mutations of surface residues. Analysis of a set of LMNA mutations in a single residue, which result in three phenotypically distinct diseases, identified disease-specific interactors. The results represent a systematic map of disease-relevant lamin A interactors and suggest loss of tissue-specific lamin A interactions as a mechanism for the tissue-specific appearance of laminopathic phenotypes. PMID:24623722

  20. Characterization of impact damage in ARALL laminates

    NASA Astrophysics Data System (ADS)

    Sun, C. T.; Dicken, A.; Wu, H. F.

    Indentation tests have been performed to model the contact behavior between ARALL laminates and a steel ball. Subsequently, low-velocity impact testing was conducted to determine the failure modes due to impact. A sectioning technique has been used to examine impact damage in the laminate. The results show that the strength degradation in ARALL laminates resulting from impact depends on the fiber orientation. Strength in the transverse direction remains insensitive to impact damage, while in the fiber direction, the strength decreases as impact velocity increases beyond a certain range. Residual strength after impact can be determined solely from the permanent local indentation left by the impactor.

  1. Impact damage in composite laminates

    NASA Technical Reports Server (NTRS)

    Wang, Chung-Yue; Yew, Ching H.

    1990-01-01

    A low-velocity impact-damage model for quasi-symmetric graphite-fiber composite plates is presented. The distribution of damage in each layer of the plate was calculated by employing Di Sciuva's composite laminate theory together with Hashin's failure criterion for fiber-reinforced composites. The dynamic deformation of the target plate was represented by the lower vibrational modes of the plate. The principle of virtual work was applied in the formulation of the problem. In the analysis, the material was regarded as 'damaged' when its designed strength was reduced by the failure of its constituents. The constituent failures consisted of matrix crackings, fiber breakages, and delamination between layers. According to damage modes, the moduli of material in the damaged zone were reduced according to the failure criteria. The interaction between layers and its role in damage propagation were also studied.

  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. Free edge effects in laminated composites

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1989-01-01

    The fundamental mechanics of free-edge effects in laminated fiber-reinforced composites is examined, reviewing the results of recent experimental and analytical investigations. The derivation of the governing equations for the basic problem is outlined, including the equilibrium and mismatch conditions and the elasticity formulation, and experimental data on axial displacement and shear strain in angle-ply laminates are summarized. Numerical predictions of free-edge deformation and interlaminar and through-thickness stress distributions are presented for cross-ply, angle-ply, and quasi-isotropic laminates, and the mechanisms of edge damage and failure in angle-ply laminates are briefly characterized. Extensive diagrams, drawings, graphs, and photographs are provided.

  5. Static Behaviour of Laminated Composite Shells

    NASA Astrophysics Data System (ADS)

    Kuriakose, B.; Sathyabhama, L.; Valsarajan, K. V.

    2012-12-01

    With the advancement of aerospace engineering and the progress made in the allied industries, new forms of structural components having high strength-to-weight ratio have been developed. Fibre-reinforced laminate structures are one such type of construction. In the present study, linear behaviour of laminated composite shells under static loading is investigated using ANSYS, the finite element software, by varying the parameters such as laminate thickness, fibre orientation, stacking sequence, fibre strength and radius-to-thickness ratio. It has been observed that the deflection remains constant beyond four layers in the case of anti-symmetric arrangement and for the same angle of fibre orientation, deflection is not influenced by the lamination sequence. The non-dimensional deflection decreases with increase in material anisotropy and included angle, while it increases with increase in radius-to-thickness ratio.

  6. 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.

  7. Laminate Propellant Combustion (Review) 2. Theoretical Investigations

    Microsoft Academic Search

    R. P. Fitzgerald; M. Q. Brewster

    2006-01-01

    A review of theoretical research of the combustion of laminate propellants is given. The purpose and description of the simplification\\u000a of heterogeneous propellants through the use of constituent layers is detailed. This second of a two-part review describes:\\u000a 1) the development of knowledge of the deflagration of laminates through analytical and computational descriptions of many\\u000a different aspects of the overall

  8. Fatigue crack growth in aluminum laminate composites

    SciTech Connect

    Hoffman, P.B. [Columbian Chemicals Co., Swartz, LA (United States). Technology Center; Carpenter, R.D.; Gibeling, J.C. [Univ. of California, Davis, CA (United States). Div. of Materials Science and Engineering

    1996-12-31

    Fatigue crack growth has been measured in a laminated metal composite (LMC) consisting of alternating layers of AA6090/SiC/25p metal matrix composite (MMC) and AA5182 alloy. This material was tested in both as-pressed (F temper) and aged (T6 temper) conditions. Corresponding crack growth measurements were made in self-laminates of both the MMC and AA5182 materials to examine the role of the interfaces.

  9. Fracture and crack growth in orthotropic laminates

    NASA Technical Reports Server (NTRS)

    Goree, James G.; Kaw, Autar K.

    1985-01-01

    A mathematical model based on the classical shear-lag assumptions is used to study the residual strength and fracture behavior of composite laminates with symmetrically placed buffer strips. The laminate is loaded by a uniform remote longitudinal tensile strain and has initial damage in the form of a transverse crack in the parent laminate between buffer strips. The crack growth behavior as a function of material properties, number of buffer-strip plies, spacing, width of buffer strips, longitudinal matrix splitting, and debonding at the interface is studied. Buffer-strip laminates are shown to arrest fracture and increase the residual strengths significantly over those of one material laminates, with S-glass being a more effective buffer strip material than Kevlar in increasing the damage tolerance of graphite/epoxy panels. For a typical graphite/epoxy laminate with S-glass buffer-strips, the residual strength is about 2.4 times the residual strength of an all graphite/epoxy panel with the same crack length. Approximately 50% of this increase is due to the S-glass/epoxy buffer-strips, 40% due to longitudinal splitting of the buffer strip interface and 10% due to bonding.

  10. SEASONAL ABUNDANCE PATTERNS OF DIATOMS ON 'CLADOPHORA' IN LAKE HURON

    EPA Science Inventory

    Rocks bearing Cladophora were collected from May to November 1979 at two locations near Harbor Beach, Michigan, in Lake Huron to document seasonal patterns of epiphytic diatom abundance and diatom proportion of the Cladophora-epiphyte assemblage biomass in an area receiving efflu...

  11. In search of new tractable diatoms for experimental biology.

    PubMed

    Chepurnov, Victor A; Mann, David G; von Dassow, Peter; Vanormelingen, Pieter; Gillard, Jeroen; Inzé, Dirk; Sabbe, Koen; Vyverman, Wim

    2008-07-01

    Diatoms are a species-rich group of photosynthetic eukaryotes, with enormous ecological significance and great potential for biotechnology. During the last decade, diatoms have begun to be studied intensively using modern molecular techniques and the genomes of four diatoms have been wholly or partially sequenced. Although new insights into the biology and evolution of diatoms are accumulating rapidly due to the availability of reverse genetic tools, the full potential of these molecular biological approaches can only be fully realized if experimental control of sexual crosses becomes firmly established and widely accessible to experimental biologists. Here we discuss the issue of choosing new models for diatom research, by taking into account the broader context of diatom mating systems and the place of sex in relation to the intricate cycle of cell size reduction and restitution that is characteristic of most diatoms. We illustrate the results of our efforts to select and develop experimental systems in diatoms, using species with typical life cycle attributes, which could be used as future model organisms to complement existing ones. PMID:18536039

  12. 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

  13. A Phase Separation Model for the Nanopatterning of Diatom Biosilica

    Microsoft Academic Search

    Manfred Sumper

    2002-01-01

    Diatoms are encased in an intricately patterned wall that consists of amorphous silica. Species-specific fabrication of this ornate biomineral enables taxonomists to identify thousands of diatom species. The molecular mechanisms that control this nanofabrication and generate the diversity of patterns is not well understood. A simple model is described, in which repeated phase separation events during wall biogenesis are assumed

  14. Structural characteristics of a diatom community epiphytic on Ruppia maritima

    Microsoft Academic Search

    Michael J. Sullivan

    1977-01-01

    Epiphytic diatoms were collected from both the leaves and internodes of Ruppia maritima in a New Jersey salt marsh during the growing season of the host plant. Community diversity (H' and the number of diatom taxa) values were initially high as Ruppia began its growth, but quickly dropped to sustained low levels as vegetative growth of the host ceased and

  15. Effect of laminate edge conditions on the formation of microvoids in composite laminates

    NASA Astrophysics Data System (ADS)

    Anderson, J. P.; Altan, M. C.

    2015-05-01

    Manufacturing defects such as microvoids are common in thermoset composite components and are known to negatively affect their strength. The resin pressure developed in and the resin flow out from the laminates during cure have been reported to be the primary factors influencing the final void content of a composite component. In this work, the effect of laminate edge conditions during the cure process on the formation of microvoids was experimentally investigated. This was achieved by fabricating eight-ply laminates from TenCate® BT250/7781 prepreg in a hot-press at a constant cure pressure of 170 kPa while limiting the laminate perimeter available for resin flow by 0%, 25%, 50%, 75%, and 100%. The individual plies of these five laminates were conditioned at 99% relative humidity before curing to maximize the moisture present in the lay-up before fabrication. The presence of moisture in the lay-ups was expected to promote void formation and allow the effect of restricting flow at the edges of a laminate to be better identified. The restriction of resin outflow was found to cause the average characteristic void diameter to decrease by 17% and void content to rise by 33%. This phenomenon was identified to be a result of the outflow restriction increasing the number of voids trapped within the laminate and indicates that for laminates cured at low pressures resin outflow is the dominant mechanism for void reduction.

  16. Optimal Strength Design for Fiber-Metal Laminates and Fiber-reinforced Plastic Laminates

    Microsoft Academic Search

    Wenjie Peng; Jianqiao Chen; Junhong Wei; Wenqiong Tu

    2011-01-01

    Optimal strength design of fiber-reinforced plastic (FRP) laminates and fiber-metal laminates (FML) is studied in this article. An optimization approach that integrates the particle swarm optimization algorithm and a general finite element code ANSYS was developed. ANSYS is utilized to obtain the failure index as fitness function and the optimum fitness is obtained by altering the fiber orientations. The strength

  17. Diatomic sulfur (S/sub 2/)

    SciTech Connect

    Steliou, K.; Salama, P.; Brodeur, D.; Gareau, Y.

    1987-02-04

    Recently, they described a group 14 metal assisted procedure for the preparation and Diels-Alder trapping of S/sub 2/, a highly reactive diatomic form of elemental sulfur. Their continuing efforts in this area have led us to develop an alternate synthetic method that affords this reactive dienophile by, to their knowledge, an unprecedented intramolecular carbon-carbon bond-forming reaction. The ability to generate S/sub 2/ conveniently, and at temperatures more conductive to Diels-Alder trapping, makes it synthetically attractive to use. The present procedure should therefore, find widespread application in the synthesis of 1,2-dithiins.

  18. Diatoms-from cell wall biogenesis to nanotechnology.

    PubMed

    Kröger, Nils; Poulsen, Nicole

    2008-01-01

    Diatoms are single-celled algae that produce intricately structured cell walls made of nanopatterned silica (SiO(2)). The cell wall structure is a species-specific characteristic demonstrating that diatom silica morphogenesis is genetically encoded. Understanding the molecular mechanisms by which a single cell executes the morphogenetic program for the formation of an inorganic material (biomineralization) is not only a fascinating biological problem, but also of great interest for nanomaterials science and technology. Recently, analysis of the organic components associated with diatom silica, the development of techniques for molecular genetic manipulation of diatoms, and two diatom genome sequencing projects are providing insight into the composition and mechanism of the remarkable biosilica-forming machinery. PMID:18983255

  19. 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

  20. Modelling diatom growth in turbulent waters.

    PubMed

    Patel, Dipen; Guganesharajah, K; Thake, Brenda

    2004-06-01

    Algal models used as tools in the management of algal blooms may be inaccurate because representation of mixing processes is often oversimplified. A testable 3-D algal model for prediction of algal growth in turbulent surface waters was developed based on the Eulerian water quality model, HYDRO-3D. Out-door mesocosm experiments on the growth of the diatom Skeletonema costatum showed no evidence that diatom growth is significantly affected by light/dark fluctuations brought about by turbulent mixing, and no direct effects of turbulence on phytoplankton physiology were required in the algal model. The algal model was successfully calibrated and validated against mesocosm data and field data from Poplar Dock, London Docklands. Application of the model gave credible results for the hypothetical growth of S. costatum in Poplar Dock under a wide range of wind speeds and surface irradiances. However, differences between the results of a full 3-D simulation and a simplified 1-D representation of Poplar Dock were minimal, and no clear conclusions could be drawn on the superiority of 3-D models over 1-D models for simulation of complex flows in natural water bodies. PMID:15207602

  1. Diatom Milking: A Review and New Approaches

    PubMed Central

    Vinayak, Vandana; Manoylov, Kalina M.; Gateau, Hélène; Blanckaert, Vincent; Hérault, Josiane; Pencréac’h, Gaëlle; Marchand, Justine; Gordon, Richard; Schoefs, Benoît

    2015-01-01

    The rise of human populations and the growth of cities contribute to the depletion of natural resources, increase their cost, and create potential climatic changes. To overcome difficulties in supplying populations and reducing the resource cost, a search for alternative pharmaceutical, nanotechnology, and energy sources has begun. Among the alternative sources, microalgae are the most promising because they use carbon dioxide (CO2) to produce biomass and/or valuable compounds. Once produced, the biomass is ordinarily harvested and processed (downstream program). Drying, grinding, and extraction steps are destructive to the microalgal biomass that then needs to be renewed. The extraction and purification processes generate organic wastes and require substantial energy inputs. Altogether, it is urgent to develop alternative downstream processes. Among the possibilities, milking invokes the concept that the extraction should not kill the algal cells. Therefore, it does not require growing the algae anew. In this review, we discuss research on milking of diatoms. The main themes are (a) development of alternative methods to extract and harvest high added value compounds; (b) design of photobioreactors; (c) biodiversity and (d) stress physiology, illustrated with original results dealing with oleaginous diatoms. PMID:25939034

  2. 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

  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. Molecular characterization of Xenopus lamin LIV reveals differences in the lamin composition of sperms in amphibians and mammals

    PubMed Central

    von Moeller, Friederike; Barendziak, Tanja; Apte, Ketaki; Goldberg, Martin W

    2010-01-01

    Lamins are nuclear intermediate filament proteins. They are involved in most nuclear activities and are essential for retaining the mechano-elastic properties of the nucleus. Somatic cells of vertebrates express lamins A, B1 and B2 while lamin LIII, a major component of the amphibian oocyte lamina is absent in mammals. The organization of the lamina of germ cells differs significantly from that of somatic cells. Mammalian spermatogenic cells express two short lamins, C2 and B3, that are splice isoforms of lamin A and B2, respectively. Here we identify the previously described Xenopus lamin LIV as splice variant of the lamin LIII gene. LIV contains 40 extra residues in coil 2A of the rod domain, which results in altered assembly properties. Xenopus lamin LIV and mammalian B3 assemble into short structures rather than into long IF-like filaments. Expression of lamin LIV is restricted to male germ cells suggesting that it might be the functional equivalent of mammalian lamin B3. We provide evidence that lamins C2 and B3 are restricted to the mammalian lineage and describe the lamin composition of Xenopus sperm. Our results show that the evolution of germ cell-specific lamins followed separate and distinctly different paths in amphibians and mammals. PMID:21327107

  5. Elastic Coupling Effects in Tapered Sandwich Panels with Laminated

    E-print Network

    Vel, Senthil

    Elastic Coupling Effects in Tapered Sandwich Panels with Laminated Anisotropic Composite Facings theory for the analysis of tapered sandwich panels with laminated anisotropic facings is presented. Unlike sandwich panels of uniform depth, the response of tapered sandwich panels is counterintuitive

  6. GENERAL THEORY OF COUPLED THERMALLY STABLE ANISOTROPIC LAMINATES

    E-print Network

    Paris-Sud XI, Université de

    applications. Coupled laminates can be used, for instance, for obtaining a passive control of the twist of rotor blades of helicopters or of wind-mills. Usually, structural composite laminates are obtained

  7. SIZE EFFECTS ON IMPACT RESPONSE OF COMPOSITE LAMINATES

    Microsoft Academic Search

    Dahsin Liu; Basavaraju B. Raju; Xinglai Dang

    1998-01-01

    Delamination was known to be one of the most important damage modes in composite laminates subjected to impact loading. In an effort to further understand the impact response of composite laminates, various degrees of impact ranging from subperforation to perforation were introduced to glass\\/epoxy laminates through an instrumented drop-weight impactor. In addition, composite laminates of various in-plane dimensions and thicknesses

  8. An inherent instability in fiber-reinforced composite laminates

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.

    1981-01-01

    Presented is a theory to predict the room-temperature shape of unsymmetric laminates. The theory is an extension of classical lamination theory and includes the effects of geometric nonlinearities. It is shown that the saddle shape predicted by the classical theory can actually be an unstable shape and a laminate will assume a cylindrical shape instead. The phenomena is coupled to the length, width, and thickness of the laminate.

  9. Copepod population-specific response to a toxic diatom diet.

    PubMed

    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

  10. Molecular Detection of a Potentially Toxic Diatom Species

    PubMed Central

    Dhar, Bidhan Chandra; Cimarelli, Lucia; Singh, Kumar Saurabh; Brandi, Letizia; Brandi, Anna; Puccinelli, Camilla; Marcheggiani, Stefania; Spurio, Roberto

    2015-01-01

    A few diatom species produce toxins that affect human and animal health. Among these, members of the Pseudo-nitzschia genus were the first diatoms unambiguously identified as producer of domoic acid, a neurotoxin affecting molluscan shell-fish, birds, marine mammals, and humans. Evidence exists indicating the involvement of another diatom genus, Amphora, as a potential producer of domoic acid. We present a strategy for the detection of the diatom species Amphora coffeaeformis based on the development of species-specific oligonucleotide probes and their application in microarray hybridization experiments. This approach is based on the use of two marker genes highly conserved in all diatoms, but endowed with sufficient genetic divergence to discriminate diatoms at the species level. A region of approximately 450 bp of these previously unexplored marker genes, coding for elongation factor 1-a (eEF1-a) and silicic acid transporter (SIT), was used to design oligonucleotide probes that were tested for specificity in combination with the corresponding fluorescently labeled DNA targets. The results presented in this work suggest a possible use of this DNA chip technology for the selective detection of A. coffeaeformis in environmental settings where the presence of this potential toxin producer may represent a threat to human and animal health. In addition, the same basic approach can be adapted to a wider range of diatoms for the simultaneous detection of microorganisms used as biomarkers of different water quality levels. PMID:25955528

  11. Self-assembled diatom substrates with plasmonic functionality

    NASA Astrophysics Data System (ADS)

    Kwon, Sun Yong; Park, Sehyun; Nichols, William T.

    2014-04-01

    Marine diatoms have an exquisitely complex exoskeleton that is promising for engineered surfaces such as sensors and catalysts. For such applications, creating uniform arrays of diatom frustules across centimeter scales will be necessary. Here, we present a simple, low-cost floating interface technique to self-assemble the diatom frustules. We show that well-prepared diatoms form floating hexagonal close-packed arrays at the air-water interface that can be transferred directly to a substrate. We functionalize the assembled diatom surfaces with gold and characterize the plasmonic functionality by using surface enhanced Raman scattering (SERS). Thin gold films conform to the complex, hierarchical diatom structure and produce a SERS enhancement factor of 2 × 104. Small gold nanoparticles attached to the diatom's surface produce a higher enhancement of 7 × 104 due to stronger localization of the surface plasmons. Taken together, the large-scale assembly and plasmonic functionalization represent a promising platform to control the energy and the material flows at a complex surface for applications such as sensors and plasmonic enhanced catalysts.

  12. 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; Koçer, 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

  13. [Applications of diatom in river health assessment: a review].

    PubMed

    Li, Guo-Chen; Liu, Lu-San; Wang, Xing; Li, Li

    2012-09-01

    Diatom, as a kind of autotrophic photosynthetic eukaryotic algae, is an important primary producer in aquatic ecosystem, and can reflect the average status of water environment. As the bio-indicators of the environment, Nitzschia communis, Navicula minuscula, and Gomphonema parvulum can indicate the eutrophication of waters, whereas Gomphonema angustum, Epithemia adnata, and Diatoma moniliformis can indicate the oligotrophication of waters. Cyclotella bodanica, Neidium affine, and Eunotia exigua are all the eosinophilic species that can indicate waters acidity, Aminutissimum nodusa can indicate water's Cu concentration, and Synedra ulna can indicate the Zn concentration in waters. Some other diatoms can also indicate water' s contamination. This paper reviewed the research progress on the applications of diatom and diatom indices in river health assessment, pointed out the related existing problems, and put forward some future research directions, e. g., further perfect the classification and identification of diatoms, broadly carry out the researches of diatom indices upon different areas and conditions, pay more attention to the screening of diatom bio-integrality indices, and establish a benchmark which suits for the assessment of water quality. PMID:23286024

  14. Preliminary evaluation of hybrid titanium composite laminates

    NASA Technical Reports Server (NTRS)

    Miller, J. L.; Progar, D. J.; Johnson, W. S.; St.clair, T. L.

    1994-01-01

    In this study, the mechanical response of hybrid titanium composite laminates (HTCL) was evaluated at room and elevated temperatures. Also, the use of an elastic-plastic laminate analysis program for predicting the tensile response from constituent properties was verified. The improvement in mechanical properties achieved by the laminates was assessed by comparing the results of static strength and constant amplitude fatigue tests to those for monolithic titanium sheet. Two HTCL were fabricated with different fiber volume fractions, resin layer thicknesses, and resins. One panel was thicker and was more poorly bonded in comparison to other. Consequently, the former had a lower tensile strength, while fewer cracks grew in this panel and at a slower rate. Both panels showed an improvement in fatigue life of almost two orders of magnitude. The model predictions were also in good agreement with the experimental results for both HTCL panels.

  15. On thermal edge effects in composite laminates

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1976-01-01

    Results are presented for a finite-element investigation of the combined influence of edge effects due to mechanical and thermal mismatch in composite laminates with free edges. Laminates of unidirectional boron/epoxy symmetrically bonded to sheets of aluminum and titanium were studied. It is shown that interlaminar thermal stresses may be more significant than the interlaminar stresses due to loading only. In addition, the stresses due to thermal mismatch may be of the same sign as those due to Poisson's mismatch or they may be of opposite sign depending upon material properties, stacking sequence, and direction of loading. The paper concludes with a brief discussion of thermal stresses in all-composite laminates.

  16. 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.

  17. 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.

  18. Damage initiation and propagation in metal laminates

    SciTech Connect

    Riddle, R.A.; Lesuer, D.R.; Syn, C.K.

    1996-07-26

    The metal laminates proposed here for aircraft structures are Al alloy interlayers between Al alloy based metal matrix composite (MMC) plates reinforced with Si carbide particles. Properties to be tailored for jet engine fan containment and wing and auxiliary support structures include the important property fracture toughness. A method was developed for simulating and predicting crack initiation/growth using finite element analysis and fracture mechanics. An important key in predicting the failure is the tie- break slideline with prescribed (chosen based on J Integral calculations) effective plastic strain to failure in elements along the slideline. More development of the method is needed, particularly in its correlation with experimental data from various fracture toughness and strength tests of metal laminates. Results show that delamination at the interface of the ductile interlayer and MMC material can add significantly to the energy required to propagate a crack through a metal laminate. 11 figs, 7 refs.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. Stress Analysis of Thick Laminated Composite and Sandwich Plates

    Microsoft Academic Search

    James M. Whitney

    1972-01-01

    Because of the relatively soft interlaminar shear modulus in high per formance composites, laminated plate theory based on the Kirchhoff hypothesis becomes inaccurate for determining gross plate response and internal stresses of thick composites and sandwich type laminates. In this paper a procedure is developed for accurately calculating the mechanical behavior of a thick laminated composite or sandwich plate of

  4. 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.

  5. Multi-layer laminate structure and manufacturing method

    DOEpatents

    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.

  6. 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.

  7. NONLINEAR ACOUSTIC IMAGING OF STRUCTURAL DAMAGES IN LAMINATED COMPOSITES

    E-print Network

    Boyer, Edmond

    are performed on a carbon fiber/epoxy laminated composite plate with barely visible impact damageNONLINEAR ACOUSTIC IMAGING OF STRUCTURAL DAMAGES IN LAMINATED COMPOSITES L. Pieczonka1 , A. Klepka1 for imaging of structural damage in a laminated composite plate. The techniques that have been considered

  8. Stresses in laminated glass subject to low velocity impact

    Microsoft Academic Search

    F. W. Flocker; L. R. Dharani

    1997-01-01

    Finite element analysis is used to study small, low velocity missile impact of laminated architectural glass. The impact situation models that commonly observed during severe windstorms in which small, hard missiles impact laminated glass windows in large buildings. Architectural laminated glass is typically made of two soda-lime glass plies separated by a clear, sticky, polyvinyl butyral (PVB) interlayer. In order

  9. Residual Stresses in Carbon Fibre-Thermoplastic Matrix Laminates

    Microsoft Academic Search

    G. Jeronimidis; A. T. Parkyn

    1988-01-01

    Residual stresses in composite laminates depend on thermoelastic properties of the material and processing temperatures. Their distribution in the various laminae is a func tion of stacking sequence and ply orientation. In this work residual stresses in APC-2 cross-ply laminates have been investigated. Predictions based on classical laminate theory are compared to measured levels of residual stress obtained from a

  10. 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 polymer cathode that can be laminated on top of an organic photovoltaic cell was previously reported,14

  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. Spectroscopically Accurate Calculations of the Rovibrational Energies of Diatomic Hydrogen

    NASA Astrophysics Data System (ADS)

    Perry, Jason

    2005-05-01

    The Born-Oppenheimer approximation has been used to calculate the rotational and vibrational states of diatomic hydrogen. Because it is an approximation, our group now wants to use a Born-Oppenheimer potential to calculate the electronic energy that has been corrected to match closely with spectroscopic results. We are using a code that has corrections for adiabatic, relativistic, radiative, and non-adiabatic effects. The rovibrational energies have now been calculated for both bound and quasi-bound states. We also want to compute quadrupole transition probabilities for diatomic hydrogen. These calculations aspire to investigate diatomic hydrogen in astrophysical environments.

  13. Reliability analysis of continuous fiber composite laminates

    NASA Technical Reports Server (NTRS)

    Thomas, David J.; Wetherhold, Robert C.

    1991-01-01

    This paper describes two methods, the maximum distortion energy (MDE) and the principle of independent action (PIA), developed for the analysis of the reliability of a single continuous composite lamina. It is shown that, for the typical laminated plate structure, the individual lamina reliabilities can be combined in order to produce the upper and the lower bounds of reliability for the laminate, similar in nature to the bounds on properties produced from variational elastic methods. These limits were derived for both the interactive and the model failure considerations. Analytical expressions were also derived for the sensitivity of the reliability limits with respect to changes in the Weibull parameters and in loading conditions.

  14. Magneto-optical trapping of diatomic molecules

    E-print Network

    Hummon, Matthew T; Stuhl, Benjamin K; Collopy, Alejandra L; Xia, Yong; Ye, Jun

    2012-01-01

    The development of the magneto-optical trap revolutionized the fields of atomic and quantum physics by providing a simple method for the rapid production of ultracold, trapped atoms. A similar technique for producing a diverse set of dense, ultracold diatomic molecular species will likewise transform the study of strongly interacting quantum systems, precision measurement, and physical chemistry. We demonstrate one- and two-dimensional transverse laser cooling and magneto-optical trapping of the polar molecule yttrium (II) oxide (YO). Using a quasicycling optical transition we observe transverse Doppler cooling of a YO molecular beam to a temperature of 5 mK, limited by interaction time. With the addition of an oscillating magnetic quadrupole field we demonstrate a transverse magneto-optical trap and achieve temperatures of 2 mK.

  15. Edge effects in angle-ply composite laminates

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    This paper presents the results of a zeroth-order solution for edge effects in angle-ply composite laminates obtained using perturbation techniques and a limiting free body approach. The general solution for edge effects in laminates of arbitrary angle ply is applied to the special case of a (+ or - 45)s graphite/epoxy laminate. Interlaminar stress distributions are obtained as a function of the laminate thickness-to-width ratio and compared to finite difference results. The solution predicts stable, continuous stress distributions, determines finite maximum tensile interlaminar normal stress and provides mathematical evidence for singular interlaminar shear stresses in (+ or - 45) graphite/epoxy laminates.

  16. Composite laminates with negative through-the-thickness Poisson's ratios

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1984-01-01

    A simple analysis using two dimensional lamination theory combined with the appropriate three dimensional anisotropic constitutive equation is presented to show some rather surprising results for the range of values of the through-the-thickness effective Poisson's ratio nu sub xz for angle ply laminates. Results for graphite-epoxy show that the through-the-thickness effective Poisson's ratio can range from a high of 0.49 for a 90 laminate to a low of -0.21 for a + or - 25s laminate. It is shown that negative values of nu sub xz are also possible for other laminates.

  17. Nonlinear laminate analysis for metal matrix fiber composites

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A nonlinear laminate analysis is described for predicting the mechanical behavior (stress-strain relationships) of angle-ply laminates in which the matrix is strained nonlinearly by both the residual stress and the mechanical load and in which additional nonlinearities are induced due to progressive fiber fractures and ply relative rotations. The nonlinear laminate analysis is based on linear composite mechanics and a piece-wise linear laminate analysis to handle the nonlinear responses. Results obtained by using this nonlinear analysis on boron-fiber/aluminum-matrix angle-ply laminates agree well with experimental data. The results shown illustrate the in situ ply stress-strain behavior and synergistic strength enhancement.

  18. Nonlinear laminate analysis for metal matrix fiber composites

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A nonlinear laminate analysis is described for predicting the mechanical behavior (stress-strain relationships) of angleplied laminates in which the matrix is strained nonlinearly by both the residual stress and the mechanical load and in which additional nonlinearities are induced due to progressive fiber fractures and ply relative rotations. The nonlinear laminate analysis (NLA) is based on linear composite mechanics and a piece wise linear laminate analysis to handle the nonlinear responses. Results obtained by using this nonlinear analysis on boron fiber/aluminum matrix angleplied laminates agree well with experimental data. The results shown illustrate the in situ ply stress-strain behavior and synergistic strength enhancement.

  19. Composition of Exopolymer Particles Produced By Marine Diatoms

    E-print Network

    Hinson, Audra

    2013-02-04

    biotic organism could heavily impact species differentiation in the ocean. Exopolymer particles are excreted by phytoplankton, including diatoms. These particles are understood to contain carbohydrates and protein that can potentially serve as a food...

  20. Theory of laminated turbulence: open questions

    E-print Network

    E. Kartashova

    2006-11-17

    Theory of laminated turbulnece includes continuous layer of turbulence (statistical description, kinetic equations, Zakharov-Kolmogorov spectra, etc) AND discrete layer of turbulence (isolated groups of interacting waves, no statisticaldescription). This theory is presented, examples of possible applications are given, important open questions are formulated.

  1. Impact resistance of composite laminated sandwich plates

    Microsoft Academic Search

    Chun-Gon Kim; Eui-Jin Jun

    1992-01-01

    Investigated are the effects of face layup sequence and core density of a sandwich plate on the impact delamination area of the laminated facesheet. The sandwich plate is made of graphite\\/epoxy faces and Nomex honeycomb core. The size and shape of delamination due to impact at each interply location have been measured by the room temperature deply technique. The shape

  2. 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.

  3. Tevatron I: Large Bore Quad lamination analysis

    SciTech Connect

    Leininger, M.

    1982-10-26

    Stacking, compression, and welding of the laminations for the TeV I Large Bore Quad results in a deformation due to springback which is unacceptable due to magnetic field requirements. ANSYS has been used to analyze a solution to this problem.

  4. Reliability analysis of continuous fiber composite laminates

    NASA Technical Reports Server (NTRS)

    Thomas, David J.; Wetherhold, Robert C.

    1990-01-01

    A composite lamina may be viewed as a homogeneous solid whose directional strengths are random variables. Calculation of the lamina reliability under a multi-axial stress state can be approached by either assuming that the strengths act separately (modal or independent action), or that they interact through a quadratic interaction criterion. The independent action reliability may be calculated in closed form, while interactive criteria require simulations; there is currently insufficient data to make a final determination of preference between them. Using independent action for illustration purposes, the lamina reliability may be plotted in either stress space or in a non-dimensional representation. For the typical laminated plate structure, the individual lamina reliabilities may be combined in order to produce formal upper and lower bounds of reliability for the laminate, similar in nature to the bounds on properties produced from variational elastic methods. These bounds are illustrated for a (0/plus or minus 15)sub s Graphite/Epoxy (GR/EP) laminate. And addition, simple physically plausible phenomenological rules are proposed for redistribution of load after a lamina has failed. These rules are illustrated by application to (0/plus or minus 15)sub s and (90/plus or minus 45/0)sub s GR/EP laminates and results are compared with respect to the proposed bounds.

  5. Plastic working of laminated composite materials

    Microsoft Academic Search

    S. V. Voronov; D. G. Devoino

    1982-01-01

    Plastic working can be successfully employed for increasing the strength of the joint in a laminated composite material whose components react with each other during high-speed cladding, with the formation of brittle intermetallic compouds. At the same time, by suitable choice of reduction and mismatch, it is possible to produce straight bimetallic strips by rolling them with mismatched peripheral roll

  6. The Bearing Strength of Fiber Metal Laminates

    Microsoft Academic Search

    R. G. J. Van Rooijen; J. Sinke; T. J. De Vries; S. Van Der Zwaag

    2006-01-01

    The bearing strength, in particular the edge distance sensitivity, of several fiber metal laminates of the GLARE family is experimentally evaluated. The behavior of the fiber layer is investigated in detail to obtain a better understanding of its failure mode. Parallel with these experiments, the bearing behavior is studied using a finite element (FE) model. The plasticity in the metal

  7. Space-time Multiscale Laminated Theory

    Microsoft Academic Search

    Ryan Lund; Jacob Fish

    2004-01-01

    Multiscale computational techniques in space and time are developed to study the impact response of thin, elastic, laminated composites. The displacement field is approximated using asymptotic expansion in space and time. Using the homoge- nization procedure in space and time, nonlocal membrane and bending equations of motion are derived. The nonlocal equations are stabilized to filter out the higher frequency

  8. A new damage model for composite laminates

    Microsoft Academic Search

    Marcelo Leite Ribeiro; Volnei Tita; Dirk Vandepitte

    Aircraft composite structures must have high stiffness and strength with low weight, which can guarantee the increase of the pay-load for airplanes without losing airworthiness. However, the mechanical behavior of composite laminates is very complex due the inherent anisotropy and heterogeneity. Many researchers have developed different failure progressive analyses and damage models in order to predict the complex failure mechanisms.

  9. 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.

  10. Seasonal Diatom Variability and Paleolimnological Inferences – A Case Study

    Microsoft Academic Search

    Dörte Köster; Reinhard Pienitz

    2006-01-01

    The seasonality of physical, chemical, and biological water variables is a major characteristic of temperate, dimictic lakes.\\u000a Yet, few investigations have considered the potential information that is encoded in seasonal dynamics with respect to the\\u000a paleolimnological record. We used a one-year sequence of diatoms obtained from sediment traps and water samples, as well as\\u000a the sedimentary diatom record covering the

  11. Diversity and Evolutionary History of Iron Metabolism Genes in Diatoms

    PubMed Central

    Groussman, Ryan D.; Parker, Micaela S.; Armbrust, E. Virginia

    2015-01-01

    Ferroproteins arose early in Earth’s history, prior to the emergence of oxygenic photosynthesis and the subsequent reduction of bioavailable iron. Today, iron availability limits primary productivity in about 30% of the world’s oceans. Diatoms, responsible for nearly half of oceanic primary production, have evolved molecular strategies for coping with variable iron concentrations. Our understanding of the evolutionary breadth of these strategies has been restricted by the limited number of species for which molecular sequence data is available. To uncover the diversity of strategies marine diatoms employ to meet cellular iron demands, we analyzed 367 newly released marine microbial eukaryotic transcriptomes, which include 47 diatom species. We focused on genes encoding proteins previously identified as having a role in iron management: iron uptake (high-affinity ferric reductase, multi-copper oxidase, and Fe(III) permease); iron storage (ferritin); iron-induced protein substitutions (flavodoxin/ferredoxin, and plastocyanin/cytochrome c6) and defense against reactive oxygen species (superoxide dismutases). Homologs encoding the high-affinity iron uptake system components were detected across the four diatom Classes suggesting an ancient origin for this pathway. Ferritin transcripts were also detected in all Classes, revealing a more widespread utilization of ferritin throughout diatoms than previously recognized. Flavodoxin and plastocyanin transcripts indicate possible alternative redox metal strategies. Predicted localization signals for ferredoxin identify multiple examples of gene transfer from the plastid to the nuclear genome. Transcripts encoding four superoxide dismutase metalloforms were detected, including a putative nickel-coordinating isozyme. Taken together, our results suggest that the majority of iron metabolism genes in diatoms appear to be vertically inherited with functional diversity achieved via possible neofunctionalization of paralogs. This refined view of iron use strategies in diatoms elucidates the history of these adaptations, and provides potential molecular markers for determining the iron nutritional status of different diatom species in environmental samples. PMID:26052941

  12. Opening the gateways for diatoms primes Earth for Antarctic glaciation

    NASA Astrophysics Data System (ADS)

    Egan, Katherine E.; Rickaby, Rosalind E. M.; Hendry, Katharine R.; Halliday, Alex N.

    2013-08-01

    The abrupt onset of Antarctic glaciation during the Eocene-Oligocene Transition (?33.7 Ma, Oi1) is linked to declining atmospheric pCO2 levels, yet the mechanisms that forced pCO2 decline remain elusive. Biogenic silicon cycling is inextricably linked to both long and short term carbon cycling through the diatoms, siliceous walled autotrophs which today account for up to 40% of primary production. It is hypothesised that during the Late Eocene a sharp rise in diatom abundance could have contributed to pCO2 drawdown and global cooling by increasing the proportion of organic carbon buried in marine sediment. Diatom and sponge silicon isotope ratios (?30Si) are here combined for the first time to reconstruct the late Eocene-early Oligocene ocean silicon cycle and provide new insight into the role of diatom productivity in Antarctic glaciation. At ODP site 1090 in the Southern Ocean, a 0.6‰ rise in diatom ?30Si through the late Eocene documents increasing diatom silicic acid utilisation with high, near modern values attained by the earliest Oligocene. A concomitant 1.5‰ decline in sponge ?30Si at ODP site 689 on the Maud Rise tracks an approximate doubling of intermediate depth silicic acid concentration in the high southern latitudes. Intermediate depth silicic acid concentration peaked at ?31.5 Ma, coincident with the final establishment of a deepwater pathway through the Tasman Gateway and Drake Passage. These results suggest that upwelling intensification related to the spin-up of a circum-Antarctic current may have driven late Eocene diatom proliferation. Organic carbon burial associated with higher diatom abundance and export provides a mechanism that can account for pCO2 drawdown not only at, but also prior to, Antarctic glaciation as required by a pCO2 'threshold' mechanism for ice sheet growth.

  13. Diatoms—From Cell Wall Biogenesis to Nanotechnology

    Microsoft Academic Search

    Nils Kröger; Nicole Poulsen

    2008-01-01

    Diatoms are single-celled algae that produce intricately structured cell walls made of nanopatterned silica (SiO2). The cell wall structure is a species-specific characteristic demonstrating that diatom silica mor- phogenesis is genetically encoded. Understanding the molecular mech- anisms by which a single cell executes the morphogenetic program for the formation of an inorganic material (biomineralization) is not only a fascinating biological

  14. Tensile stress-strain behavior of boron/aluminum laminates

    NASA Technical Reports Server (NTRS)

    Sova, J. A.; Poe, C. C., Jr.

    1978-01-01

    The tensile stress-strain behavior of five types of boron/aluminum laminates was investigated. Longitudinal and transverse stress-strain curves were obtained for monotonic loading to failure and for three cycles of loading to successively higher load levels. The laminate strengths predicted by assuming that the zero deg plies failed first correlated well with the experimental results. The stress-strain curves for all the boron/aluminum laminates were nonlinear except at very small strains. Within the small linear regions, elastic constants calculated from laminate theory corresponded to those obtained experimentally to within 10 to 20 percent. A limited amount of cyclic loading did not affect the ultimate strength and strain for the boron/aluminum laminates. The laminates, however, exhibited a permanent strain on unloading. The Ramberg-Osgood equation was fitted to the stress-strain curves to obtain average curves for the various laminates.

  15. Ultrasonic monitoring of asymmetric carbon fibre reinforced aluminum laminates

    NASA Astrophysics Data System (ADS)

    Zhao, Junqing; Yang, Fan; Wang, Rongguo

    2013-08-01

    Asymmetric carbon fibre reinforced aluminum alloy laminates was manufactured for the purpose with repeat tensile test, which will be applied in composite pressure vessel. Ultrasonic C scan and A scan approach are used to evaluate the damage of the asymmetric CFRP-Al (carbon fibre reinforced aluminum alloy) laminates. Nondestructive detection is carried out for the CFRP-Al laminates before and after tensile test. Comparison results and pulse echo analysis show that when subjected to repeat tensile test with 70% elastic limit strain load of the CFRP laminates, the interface debonding between CFRP and Al will not occur but the delamination within CFRP laminates becomes the main damage of the asymmetric CFRP-Al laminates. This investigation indicated that combined ultrasonic C scan and A scan is available for damage evaluation of fibre metal laminates.

  16. Compression failure of angle-ply laminates

    NASA Technical Reports Server (NTRS)

    Peel, Larry D.; Hyer, Michael W.; Shuart, Mark J.

    1991-01-01

    The present work deals with modes and mechanisms of failure in compression of angle-ply laminates. Experimental results were obtained from 42 angle-ply IM7/8551-7a specimens with a lay-up of ((plus or minus theta)/(plus or minus theta)) sub 6s where theta, the off-axis angle, ranged from 0 degrees to 90 degrees. The results showed four failure modes, these modes being a function of off-axis angle. Failure modes include fiber compression, inplane transverse tension, inplane shear, and inplane transverse compression. Excessive interlaminar shear strain was also considered as an important mode of failure. At low off-axis angles, experimentally observed values were considerably lower than published strengths. It was determined that laminate imperfections in the form of layer waviness could be a major factor in reducing compression strength. Previously developed linear buckling and geometrically nonlinear theories were used, with modifications and enhancements, to examine the influence of layer waviness on compression response. The wavy layer is described by a wave amplitude and a wave length. Linear elastic stress-strain response is assumed. The geometrically nonlinear theory, in conjunction with the maximum stress failure criterion, was used to predict compression failure and failure modes for the angle-ply laminates. A range of wave length and amplitudes were used. It was found that for 0 less than or equal to theta less than or equal to 15 degrees failure was most likely due to fiber compression. For 15 degrees less than theta less than or equal to 35 degrees, failure was most likely due to inplane transverse tension. For 35 degrees less than theta less than or equal to 70 degrees, failure was most likely due to inplane shear. For theta less than 70 degrees, failure was most likely due to inplane transverse compression. The fiber compression and transverse tension failure modes depended more heavily on wave length than on wave amplitude. Thus using a single parameter, such as a ratio of wave amplitude to wave length, to describe waviness in a laminate would be inaccurate. Throughout, results for AS4/3502, studied previously, are included for comparison. At low off-axis angles, the AS4/3502 material system was found to be less sensitive to layer waviness than IM7/8551-7a. Analytical predictions were also obtained for laminates with waviness in only some of the layers. For this type of waviness, laminate compression strength could also be considered a function of which layers in the laminate were wavy, and where those wavy layers were. Overall, the geometrically nonlinear model correlates well with experimental results.

  17. 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.

  18. 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.

  19. Marine Polysaccharide Networks and Diatoms at the Nanometric Scale

    PubMed Central

    Svetli?i?, Vesna; Žuti?, Vera; Pletikapi?, Galja; Radi?, Tea Miši?

    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

  20. Responses of diatom communities to hydrological processes during rainfall events

    NASA Astrophysics Data System (ADS)

    Wu, Naicheng; Faber, Claas; Ulrich, Uta; Fohrer, Nicola

    2015-04-01

    The importance of diatoms as a tracer of hydrological processes has been recently recognized (Pfister et al. 2009, Pfister et al. 2011, Tauro et al. 2013). However, diatom variations in a short-term scale (e.g., sub-daily) during rainfall events have not been well documented yet. In this study, rainfall event-based diatom samples were taken at the outlet of the Kielstau catchment (50 km2), a lowland catchment in northern Germany. A total of nine rainfall events were caught from May 2013 to April 2014. Non-metric multidimensional scaling (NMDS) revealed that diatom communities of different events were well separated along NMDS axis I and II, indicating a remarkable temporal variation. By correlating water level (a proxy of discharge) and different diatom indices, close relationships were found. For example, species richness, biovolume (?m3), Shannon diversity and moisture index01 (%, classified according to van Dam et al. 1994) were positively related with water level at the beginning phase of the rainfall (i.e. increasing limb of discharge peak). However, in contrast, during the recession limb of the discharge peak, diatom indices showed distinct responses to water level declines in different rainfall events. These preliminary results indicate that diatom indices are highly related to hydrological processes. The next steps will include finding out the possible mechanisms of the above phenomena, and exploring the contributions of abiotic variables (e.g., hydrologic indices, nutrients) to diatom community patterns. Based on this and ongoing studies (Wu et al. unpublished data), we will incorporate diatom data into End Member Mixing Analysis (EMMA) and select the tracer set that is best suited for separation of different runoff components in our study catchment. Keywords: Diatoms, Rainfall event, Non-metric multidimensional scaling, Hydrological process, Indices References: Pfister L, McDonnell JJ, Wrede S, Hlúbiková D, Matgen P, Fenicia F, Ector L, Hoffmann L. 2009. The rivers are alive: on the potential for diatoms as a tracer of water source and hydrological connectivity. Hydrological Processes 23: 2841-2845. Pfister L, Wetzel CE, Martínez-Carreras N, Frentress J, Ector L, Hoffmann L, McDonnell JJ. 2011. Do diatoms run downhill? Using biodiversity of terrestrial and aquatic diatoms to identify hydrological connectivity between aquatic zones in Luxembourg. AGU Fall Meeting. Tauro F, Martínez-Carreras N, Wetzel CE, Hissler C, Barnich F, Frentress J, Ector L, Hoffmann L, McDonnell JJ, Pfister L. 2013. Fluorescent diatoms as hydrological tracers: a proof of concept percolation experiment. EGU abstract, EGU2013-7687-4. van Dam H, Mertens A, Sinkeldam J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Netherlands Journal of Aquatic Ecology 28:117-133.

  1. An Elastic Model of Blebbing in Nuclear Lamin Meshworks

    NASA Astrophysics Data System (ADS)

    Funkhouser, Chloe; Sknepnek, Rastko; Shimi, Takeshi; Goldman, Anne; Goldman, Robert; Olvera de La Cruz, Monica

    2013-03-01

    A two-component continuum elastic model is introduced to analyze a nuclear lamin meshwork, a structural element of the lamina of the nuclear envelope. The main component of the lamina is a meshwork of lamin protein filaments providing mechanical support to the nucleus and also playing a role in gene expression. Abnormalities in nuclear shape are associated with a variety of pathologies, including some forms of cancer and Hutchinson-Gilford progeria syndrome, and are often characterized by protruding structures termed nuclear blebs. Nuclear blebs are rich in A-type lamins and may be related to pathological gene expression. We apply the two-dimensional elastic shell model to determine which characteristics of the meshwork could be responsible for blebbing, including heterogeneities in the meshwork thickness and mesh size. We find that if one component of the lamin meshwork, rich in A-type lamins, has a tendency to form a larger mesh size than that rich in B-type lamins, this is sufficient to cause segregation of the lamin components and also to form blebs rich in A-type lamins. The model produces structures with comparable morphologies and mesh size distributions as the lamin meshworks of real, pathological nuclei. A two-component continuum elastic model is introduced to analyze a nuclear lamin meshwork, a structural element of the lamina of the nuclear envelope. The main component of the lamina is a meshwork of lamin protein filaments providing mechanical support to the nucleus and also playing a role in gene expression. Abnormalities in nuclear shape are associated with a variety of pathologies, including some forms of cancer and Hutchinson-Gilford progeria syndrome, and are often characterized by protruding structures termed nuclear blebs. Nuclear blebs are rich in A-type lamins and may be related to pathological gene expression. We apply the two-dimensional elastic shell model to determine which characteristics of the meshwork could be responsible for blebbing, including heterogeneities in the meshwork thickness and mesh size. We find that if one component of the lamin meshwork, rich in A-type lamins, has a tendency to form a larger mesh size than that rich in B-type lamins, this is sufficient to cause segregation of the lamin components and also to form blebs rich in A-type lamins. The model produces structures with comparable morphologies and mesh size distributions as the lamin meshworks of real, pathological nuclei. Funded by US DoE Award DEFG02-08ER46539 and by the DDR&E and AFOSR under Award FA9550-10-1-0167; simulations performed on NU Quest cluster

  2. 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.

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

    PubMed

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Türke, 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

  4. What controls silicon isotope fractionation during dissolution of diatom opal?

    NASA Astrophysics Data System (ADS)

    Wetzel, F.; de Souza, G. F.; Reynolds, B. C.

    2014-04-01

    The silicon isotope composition of opal frustules from photosynthesising diatoms is a promising tool for studying past changes in the marine silicon cycle, and indirectly that of carbon. Dissolution of this opal may be accompanied by silicon isotope fractionation that could disturb the pristine silicon isotope composition of diatom opal acquired in the surface ocean. It has previously been shown that dissolution of fresh and sediment trap diatom opal in seawater does fractionate silicon isotopes. However, as the mechanism of silicon isotope fractionation remained elusive, it is uncertain whether opal dissolution in general is associated with silicon isotope fractionation considering that opal chemistry and surface properties are spatially and temporally (i.e. opal of different age) diverse. In this study we dissolved sediment core diatom opal in 5 mM NaOH and found that this process is not associated with significant silicon isotope fractionation. Since no variability of the isotope effect was observed over a wide range of dissolution rates, we can rule out the suggestion that back-reactions had a significant influence on the net isotope effect. Similarly, we did not observe an impact of temperature, specific surface area, or degree of undersaturation on silicon isotope partitioning during dissolution, such that these can most likely also be ruled out as controlling factors. We discuss the potential impacts of the chemical composition of the dissolution medium and age of diatom opal on silicon isotope fractionation during dissolution. It appears most likely that the controlling mechanism of silicon isotope fractionation during dissolution is related to the reactivity, or potentially, aluminium content of the opal. Such a dependency would imply that silicon isotope fractionation during dissolution of diatom opal is spatially and temporally variable. However, since the isotope effects during dissolution are small, the silicon isotope composition of diatom opal appears to be robust against dissolution in the deep sea sedimentary environment.

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

    PubMed Central

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Türke, 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

  6. Photodissociation imaging of diatomic sulfur (S2).

    PubMed

    Frederix, Pim W J M; Yang, Chung-Hsin; Groenenboom, Gerrit C; Parker, David H; Alnama, Koutayba; Western, Colin M; Orr-Ewing, Andrew J

    2009-12-31

    The photodissociation of diatomic sulfur, S(2), in the region of the first dissociation limit is studied with velocity map imaging. Correlated fine structure distributions P(J1,J2) for the two S((3)P(J)) fragments are determined at selected photolysis wavelengths. Image analysis of the speed distributions of the atomic fragments following product-state-specific detection results in a revision of the bond energy to D(0) = 35636.9 +/- 2.5 cm(-1) with respect to the lowest rovibrational level. This value arises from reinterpretation of previous spectroscopic data showing onset of predissociation in the B(3)Sigma(u)(-) state, as the measurements presented here demonstrate that the long-range correlation of the excited state invoked as causing the dissociation is S((3)P(2)) + S((3)P(2)) rather than S((3)P(2)) + S((3)P(1)). The wavelength dependence of data for the S((3)P(2)) + S((3)P(2)) channel suggests involvement of photoexcitation through the optically forbidden Herzberg continuum bands in addition to dissociation initiated via the optically allowed B(3)Sigma(u)(-)-X(3)Sigma(g)(-) and B''(3)Pi(u)-X(3)Sigma(g)(-) bands. Changes in product recoil velocity angular distributions and atomic angular momentum polarization were also measured as a function of dissociation wavelength. The results are compared with predictions from an adiabatic model for dissociation, which provides a basis for interpretation but does not explain quantitatively the experimental results. PMID:19754091

  7. Photodissociation Imaging of Diatomic Sulfur (S2)

    NASA Astrophysics Data System (ADS)

    Frederix, Pim W. J. M.; Yang, Chung-Hsin; Groenenboom, Gerrit C.; Parker, David H.; Alnama, Koutayba; Western, Colin M.; Orr-Ewing, Andrew J.

    2009-09-01

    The photodissociation of diatomic sulfur, S2, in the region of the first dissociation limit is studied with velocity map imaging. Correlated fine structure distributions P(J1,J2) for the two S(3PJ) fragments are determined at selected photolysis wavelengths. Image analysis of the speed distributions of the atomic fragments following product-state-specific detection results in a revision of the bond energy to D0 = 35636.9 ± 2.5 cm-1 with respect to the lowest rovibrational level. This value arises from reinterpretation of previous spectroscopic data showing onset of predissociation in the B3?u- state, as the measurements presented here demonstrate that the long-range correlation of the excited state invoked as causing the dissociation is S(3P2) + S(3P2) rather than S(3P2) + S(3P1). The wavelength dependence of data for the S(3P2) + S(3P2) channel suggests involvement of photoexcitation through the optically forbidden Herzberg continuum bands in addition to dissociation initiated via the optically allowed B3?u--X3?g- and B''3?u-X3?g- bands. Changes in product recoil velocity angular distributions and atomic angular momentum polarization were also measured as a function of dissociation wavelength. The results are compared with predictions from an adiabatic model for dissociation, which provides a basis for interpretation but does not explain quantitatively the experimental results.

  8. The prevalence of endocrinopathic laminitis among horses presented for laminitis at a first-opinion/referral equine hospital.

    PubMed

    Karikoski, N P; Horn, I; McGowan, T W; McGowan, C M

    2011-10-01

    Endocrinopathic causes of laminitis may be a common underlying causative pathogenesis in first-opinion or field cases presenting with laminitis, as opposed to laminitis produced in inflammatory research models. This study aimed to determine whether evidence of an underlying endocrinopathy was present in horses presented for laminitis to a first-opinion/referral veterinary teaching hospital. A second aim was to compare the signalment of horses and ponies with laminitis with the equine hospital population during the same period. All horses presenting for laminitis at Helsinki University Equine Teaching Hospital, Finland, over a 16-month period were examined for an underlying endocrinopathy. Horses presenting for laminitis were compared with the hospitalized population over the same period. There were 36 horses presented for laminitis, and evidence of endocrinopathy was present in 89%. Of the horses showing an underlying endocrinopathy, one-third had a diagnosis of pituitary pars intermedia dysfunction, and two-thirds showed basal hyperinsulinemia indicative of insulin resistance, without evidence of hirsutism. Phenotypic indicators of obesity were present in 95% of horses with basal hyperinsulinemia without hirsutism. Compared with the hospital population during the same period, horses with laminitis associated with an underlying endocrinopathy were significantly older and more likely to be pony breeds. Our data support that endocrine testing should be performed on all cases of laminitis that do not have a clear inflammatory or gastrointestinal origin. PMID:21696910

  9. 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.

  10. Compression after impact of thin composite laminates

    Microsoft Academic Search

    S. Sanchez-Saez; E. Barbero; R. Zaera; C. Navarro

    2005-01-01

    The damage tolerance of various lay-ups of thin carbon\\/epoxy laminates (1.6–2.2 mm thick) is examined by compression after impact (CAI) tests, using a new testing device which adapts to the thicknesses of the specimens and does not require tabs nor any modification of the specimen geometry. The compression stress state was not modified by the presence of the device, as

  11. Hypervelocity impact on laminate composite panels

    Microsoft Academic Search

    V. V. Silvestrov; A. V. Plastinin; N. N. Gorshkov

    1995-01-01

    Phenomenological results on the damage of flat glass-, aramid- and carbon-fiber reinforced epoxy laminated composites under the impact of steel and glass projectiles at velocity up to 8–11 km\\/s are presented. The damage of composite panels under hypervelocity impact is shown to differ significally from that observed for elastoplastic materials. However, it is shown that a number of qualititative results

  12. 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.

  13. Harmonic Currents of Finite Energy and Laminations

    Microsoft Academic Search

    John-Erik Fornaess; Nessim Sibony

    2004-01-01

    We introduce, on a complex Kahler manifold (M,\\\\omega), a notion of energy for harmonic currents of bidegree (1,1). This allows us to define $\\\\int T \\\\wedge T \\\\wedge \\\\omega^{k-2},$ for positive harmonic currents. We then show that for a lamination with singularities of a compact set in P^2 there is a unique positive harmonic current which minimizes energy. If X

  14. Board level reliability for laminate CSP

    Microsoft Academic Search

    Aluto Yoshida; Isao Kudo; Curtis Hart; Julian Partridge

    1998-01-01

    An experiment was conducted to determine card assembly reliability of 0.8 mm laminate chip scale packages (CSPs) on FR4 card material. Accelerated temperature cycle tests (TCT) and card-bending tests were conducted to determine the optimum size and type of pad for card assemblies. Toshiba supplied the CSPs for this study. The CSPs were 177 I\\/O 13 mm×13 mm overmolded packages

  15. Thermo-mechanical response predictions for metal matrix composite laminates

    NASA Technical Reports Server (NTRS)

    Aboudi, J.; Hidde, J. S.; Herakovich, C. T.

    1991-01-01

    An analytical micromechanical model is employed for prediction of the stress-strain response of metal matrix composite laminates subjected to thermomechanical loading. The predicted behavior of laminates is based upon knowledge of the thermomechanical response of the transversely isotropic, elastic fibers and the elastic-viscoplastic, work-hardening matrix. The method is applied to study the behavior of silicon carbide/titanium metal matrix composite laminates. The response of laminates is compared with that of unidirectional lamina. The results demonstrate the effect of cooling from a stress-free temperature and the mismatch of thermal and mechanical properties of the constituent phases on the laminate's subsequent mechanical response. Typical results are presented for a variety of laminates subjected to monotonic tension, monotonic shear and cyclic tensile/compressive loadings.

  16. Tailored metal matrix laminates for high-temperature performance

    NASA Technical Reports Server (NTRS)

    Morei, Michael R.; Saravanos, Dimitris A.; Chamis, C. C.

    1992-01-01

    A multi-objective tailoring methodology is presented to maximize stiffness and load carrying capacity of a metal matrix cross-ply laminated at elevated temperatures. The fabrication process and fiber volume ratio are used as the design variables. A unique feature is the concurrent effects from fabrication, residual stresses, material nonlinearity, and thermo-mechanical loading on the laminate properties at the post-fabrication phase. For a (0.90) (sub s) graphite/copper laminate, strong coupling was observed between the fabrication process, laminate characteristics, and thermo-mechanical loading. The multi-objective tailoring was found to be more effective than single objective tailoring. Results indicate the potential to increase laminate stiffness and load carrying capacity by controlling the critical parameters of the fabrication process and the laminate.

  17. 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.

  18. 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.

  19. Size of Dominant Diatom Species Can Alter Their Evenness

    PubMed Central

    Sugie, Koji; Suzuki, Koji

    2015-01-01

    Traditionally, biodiversity has often been estimated on the basis of abundance partly due to the need for complicated measurements of biomass. Here, we conducted robust measurements of the community composition and of the size structure of diatoms in the North Pacific to evaluate the importance of biomass on the biodiversity. We found that the two most useful evenness indices increased in most cases where small species were numerically dominant when calculations were based on biomass compared with those on abundance. Size-abundance spectra of diatoms revealed that numerically dominant small species rarely dominated in terms of biomass. On the other hand, intermediate to large diatom species generally played a dominant role in terms of biomass in diatom community. The results suggest that the size of the dominant species is a crucial factor in determining the role of diatoms in the ecosystem functioning. Because such size variability can also be observed in other organisms, we need to pay attention to the effect of size structures on biodiversity. PMID:26098838

  20. Epipsammic diatoms in streams influenced by urban pollution, São Carlos, SP, Brazil.

    PubMed

    Bere, T; Tundisi, J G

    2010-11-01

    Epipsammic diatoms have important implications for ecosystem processes in lotic environments. Most of the studies on benthic diatoms concentrate on epilithic diatoms and very little is known about epipsammic diatoms. The objective of this study was to assess epipsammic diatom communities in streams in relation to environmental conditions. Epipsammic diatoms and water quality sampling was done at 7 sites during summer base flow period (2008). Forward stepwise multiple regression and canonical correspondence analysis (CCA) were used to determine environmental gradients along which species vary with physical and chemical variables. A total of 112 diatom species distributed among 44 genera were recorded. Altitude and the process of eutrophication played a significant role in structuring diatom communities in the study region. PMID:21180895

  1. Tension fatigue analysis and life prediction for composite laminates

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  2. Fracture behavior of thick, laminated graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Harris, C. E.; Morris, D. H.

    1984-01-01

    The effect of laminate thickness on the fracture behavior of laminated graphite epoxy (T300/5208) composites was studied. The predominantly experimental research program included the study of the 0/+ or - 45/90 sub ns and 0/90 sub ns laminates with thickness of 8, 32, 64, 96 and 120 plies and the 0/+ or - 45 sub ns laminate with thickness of 6, 30, 60, 90 and 120 plies. The research concentrated on the measurement of fracture toughness utilizing the center-cracked tension, compact tension and three point bend specimen configurations. The development of subcritical damage at the crack tip was studied nondestructively using enhanced X-ray radiography and destructively using the laminate deply technique. The test results showed fracture toughness to be a function of laminate thickness. The fracture toughness of the 0 + or - 45/90 sub ns and 0/90 sub ns laminates decreased with increasing thickness and asymptotically approached lower bound values of 30 ksi square root of in. (1043 MPa square root of mm and 25 ksi square root of in (869 MPa square root of mm respectively. In contrast to the other two laminates, the fracture toughness of the 0/+ or - 45 sub ns laminate increased sharply with increasing thickness but reached an upper plateau value of 40 ksi square root of in (1390 MPa square root of mm) at 30 plies. Fracture toughness was independent of crack size for both thin and thick laminates for all three laminate types except for the 0/90 sub 2s laminate which spilt extensively. The center cracked tension, three point bend and compact tension specimens gave comparable results.

  3. Mechanical behavior of lightweight thermoplastic fiber–metal laminates

    Microsoft Academic Search

    G. Reyes; H. Kang

    2007-01-01

    Lightweight thermoplastic-based fiber–metal laminates were developed based on self-reinforced polypropylene and glass fiber-reinforced polypropylene composite materials and an aluminum alloy 2024-T3. The laminates were manufactured using a fast one-step cold press manufacturing procedure. The mechanical behavior of the laminates was then investigated under tensile and fatigue loading conditions. The tensile properties of the plain aluminum, the composite materials and the

  4. Near-threshold fatigue crack growth in aluminum composite laminates

    Microsoft Academic Search

    P. B. Hoffman; J. C. Gibeling

    1995-01-01

    One promising method for improving the mechanical properties of particulate MMCs is to laminate the brittle composite with a more ductile component. A system currently being developed at Lawrence Livermore National Laboratory (LLNL) is a multilayer laminate consisting of alternating layers of AA6090\\/SiC\\/25p and more ductile AA5182. In order to further examine the effects of lamination on fatigue crack propagation

  5. Antibacterial performance of colloidal silver-treated laminate wood flooring

    Microsoft Academic Search

    Sumin Kim; Hyun-Joong Kim

    2006-01-01

    In this study both the anti-bacterial properties and strength of cockroach avoidance of laminate wood floorings containing colloidal silver is evaluated. The laminate wood flooring manufactured with the overlay added with resin containing colloidal silver ion showed an antibacterial activity of up to 98.9%. For colloidal silver-treated, laminate wood flooring, the relative avoidance rate was 87±1%. With colloidal silver treatment

  6. Direct actin binding to A- and B-type lamin tails and actin filament bundling by the lamin A tail

    PubMed Central

    Simon, Dan N; Zastrow, Michael S

    2010-01-01

    Nuclear intermediate filament networks formed by A- and B-type lamins are major components of the nucleoskeleton. Lamins have growing links to human physiology and disease including Emery-Dreifuss muscular dystrophy (EDMD), lipodystrophy, cardiomyopathy, neuropathy, cerebellar disorders and segmental accelerated ‘aging’ syndromes. How lamins interact with other nucleoskeletal components, and even the identities of these other components, are open questions. Previous studies suggested lamins might bind actin. We report that the recombinant C-terminal tail domain of human A- and B-type lamins binds directly to purified actin in high-speed pelleting assays. This interaction maps to a conserved Actin Binding site (AB-1) comprising lamin A residues 461–536 in the Ig-fold domain, which are 54% identical in lamin B1. Two EDMD-causing missense mutations (R527P and L530P) in lamin A that are predicted to disrupt the Ig-fold, each reduced F-actin binding by ?66%, whereas the surface-exposed lipodystrophy-causing R482Q mutation had no significant effect. The lamin A tail was unique among lamins in having a second actin-binding site (AB-2). This second site was mapped to lamin A tail residues 564–608, based on actin-binding results for the lamin C tail and internal deletions in the lamin A tail that cause Hutchinson-Gilford Progeria Syndrome (?35, ?50) or restrictive dermopathy (?90). Supporting the presence of two actin-binding sites, recombinant precursor (unmodified) and mature lamin A tails (not C or B1 tails) each bundled F-actin in vitro: furthermore F-actin bundling was reduced 25–40% by the R527P, L530P, ?35 and ?50 mutations, and was abolished by ?90. Unexpectedly, the mature lamin A tail bound F-actin significantly more efficiently than did the prelamin A tail; this suggested unmodified residues 647–664, unique to prelamin A, might auto-inhibit binding to actin (and potentially other partners). These biochemical results suggest direct mechanisms by which lamins, particularly lamin A, might impact the concentration of free actin in the nucleus or pathways including transcription, nuclear export, chromatin remodeling, chromatin movement and nuclear assembly that require nuclear myosin 1c and polymerizable actin. PMID:21327074

  7. The Importance of Scale in Understanding the Natural History of Diatom Communities

    Microsoft Academic Search

    Rex L. Lowe

    \\u000a Diatom communities can be composed of hundreds of different species with unique needs and abilities. Although there is a considerable\\u000a size range amongst species, diatoms are relatively small when considering the size of sympatric aquatic organisms and especially\\u000a considering the size of humans that study diatom ecology. To get a clearer understanding of environmental factors important\\u000a in structuring diatom communities,

  8. Should only live diatoms be used in the bioassessment of small mountain streams?

    Microsoft Academic Search

    Nadezhda Gillett; Yangdong Pan; Christian Parker

    2009-01-01

    It is unclear whether differentiating live and dead diatoms would enhance the accuracy and precision of diatom-based stream\\u000a bioassessment. We collected benthic diatom samples from 25 stream sites in the Northern Oregon Coast ecoregion. We counted\\u000a live diatoms (cells with visible chloroplasts) and then compared the counts with those generated using the conventional method\\u000a (clean counts). Non-metric multidimensional scaling (NMDS)

  9. INVESTIGATION OF CORE CLOSEOUTS IN FIBER-REINFORCED SANDWICH LAMINATES

    E-print Network

    INVESTIGATION OF CORE CLOSEOUTS IN FIBER-REINFORCED SANDWICH LAMINATES by Russell Lee Evertz .............................................................................................................4 Sandwich Theory .....................................................32 Sandwich Termination Effects

  10. 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.

  11. 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.

  12. Circular random motion in diatom gliding under isotropic conditions

    NASA Astrophysics Data System (ADS)

    Gutiérrez-Medina, Braulio; Jiménez Guerra, Andrés; Peña Maldonado, Ana Iris; Covarrubias Rubio, Yadiralia; Viridiana García 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.

  13. 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.

  14. 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.

  15. A microwave digestion technique for the extraction of fossil diatoms from coastal lake and swamp sediments

    Microsoft Academic Search

    Jeffrey F Parr; Kathryn H Taffs

    2004-01-01

    This study provides an introduction to a microwave digestion technique for the extraction of fossil diatoms from sediments. The microwave technique is compared with the standard diatom extraction technique of Battarbee (Diatom analysis. In: Berglund B.E. (ed.), Handbook of Holocene Palaeoecology and Palaeohydrology. John Wiley and Sons) that uses a combination of dilute hydrochloric acid and hydrogen peroxide and the

  16. 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

  17. Influence of light and temperature on the growth rate of estuarine benthic diatoms in culture

    Microsoft Academic Search

    W. Admiraal

    1976-01-01

    Four species of estuarine benthic diatoms: Amphiprora c. f. paludosa W. Smith, Nitzschia c. f. dissipata (Kützing) Grunow, Navicula arenaria Donkin, and Nitzschia sigma (Kützing) W. Smith were grown in unialgal cultures. The growth rates of the diatoms were determined as the rate of increase of the chlorophyll a content of the cultures. The diatoms were cultured at different combinations

  18. Iron oxide nanoparticle encapsulated diatoms for magnetic delivery of small molecules to tumors.

    PubMed

    Todd, Trever; Zhen, Zipeng; Tang, Wei; Chen, Hongmin; Wang, Geoffrey; Chuang, Yen-Jun; Deaton, Kayley; Pan, Zhengwei; Xie, Jin

    2014-02-21

    Small molecules can be co-loaded with iron oxide nanoparticles onto diatoms. With an external magnetic field, the diatoms, after systemic administration, can be attracted to tumors. This study suggests a great potential of diatoms as a novel and powerful therapeutic vehicle. PMID:24424277

  19. Herbicide effects on freshwater benthic diatoms: Induction of nucleus alterations and silica cell wall abnormalities

    Microsoft Academic Search

    T. Debenest; J. Silvestre; M. Coste; F. Delmas; E. Pinelli

    2008-01-01

    Benthic diatoms are well known bio-indicators of river pollution by nutrients (nitrogen and phosphorus). Biological indexes, based on diatom sensitivity for non-toxic pollution, have been developed to assess the water quality. Nevertheless, they are not reliable tools to detect pollution by pesticides. Many authors have suggested that toxic agents, like pesticides, induce abnormalities of the diatom cell wall (frustule). High

  20. 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

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

    USGS Publications Warehouse

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Türke, 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.

  2. 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.

  3. Introduction and Motivation Structural Model for Laminated Glass Beams Conclusions and Outlook of Laminated Glass Structures

    E-print Network

    and Motivation Components of Thin Film Solar Modules back sheet or glass encapsulant electrical conductor thin film layer front glass Reference: Schulze, S.-H.; Pander, M.; Naumenko, K.; Altenbach, H.: AnalysisIntroduction and Motivation Structural Model for Laminated Glass Beams Conclusions and Outlook

  4. Analysis of quasi-periodic pore-network structure of centric marine diatom frustules

    NASA Astrophysics Data System (ADS)

    Cohoon, Gregory A.; Alvarez, Christine E.; Meyers, Keith; Deheyn, Dimitri D.; Hildebrand, Mark; Kieu, Khanh; Norwood, Robert A.

    2015-03-01

    Diatoms are a common type of phytoplankton characterized by their silica exoskeleton known as a frustule. The diatom frustule is composed of two valves and a series of connecting girdle bands. Each diatom species has a unique frustule shape and valves in particular species display an intricate pattern of pores resembling a photonic crystal structure. We used several numerical techniques to analyze the periodic and quasi-periodic valve pore-network structure in diatoms of the Coscinodiscophyceae order. We quantitatively identify defect locations and pore spacing in the valve and use this information to better understand the optical and biological properties of the diatom.

  5. A new method for the determination of absolute abundance of diatoms and other silt-sized sedimentary particles

    Microsoft Academic Search

    Reed P. Scherer

    1994-01-01

    The determination of absolute abundances of diatoms in paleolimnological and paleoceanographic studies is now becoming a routine step in diatom paleoecological investigations. Several distinct methods have been described for establishing absolute diatom abundance. Each of these methods has its own strengths and weaknesses. The most common weakness in diatom preparation methods is the use of aliquot subsampling from an assumed

  6. Neuropathic changes in equine laminitis pain.

    PubMed

    Jones, Emma; Viñuela-Fernandez, Ignacio; Eager, Rachel A; Delaney, Ada; Anderson, Heather; Patel, Anisha; Robertson, Darren C; Allchorne, Andrew; Sirinathsinghji, Eva C; Milne, Elspeth M; MacIntyre, Neil; Shaw, Darren J; Waran, Natalie K; Mayhew, Joe; Fleetwood-Walker, Susan M

    2007-12-01

    Laminitis is a common debilitating disease in horses that involves painful disruption of the lamellar dermo-epidermal junction within the hoof. This condition is often refractory to conventional anti-inflammatory analgesia and results in unremitting pain, which in severe cases requires euthanasia. The mechanisms underlying pain in laminitis were investigated using quantification of behavioural pain indicators in conjunction with histological studies of peripheral nerves innervating the hoof. Laminitic horses displayed consistently altered or abnormal behaviours such as increased forelimb lifting and an increased proportion of time spent at the back of the box compared to normal horses. Electron micrographic analysis of the digital nerve of laminitic horses showed peripheral nerve morphology to be abnormal, as well as having reduced numbers of unmyelinated (43.2%) and myelinated fibers (34.6%) compared to normal horses. Sensory nerve cell bodies innervating the hoof, in cervical, C8 dorsal root ganglia (DRG), showed an upregulated expression of the neuronal injury marker, activating transcription factor-3 (ATF3) in both large NF-200-immunopositive neurons and small neurons that were either peripherin- or IB4-positive. A significantly increased expression of neuropeptide Y (NPY) was also observed in myelinated afferent neurons. These changes are similar to those reported in other neuropathic pain states and were not observed in the C4 DRG of laminitic horses, which is not associated with innervation of the forelimb. This study provides novel evidence for a neuropathic component to the chronic pain state associated with equine laminitis, indicating that anti-neuropathic analgesic treatment may well have a role in the management of this condition. PMID:17935886

  7. The pharmacologic basis for the treatment of endocrinopathic laminitis.

    PubMed

    Durham, Andy

    2010-08-01

    Although the treatment and management of laminitis in the horse requires a holistic and often multidisciplinary approach from the veterinarian, farrier, and nutritionist, this review focuses on pharmacologic interventions that might have prophylactic benefit, specifically in the horse with laminitis as a result of pituitary pars intermedia dysfunction and equine metabolic syndrome. PMID:20699177

  8. Differential quadrature for buckling analysis of laminated plates

    Microsoft Academic Search

    Xinwei Wang

    1995-01-01

    Two new sets of grid points are proposed for applying differential quadrature (DQ) to the analysis of structural problems. The accuracy and convergence of differential quadrature for buckling analysis of laminated plates are discussed in this paper. A variety of buckling problems, including composite laminated plates with various boundary constrains under uniaxial, biaxial, and combined uniaxial and shear loadings, are

  9. Post buckling analysis of smart laminated doubly curved shells

    Microsoft Academic Search

    C. K. Kundu; D. K. Maiti; P. K. Sinha

    2007-01-01

    In the present investigation, the geometrically nonlinear post buckling analysis of piezoelectric laminated doubly curved shells is presented using finite element method. The piezoelectric material is used in the form of layers or patches embedded and\\/or surface bonded on laminated composite shells. The finite element model includes the general geometric nonlinearity due to large deflection. The shell geometry used in

  10. Better Thermal Insulation in Solar-Array Laminators

    NASA Technical Reports Server (NTRS)

    Burger, D. R.; Knox, J. F.

    1984-01-01

    Glass marbles improve temperature control. Modified vacuum laminator for photovoltaic solar arrays includes thermal insulation made of conventional glass marbles. Marbles serve as insulation for temperature control of lamination process at cure temperatures as high as 350 degrees F. Used to replace original insulation made of asbestos cement.

  11. A methodology for the global optimization of laminated composite structures

    Microsoft Academic Search

    N. Zehnder; P. Ermanni

    2006-01-01

    A methodology aimed at the global optimization of real-world laminated composite structures is introduced. It mainly consists of a parameterization scheme on the basis of the physical composition of laminated structures and a flexible and robust optimization engine using Evolutionary Algorithms. The parameterization scheme ensures, that the optimization leads to designs that can be produced easily. The methodology is validated

  12. Applying laminated busbars to enhance DC power distribution systems

    Microsoft Academic Search

    M. Stibgen

    2004-01-01

    The intent of this paper will be an overview of how to design and implement laminated busbars into DC power distribution systems. It will include; electrical, physical and thermal characteristics obtained by utilizing a laminated busbar for DC power distribution. The power density of today's technology requires the power distribution system to play an active role in compacting size while

  13. Finite element formulation of orthotropic piezoceramic patch actuator laminated plates

    Microsoft Academic Search

    Ziya Koray Kusculuoglu; Thomas J. Royston

    2004-01-01

    Constitutive and finite element models of a piezoceramic laminated plate are derived using shear deformation (Mindlin plate) theory for each layer, where constraints are added to ensure the elastic deformation continuity at the interface. The major difference of this study compared to previous studies is that the finite element formulation is applicable to both thin and thick laminated plates with

  14. Evaluation of residual strength of notched fiber metal laminates

    Microsoft Academic Search

    Guocai Wu; Yi Tan; Jenn-Ming Yang

    2007-01-01

    Fiber metal laminates (FML) are a family of hybrid materials consisting of alternating layers of thin metal sheets and fiber-reinforced epoxy prepregs. In contrast to aluminum alloys, the presence of notches in FML causes significant strength reductions. The objective of this study was to evaluate the residual strength of fiber-reinforced metal laminates with a circular open hole. Mechanical testing was

  15. Processing of thermoset prepreg laminate via exposure to microwave radiation

    SciTech Connect

    Paulauskas, F.L. [Oak Ridge National Lab., TN (United States); Meek, T.T. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering

    1994-06-01

    Studies of microwave-assisted curing of neat resins (epoxy) and unidirectional glass and carbon fiber laminates have shown that a substantial reduction in the curing time was obtained. This may be explained by the penetration of microwave energy directly and throughout the laminate with enhancement of the kinetics of the chemical reaction. Results of this work indicate that the microwave assisted curing of glass fiber laminates also shows a substantial reduction of the required curing time. Microwave radiation of 2.45 GHz has been demonstrated to be an acceptable method to cure unidirectional carbon fiber laminates. Also, effective curing of crossply (0/90) laminates through this method was observed when proper rotation of the parts accompanied the curing process. This is in accordance with previous work. Multidirectional carbon fiber/epoxy laminates demonstrate a lack of coupling during the curing process. A direct curing of these laminates was not possible by microwave radiation with the experimental approach used, in agreement with previous work. Nevertheless, a moderate reduction in the curing time of these thin laminates was observed due to hybrid curing.

  16. Thermal buckling of activated shape memory reinforced laminated plates

    Microsoft Academic Search

    Rivka Gilat; Jacob Aboudi

    2006-01-01

    The analysis of thermal buckling of rectangular active laminated composite plates is presented. The plates consist of layers of a unidirectional composite with shape memory alloy fibers embedded in polymeric or metallic matrices. The fibers are activated by a mechanical loading-unloading cycle which is applied to the laminated plate, prior to the application of the thermal loading. Micromechanically established constitutive

  17. Characterisation of fibre metal laminates under thermomechanical loadings

    Microsoft Academic Search

    M. Hagenbeek

    2005-01-01

    Fibre metal laminates, such as Arall or Glare, can offer improved properties compared to monolithic materials. Glare for example shows improved fatigue, residual strength, burn-through, impact and corrosion properties with respect to aluminium 2024, together with a considerable weight reduction and competitive costs. A large research program has proven the technological readiness of Glare and the fibre metal laminate has

  18. 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

  19. A Laminated Track for the Inductrack System: Theory and Experiment

    SciTech Connect

    Post, R F; Hoburg, J F

    2004-01-12

    A laminated structure, composed of stacks of thin conducting sheets, has several advantages over a litz-wire ladder as the ''track'' wherein levitating currents are induced by a permanent magnet array on a moving vehicle. Modeling and experimental results for the laminated track are described and evaluated in this paper.

  20. A Laminated Track for the Inductrack System: Theory and Experiment

    Microsoft Academic Search

    R F Post; J F Hoburg

    2004-01-01

    A laminated structure, composed of stacks of thin conducting sheets, has several advantages over a litz-wire ladder as the ''track'' wherein levitating currents are induced by a permanent magnet array on a moving vehicle. Modeling and experimental results for the laminated track are described and evaluated in this paper.

  1. Genetic optimization of two-material composite laminates

    Microsoft Academic Search

    Laurent Grosset; Satchi Venkataraman; Raphael T. Haftka

    This paper describes the optimization of a composite laminate made from two materials. The use of two materials in the laminates design can offer improved designs, as it is possible to combine the desirable properties of the two materials. In this paper, we consider the use of graphite-epox y, which has high stiffness properties, but is expensive, and glass-epoxy, which

  2. Single sided substrates and packages based on laminate materials

    Microsoft Academic Search

    B. K. Appelt; B. Su; A. S. F. Huang; T. Hsieh; Yi-Shao Lai

    2010-01-01

    Laminate based substrates have traditionally been of two or more layers of metal because thin Cu clad laminate cores (CCL) have not been available, nor was the equipment\\/process technology available to circuitize these CCLs. Concomitantly, the designs on both die and substrate level have always assumed the multi-layer nature of the substrate which allowed for wire crossings by using plated

  3. Semitransparent Organic Photovoltaic Cells with Laminated Top Electrode

    Microsoft Academic Search

    Jung-Yong Lee; Steve T. Connor; Yi Cui; Peter Peumans

    2010-01-01

    We demonstrate semitransparent small molecular weight organic photovoltaic cells using a laminated silver nanowire mesh as a transparent, conductive cathode layer. The lamination process does not damage the underlying solar cell and results in a transparent electrode with low sheet resistance and high optical transmittance without impacting photocurrent collection. The resulting semitransparent phthalocyanine\\/fullerene organic solar cell has a power conversion

  4. Neural Networks in Damage Detection of Composite Laminated Plates

    Microsoft Academic Search

    L. ROSEIRO; U. RAMOS; R. LEAL

    2005-01-01

    In this work a methodology for damage detection on laminated composite plates involving the use of piezoelectric sensors and artificial neural networks is present. The presence of damage in the laminated composite plate leads to changes in its structural characteristics, causing variations in electrical potential of sensors. A feed-forward type neural network, trained by Levenberg-Marquardt algorithm is used in order

  5. 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.

  6. 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.

  7. Bending behavior of general unsymmetric laminates 

    E-print Network

    Danielson, Kent Thomas

    1987-01-01

    xyk (e) are the stresses in the k ply and ~11 ~12 [~j k ~12 22 ~16 26 ') i6 '26 )66 k (9) is the stiffness matrix of the k ply, referred to the plate coor di nate axes. Insertion of equat1ons (4) and (7) 1nto the stra1n energy expression... axay (18a, b, c) Substituting the above 1nto equation (12) and performing the matrix operations gives the following expression for the stra1n energy in a general laminate U = Q]) [ A [au )2 + 2A [au av ) + A [av )2 + 2A [ ? ? + ? ? ] 11 ax 12 ax ay...

  8. Differential Curing In Fiber/Resin Laminates

    NASA Technical Reports Server (NTRS)

    Webster, Charles N.

    1989-01-01

    Modified layup schedule counteracts tendency toward delamination. Improved manufacturing process resembles conventional process, except prepregs partially cured laid on mold in sequence in degree of partial cure decreases from mold side to bag side. Degree of partial cure of each layer at time of layup selected by controlling storage and partial-curing temperatures of prepreg according to Arrhenius equation for rate of gel of resin as function of temperature and time from moment of mixing. Differential advancement of cure in layers made large enough to offset effect of advance bag-side heating in oven or autoclave. Technique helps prevent entrapment of volatile materials during manufacturing of fiber/resin laminates.

  9. 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.

  10. Coupled Deformation Properties of Anti-Symmetrical Laminate Composites

    NASA Astrophysics Data System (ADS)

    Hojo, Masahiro; Hashimoto, Ryosaku; Ogawa, Akinori

    Anti-symmetrical laminate composites exhibit a coupling effect between tensile stress and twisting deformation, and are very attractive as blade materials for aircraft engines. Blades made of anti-symmetrical laminate composites can automatically adjust their stagger angle to a better aerodynamic configuration with changing rotational speed. Thus, the aerodynamic efficiency and stability of aircraft engines can be greatly improved. In this study, the coupled deformation properties of anti-symmetrical laminate composites were evaluated with tensile tests. Two kinds of specimens fabricated from carbon/epoxy laminate composites with different anti-symmetrical stacking sequences were tested. On the basis of the tensile-test results, the anti-symmetrical laminate composites were then used as blade materials. The coupled deformation of the test blades at high rotational speed was evaluated by spin tests and FEM analyses. It was demonstrated that test blades twisted about 4° at 10000rpm.

  11. Near-threshold fatigue crack growth in aluminum composite laminates

    SciTech Connect

    Hoffman, P.B.; Gibeling, J.C. [Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science] [Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

    1995-03-15

    One promising method for improving the mechanical properties of particulate MMCs is to laminate the brittle composite with a more ductile component. A system currently being developed at Lawrence Livermore National Laboratory (LLNL) is a multilayer laminate consisting of alternating layers of AA6090/SiC/25p and more ductile AA5182. In order to further examine the effects of lamination on fatigue crack propagation mechanics and mechanisms, the fatigue crack growth behavior of the aluminum composite laminate developed at LLNL was examined. The laminate and the AA6090/SiC/25p component were studied in the T6 heat treatment condition for subsequent comparison. Fatigue crack surfaces were examined using scanning electron microscopy for further insight into crack growth mechanisms.

  12. Deposition of laminated shale: A field and experimental study

    NASA Astrophysics Data System (ADS)

    Carey, Daniel L.; Roy, David C.

    1985-03-01

    Intermittently laminated shale of the Jemtland Formation in Maine is characterized by thin lenticular silt segregations interlaced with argillaceous and organic material (including graptolites). This shale is thinly interbedded with nonlaminated shale, siltstone, and thicker turbidite graywacke beds. Experiments suggest that the intermittently laminated shale was deposited by silt/clay-laden currents and may have been part of an upward turbidite progression from parallel-laminated silt (>60% silt), through intermittently laminated mud (40 to 60% silt), to nonlaminated mud (20 to 40% silt). Intermittently laminated mud may be produced from silt/clay flows that are: decelerating at a constant silt content, losing silt at constant velocity; or both decelerating and losing silt.

  13. Extracellular Matrix Assembly in Diatoms (Bacillariophyceae)' 1. A Model of Adhesives Based on Chemical Characterization and localization of Polysaccharides from the Marine Diatom Achnanthes longipes and Other Diatoms

    Microsoft Academic Search

    Brandon A. Wustman; Michael R. Cretz; Kyle D. Hoagland

    Extracellular adhesives from the diatoms Achnanthes longipes, Amphora coffeaeformis, Cymbella cisfula, and Cymbella mexicana were characterized by monosaccharide and methylation analysis, lectin-fluorescein isothiocyanate localization, and cytochemical staining. Polysaccharide was the major component of adhesives formed during cell motility, synthesis of a basal pad, and\\/or pro- duction of a highly organized shaft. Hot water-insoluble\\/hot 0.5 M NaHC0,-soluble anionic polysaccharides from A.

  14. Response of epilithic diatom assemblages to urbanization influences

    Microsoft Academic Search

    Peter Newall; Christopher J. Walsh

    2005-01-01

    Urbanization has long been recognized to alter the hydrology, water quality and channel form of waterways. Recently, consideration of urban impacts on waterways has expanded to include assessment of the aquatic biota, generally focusing upon the macroinvertebrate fauna. This study compares the impacts of urbanization on the structure of stream benthic diatom communities in 16 first- and second-order streams in

  15. Theory of rotational relaxation in a diatomic gas

    Microsoft Academic Search

    G. Ia. Gerasimov; V. N. Makarov

    1975-01-01

    A numerical solution was found in the framework of classical mechanics for the problem of energy transfer between translational and rotational degrees of freedom when a diatomic molecule and a structureless particle collide. The results were used in a numerical Monte Carlo calculation of the collision integral which determines the rotational-relaxation time. As an example, the rotational-relaxation time of molecular

  16. Cadmium: A nutrient for the marine diatom Thalassiosira weissflogii

    Microsoft Academic Search

    JENNIFER G. LEE; SAMANTHA B. ROBERTS; FRANÇOIS M. M. MOREL

    1995-01-01

    Although cadmium is known to be very toxic, it exhibits nutrientlike vertical concentration profiles in the open ocean. Recent work has shown that under conditions of zinc limitation, cadmium enhances the growth of the marine diatom Thalassiosira weissflogii. Here, we conclusively demonstrate that Cd is a nutrient for T. weissjlogii at inorganic Zn and Cd concentrations typical of surface seawater,

  17. 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.

  18. Contrasting size evolution in marine and freshwater diatoms

    E-print Network

    carbon cycle and most aquatic ecosystems. Their cell sizes impact carbon sequestration and en- ergy and forming the basis of many aquatic food webs (6). Diatom size distributions greatly influence carbon sequestration efficiency: due to their faster sinking and slower dissolution, large cells export

  19. Experimental Vibrational Zero-Point Energies: Diatomic Molecules

    Microsoft Academic Search

    Karl K. Irikura

    2007-01-01

    Vibrational zero-point energies (ZPEs), as determined from published spectroscopic constants, are derived for 85 diatomic molecules. Standard uncertainties are also provided, including estimated contributions from bias as well as the statistical uncertainties propagated from those reported in the spectroscopy literature. This compilation will be helpful for validating theoretical procedures for predicting ZPEs, which is a necessary step in the ab

  20. Diatomic Cesium in a Diode-Pumped Alkali Laser System

    Microsoft Academic Search

    Jamey Christy; Eric Martinez; Tanner Oakes; Jake Smith; Kendrick Walter

    2008-01-01

    Abstract Diode Pumped Alkali Laser (DPAL) systems combine the positive characteristics of chemical and diode lasers. These systems create a laser that is compact and ecient, while working well at high temperatures and high powers. In conjunction with the Air Force Research Laboratory (AFRL), an attempt was made to improve DPAL technology by using a diatomic alkali metal as a

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

    PubMed

    Cermeño, 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

  2. HISTORICAL PROCESSES CONSTRAIN PATTERNS IN GLOBAL DIATOM DIVERSITY

    Microsoft Academic Search

    Wim Vyverman; Elie Verleyen; Koen Sabbe; Koenraad Vanhoutte; Mieke Sterken; Dominic A. Hodgson; David G. Mann; Steve Juggins; Bart Van de Vijver; Vivienne Jones; Roger Flower; Donna Roberts; Victor A. Chepurnov; Cathy Kilroy; Pieter Vanormelingen; Aaike De Wever

    2007-01-01

    There is a long-standing belief that microbial organisms have unlimited dispersal capabilities, are therefore ubiquitous, and show weak or absent latitudinal diversity gradients. In contrast, using a global freshwater diatom data set, we show that latitudinal gradients in local and regional genus richness are present and highly asymmetric between both hemispheres. Patterns in regional richness are explained by the degree

  3. The paleoclimatology of Lake Baikal: A diatom synthesis and prospectus

    Microsoft Academic Search

    Anson W. Mackay

    2007-01-01

    The paleoclimatic archive held in Lake Baikal sediments is of significant importance, given the lake's position in one of the world's most continental regions where there are few continuous, high quality records spanning the Quaternary. Here I review diatom and associated biogenic silica records from Lake Baikal sediments and provide a paleoclimatic synthesis of changes at various timescales over the

  4. Effect of dissociation on thermodynamic properties of pure diatomic gases

    NASA Technical Reports Server (NTRS)

    Woolley, Harold W

    1955-01-01

    A graphical method is described by which the enthalpy, entropy, and compressibility factor for the equilibrium mixture of atoms and diatomic molecules for pure gaseous elements may be obtained and shown for any dissociating element for which the necessary data exist. Results are given for hydrogen, oxygen, and nitrogen. The effect of dissociation on the heat capacity is discussed briefly.

  5. Bicarbonate transport and extracellular carbonic anhydrase in marine diatoms.

    PubMed

    Martin, Cheryl L; Tortell, Philippe D

    2008-05-01

    In this article, we present new laboratory results examining the relative importance of HCO(-)(3) transport and extracellular carbonic anhydrase (eCA) in 17 marine diatom species. We observed significant variability in both HCO(-)(3) transport and eCA expression across a range of diatom species with different cell morphologies. All species we examined took up HCO(-)(3) through a direct transport mechanism, with the fraction of HCO(-)(3) transport ranging from 40 to 95% of total C uptake. eCA expression also varied significantly, with catalytic enhancement factors ranging approximately 10-fold among species. There was a significant positive correlation between HCO(-)(3) transport and eCA expression among the test species. However, neither HCO(-)(3) transport nor eCA expression was significantly correlated to cell growth rates or surface area to volume ratios. We did observe weak positive trends between the ratio of C demand:supply and HCO(-)(3) utilization/eCA expression, but these were not statistically significant. We are thus unable to provide a mechanistic explanation for the apparent variability in HCO(-)(3) transport and eCA expression in marine diatoms. This variability may, nonetheless, have important implications for the physiological ecology of oceanic diatoms. PMID:18298417

  6. Infrared Spectroscopy of Diatomic Molecules — a Fractional Calculus Approach

    NASA Astrophysics Data System (ADS)

    Herrmann, Richard

    2013-03-01

    The eigenvalue spectrum of the fractional quantum harmonic oscillator is calculated numerically, solving the fractional Schrödinger equation based on the Riemann and Caputo definition of a fractional derivative. The fractional approach allows a smooth transition between vibrational and rotational type spectra, which is shown to be an appropriate tool to analyze IR spectra of diatomic molecules.

  7. Statistical quantum studies on insertion atom-diatom reactions

    Microsoft Academic Search

    Tomás González-Lezana

    2007-01-01

    The study of insertion atom-diatom reactions is usually complicated by the existence of deep potential wells between reactants and products. The large number of bound and resonance states to be properly described makes exact quantum mechanical calculations extremely demanding in terms of numerical effort. In this type of collision, the process proceeds via the formation of an intermediate complex of

  8. Diatoms: unique eukaryotic extremophiles providing insights into planetary change

    NASA Astrophysics Data System (ADS)

    Kociolek, J. P.

    2007-09-01

    The diatoms (Division Bacillariophyta) are aquatic, pigmented single-celled photosynthetic eukaryotes. They are a major component of the food chain in marine, estuarine and freshwater ecosystems. These diploid organisms have the ability to take dissolved silica out of the water column, and use it to create their cell walls. The taxonomy and classification system for the group is based to a large part on cell wall symmetry, as well as the number, type, position and organization of the many perforations in the glass. As a group, diatoms are found in almost every water type of water body around the globe, including a wide range of extreme environments. Individual species, however, have limited distributions and ecological requirements. Preservation of the glass cell walls in sedimentary basins has left nearly a 120 million year record. Species-related distributions, and well-preserved record make diatoms an excellent tool for environmental reconstruction and monitoring. New research on diatoms includes applications to conservation biology, astrobiology, nanotechnology, and biofuels.

  9. Diatom Proteomics Reveals Unique Acclimation Strategies to Mitigate Fe Limitation

    PubMed Central

    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

  10. 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.

  11. 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.

  12. Micromechanical modeling of composite plies and laminates

    NASA Astrophysics Data System (ADS)

    Srinivas, Mullahalli V.

    After, fabrication or in service, certain metal and ceramic matrix laminates may exhibit extensive de-cohesion, such as de-bonding and sliding at fiber-matrix interfaces. The de-cohesion induced changes on overall response and on redistribution of local stress and deformation fields is analyzed here. A finite element analysis of an unit cell model of a fibrous ply is used to obtain energy release rates of the interface cracks and local stress fields. The unit cell results along with observed experimental behavior are exploited in modeling the local de-bonding problems. The effect of de-bonding on local stress is simulated by an equivalent eigenstrain introduced in the bonded fiber. Transformation field analysis (40) is used in evaluating the equivalent eigenstrain and also the overall field. Simple relations for change in potential energy due to de-cohesion are obtained using Colonetti's theorem (28). A comparison of these energy results with the finite element unit cell results show very good agreement. Another problem addressed is that of gradual or progressive de-bonding, where the interfacial strength at individual fibers is distributed within a certain range. The corresponding overall response with gradual de-bonding is studied. The composite is modeled as a three phase system with matrix, bonded fibers and the de-bonded or partly de-bonded fibers using differential scheme and Mori-Tanaka assumptions. The interfacial stress in the bonded fiber is used in the Weibull's probability function to form the de-bonding criterion. The model is incorporated into the laminated plate theory for incremental evaluation of the local fields along a given overall loading path. Applications indicate that the interfacial strength plays a significant role in overall response and the stiffness reduces with gradual de-bonding. Initial failure maps similar to Dvorak et al. (44, 45, 38, 39) are constructed for brittle composite laminates under combined in-plane loads. The maps are derived from local stresses in the fiber, matrix and at their interfaces, and from selected magnitudes of the respective strengths. These maps indicate the damage free load range of the laminate and the source of likely initial failure by fiber or matrix cracking, or by fiber de-bonding. The insight into the events occurring after exceeding one of the de-bonding branches is obtained by drawing subsequent failure maps. Assuming that a few fibers de-bond after reaching one of the de-bonding branches, the stress states are recalculated near the de-bonded fibers using the three phase model to obtain a new set of branches. An application to SiC/SiC laminates with unidirectional and (0/90)sb{s} layups shows that the initial de-bonding leads to the immediate matrix radial cracking. A thick-walled composite cylinder consisting of many different cylindrically orthotropic layers, loaded by uniform, axisymmetric surface tractions and by piecewise uniform eigenstrains in layers is analyzed. A theoretical framework is established for evaluation of internal stress fields with mechanical and transformation influence functions. A particular fabrication process that utilizes fiber prestress as a source of the layer eigenstrain is analyzed. An optimal distribution of prestress is obtained for a desired level of hoop and axial residual stresses in the cylinder wall. It is shown that the application of a high fiber prestress in the form of constant, linear or parabolic distribution along the cylinder wall can be harmful as it may generate very high hoop stress gradients.

  13. DELAMINATION DETECTION IN FIBER METAL LAMINATES USING THE MODE CONVERSION OF LAMB WAVES

    E-print Network

    Paris-Sud XI, Université de

    DELAMINATION DETECTION IN FIBER METAL LAMINATES USING THE MODE CONVERSION OF LAMB WAVES Yoji Okabe1@iis.u-tokyo.ac.jp ABSTRACT Fiber metal laminates (FMLs) consisting of FRP composites and thin metal foils are gathering to aircrafts, fiber metal laminates (FMLs) are gathering attention [1]. Since the FMLs are hybrid laminates

  14. Role of nuclear Lamin A/C in cardiomyocyte functions.

    PubMed

    Carmosino, Monica; Torretta, Silvia; Procino, Giuseppe; Gerbino, Andrea; Forleo, Cinzia; Favale, Stefano; Svelto, Maria

    2014-10-01

    Lamin A/C is a structural protein of the nuclear envelope (NE) and cardiac involvement in Lamin A/C mutations was one of the first phenotypes to be reported in humans, suggesting a crucial role of this protein in the cardiomyocytes function. Mutations in LMNA gene cause a class of pathologies generically named 'Lamanopathies' mainly involving heart and skeletal muscles. Moreover, the well-known disease called Hutchinson-Gilford Progeria Syndrome due to extensive mutations in LMNA gene, in addition to the systemic phenotype of premature aging, is characterised by the death of patients at around 13 typically for a heart attack or stroke, suggesting again the heart as the main site sensitive to Lamin A/C disfunction. Indeed, the identification of the roles of the Lamin A/C in cardiomyocytes function is a key area of exploration. One of the primary biological roles recently conferred to Lamin A/C is to affect contractile cells lineage determination and senescence. Then, in differentiated adult cardiomyocytes both the 'structural' and 'gene expression hypothesis' could explain the role of Lamin A in the function of cardiomyocytes. In fact, recent advances in the field propose that the structural weakness/stiffness of the NE, regulated by Lamin A/C amount in NE, can 'consequently' alter gene expression. PMID:25055884

  15. In-plane vibration of slightly curved laminated composite beams

    NASA Astrophysics Data System (ADS)

    Qatu, M. S.

    1992-12-01

    A complete set of equations for the free and forced vibration analysis of laminated composite beams of shallow curvature is presented. The beam is assumed to be vibrating in its plane. These equations are shown to be consistent by variational derivation. Natural frequencies for simply supported curved beams are obtained by exact solutions. The Ritz method with algebraic polynomials is used to obtain approximate solutions for arbitrary boundary conditions. Natural frequencies for completely free and cantilevered curved beams are presented as examples. Extension-bending coupling due to lamination is distinguished from that due to curvature. Effects of curvature, material orthotropy and lamination sequence on the natural frequencies are studied.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Compression failure of angle-ply laminates

    NASA Technical Reports Server (NTRS)

    Peel, L. D.; Hyer, M. W.; Shuart, M. J.

    1992-01-01

    Test results from the compression loading of (+ or - Theta/ - or + Theta)(sub 6s) angle-ply IM7-8551-7a specimens, 0 less than or = Theta less than or = 90 degs, are presented. The observed failure strengths and modes are discussed, and typical stress-strain relations shown. Using classical lamination theory and the maximum stress criterion, an attempt is made to predict failure stress as a function of Theta. This attempt results in poor correlation with test results and thus a more advanced model is used. The model, which is based on a geometrically nonlinear theory, and which was taken from previous work, includes the influence of observed layer waviness. The waviness is described by the wave length and the wave amplitude. The theory is briefly described and results from the theory are correlated with test results. It is shown that by using levels of waviness observed in the specimens, the correlation between predictions and observations is good.

  2. Stability optimization of laminated composite plates

    NASA Technical Reports Server (NTRS)

    Hirano, Y.

    1980-01-01

    The optimum design of plates with orthotropic layers under axial compression and shear is discussed. The plates considered are the laminates of N orthotropic layers whose principal material axes coincide with the plate axes. Each layer is assumed to have the same thickness and an equal number of fibers in the direction of + alpha sub i and - alpha sub i with respect to the plate axis. The fiber directions which give the highest axial buckling stress and the highest shear buckling stress are found by utilizing a mathematical optimization technique for various aspect ratios of the plates. Inhomogeneity in the direction of the plate thickness (stacking sequence) is taken into account in this analysis.

  3. 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.

  4. The Creep of Laminated Synthetic Resin Plastics

    NASA Technical Reports Server (NTRS)

    Perkuhn, H

    1941-01-01

    The long-time loading strength of a number of laminated synthetic resin plastics was ascertained and the effect of molding pressure and resin content determined. The best value was observed with a 30 to 40 percent resin content. The long-time loading strength also increases with increasing molding pressure up to 250 kg/cm(exp 2); a further rise in pressure affords no further substantial improvement. The creep strength is defined as the load which in the hundredth hour of loading produces a rate of elongation of 5 X 10(exp -4) percent per hour. The creep strength values of different materials were determined and tabulated. The effect of humidity during long-term tests is pointed out.

  5. Extracellular Matrix Assembly in Diatoms (Bacillariophyceae) (I. A Model of Adhesives Based on Chemical Characterization and Localization of Polysaccharides from the Marine Diatom Achnanthes longipes and Other Diatoms).

    PubMed Central

    Wustman, B. A.; Gretz, M. R.; Hoagland, K. D.

    1997-01-01

    Extracellular adhesives from the diatoms Achnanthes longipes, Amphora coffeaeformis, Cymbella cistula, and Cymbella mexicana were characterized by monosaccharide and methylation analysis, lectin-fluorescein isothiocyanate localization, and cytochemical staining. Polysaccharide was the major component of adhesives formed during cell motility, synthesis of a basal pad, and/or production of a highly organized shaft. Hot water-insoluble/hot 0.5 M NaHCO3-soluble anionic polysaccharides from A. longipes and A. coffeaeformis adhesives were primarily composed of galactosyl (64-70%) and fucosyl (32-42%) residues. In A. longipes polymers, 2,3-, t-, 3-, and 4-linked/substituted galactosyl, t-, 3-, 4-, and 2-linked fucosyl, and t- and 2-linked glucuronic acid residues predominated. Adhesive polysaccharides from C. cistula were EDTA-soluble, sulfated, consisted of 83% galactosyl (4-, 4,6-, and 3,4-linked/substituted) and 13% xylosyl (t-, 4f/5p-, and 3p-linked/substituted) residues, and contained no uronosyl residues. Ulex europaeus agglutinin uniformly localized [alpha](1,2)-L-fucose units in C. cistula and Achnanthes adhesives formed during motility and in the pads of A. longipes. D-Galactose residues were localized throughout the shafts of C. cistula and capsules of A. coffeaeformis. D-Mannose and/or D-glucose, D-galactose, and [alpha](t)-L-fucose residues were uniformly localized in the outer layers of A. longipes shafts by Cancavalia ensiformis, Abrus precatorius, and Lotus tetragonolobus agglutinin, respectively. A model for diatom cell adhesive structure was developed from chemical characterization, localization, and microscopic observation of extracellular adhesive components formed during the diatom cell-attachment process. PMID:12223660

  6. Spectroscopy of Vibrational States in Diatomic Iodine Molecules

    NASA Astrophysics Data System (ADS)

    Mulholland, Mary; Harrill, Charles H.; Smith, R. Seth

    2015-04-01

    This project is focused on understanding the vibrational structure of iodine, which is a homonuclear diatomic molecule. A 20 mW, 532 nm cw diode laser was used to selectively excite neutral iodine molecules to a higher energy electronic state. By performing spectroscopy on the transitions from this state to a lower energy electronic state, the data only showed those vibrational bands which connect the two electronic states. Since a number of vibrational levels are populated in the higher energy electronic state, the transitions to all of the allowed vibrational levels in the lower energy electronic state provided sufficient data to determine the vibrational structures of both states. Emission spectra were collected with an Ocean Optics USB4000 Compact CCD Spectrometer. The spectrometer had a range of 500 - 770 nm with a resolution of approximately 0.5 nm and was sensitive enough to resolve the vibrational states in diatomic iodine molecules. The results were compared to a simple harmonic oscillator model.

  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. A test on different aspects of diatom processing techniques

    Microsoft Academic Search

    Saúl Blanco; Irene Álvarez; Cristina Cejudo

    2008-01-01

    A factorial experiment was carried out in order to assess the effects of four treatment steps in diatom processing techniques\\u000a (the quantity of hydrogen peroxide added to the sample, the time allowed to the digestion reaction, the use of centrifugation\\u000a and the method used to settle the frustules onto the coverslip) on different aspects of the quality of the resulting

  9. Classical Theory of Rotational Relaxation of Diatomic Molecules

    Microsoft Academic Search

    George C. Berend; Sidney W. Benson

    1967-01-01

    The classical equations of motion of colliding diatomic molecules are solved rigorously in two dimensions to obtain the energy transferred to the internal degrees of freedom during collision. The model considers up to four atoms bound by six atom-centered Morse potentials. The effect of varying range parameters is noted. The relaxation of H2 with He and H2 collision partners, D2

  10. Overlap Polarizability and Covalency in Diatomic Molecules and Europium Complexes

    Microsoft Academic Search

    R. Q. Albuquerque; O. L. Malta

    \\u000a The concepts of overlap polarizability and ionic specific valence have been initially applied to the series of alkali halides\\u000a RX, where R = Li, Na and K, and X = F, Cl, Br and I. The values of overlap polarizability for this diatomic series have been\\u000a calculated and a new covalency scale based on this quantity has been proposed, showing

  11. Condensed-matter energetics from diatomic molecular spectra

    NASA Technical Reports Server (NTRS)

    Kim, In H.; Jeanloz, Raymond; Jhung, Kyu S.

    1993-01-01

    Analyses of molecular spectra and compression data from crystals show that a single function successfully describes the dependence on interatomic separation of both the potential energy of diatomic molecules and the cohesive binding energy of condensed matter. The empirical finding that one function describes interatomic energies for such diverse forms of matter and over a wide range of conditions can be used to extend condensed-matter equations of state but warrants further theoretical study.

  12. Nuclear-spin-dependent parity violation in diatomic molecular ions

    NASA Astrophysics Data System (ADS)

    Borschevsky, A.; Iliaš, M.; Dzuba, V. A.; Beloy, K.; Flambaum, V. V.; Schwerdtfeger, P.

    2012-11-01

    Nuclear-spin-dependent (NSD) parity-violating (PV) effects can be strongly enhanced in diatomic molecules containing heavy atoms. Future measurements are anticipated to provide nuclear anapole moments and strength constants for PV nuclear forces. In light molecules, the NSD electroweak electron-nucleus interaction may also be detected. Here we calculate NSD PV effects for molecular ions. Our calculations are motivated by rapid developments in trapping techniques for such systems at low temperatures.

  13. Nuclear envelope remodelling during human spermiogenesis involves somatic B-type lamins and a spermatid-specific B3 lamin isoform.

    PubMed

    Elkhatib, Razan; Longepied, Guy; Paci, Marine; Achard, Vincent; Grillo, Jean-Marie; Levy, Nicolas; Mitchell, Michael J; Metzler-Guillemain, Catherine

    2015-03-01

    The nuclear lamina (NL) is a filamentous protein meshwork, composed essentially of lamins, situated between the inner nuclear membrane and the chromatin. There is mounting evidence that the NL plays a role in spermatid differentiation during spermiogenesis. The mouse spermatid NL is composed of the ubiquitous lamin B1 and the spermatid-specific lamin B3, an N-terminally truncated isoform of lamin B2. However, nothing is known about the NL in human spermatids. We therefore investigated the expression pattern and localization of A-type lamins (A, C and C2) and B-type lamins (B1, B2 and B3) during human spermiogenesis. Here, we show that a lamin B3 transcript is present in human spermatids and that B-type lamins are the only lamins detectable in human spermatids. We determine that, as shown for their mouse counterparts, human lamin B3, but not lamin B2, induces strong nuclear deformation, when ectopically expressed in HeLa cells. Co-immunofluorescence revealed that, in human spermatids, B-type lamins are present at the nuclear periphery, except in the region covered by the acrosome, and that as the spermatid matures the B-type lamins recede towards the posterior pole. Only lamin B1 remains detectable on 33-47% of ejaculated spermatozoa. On spermatozoa selected for normal head density, however, this fell to <6%, suggesting that loss of the NL signal may be linked to complete sperm nucleus compaction. The similarities revealed between lamin expression during human and rodent spermiogenesis, strengthen evidence that the NL and lamin B3 have conserved functions during the intense remodelling of the mammalian spermatid nucleus. PMID:25477337

  14. On the description of anisotropic damage in composite laminates

    NASA Astrophysics Data System (ADS)

    Wei, Yang; Boehler, J. P.

    1991-11-01

    A general anisotropic damage theory of cracked laminates is formulated here. The deformation of composite laminates is composed of matrix elastic strains, pseudo-elastic damage strains due to cracking and permanent damage strains due to interlaminar slip. The surface of damage initiation is constructed according to the concept of linear elastic fracture mechanics for the virgin material. After the initial damage, a pesudo-elastic damage can be used to describe the damage behaviour if interlaminar slip is negligible. Damage evolution, load induced anisotropy and interlaminar intralaminar interaction for composite laminates are examined; the latter can perturb the normality structure of damage strain rate. Explicit expressions are given for pseudo-elastic (or secant) moduli of the damaging composite laminates, under a non-interacting assumption imposed on the cracks between different families.

  15. Current concepts on the pathophysiology of pasture-associated laminitis.

    PubMed

    Geor, Raymond J

    2010-08-01

    Epidemiologic studies indicate that most laminitis cases occur in horses and ponies kept at pasture, hence the term 'pasture-associated laminitis'. Clinical cases of laminitis most often occur under conditions that favor accumulation of rapidly fermentable nonstructural carbohydrates (fructans, simple sugars, or starches) in pasture, and animals with an equine metabolic syndrome (EMS) phenotype (insulin resistance, abnormal insulin dynamics, +/- obesity) seem to be at highest risk for developing the condition. Although the mechanisms linking consumption of pasture forage with development of lamellar failure have not been fully elucidated, a systemic inflammatory response that accompanies hindgut carbohydrate overload likely initiates lamellar inflammatory events (including infiltration and activation of leukocytes) that contribute to destruction of lamellar epithelium and extracellular matrix. This article reviews current knowledge on the epidemiology and risk factors for pasture-associated laminitis, including the role of forage carbohydrates and metabolic/endocrine predispositions, and also discusses the pathophysiology of this condition. PMID:20699174

  16. 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.

  17. 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...

  18. Design of laminated composite plates for maximum shear buckling loads

    SciTech Connect

    Chang, R.R.; Chu, K.H.; Kam, T.Y. [National Chiao Tung Univ., Hsin Chu (Taiwan, Province of China). Dept. of Mechanical Engineering

    1993-12-01

    The optimal lamination arrangements of laminated composite plates with maximum shear buckling loads are studied via a multi-start global optimization technique. A previously proposed shear deformable finite element is used to evaluate the positive and negative shear buckling loads of laminated composite plates in the optimal design process. Optimal lay-ups of thin as well as moderately thick composite plates with global maximum positive or negative shear buckling loads are determined utilizing the multi-start global optimal design technique. A number of examples of the optimal shear buckling design of symmetrically and antisymmetrically laminated composite plates with various material properties, length-to-thickness ratios, aspect ratios and different numbers of layer groups are given to illustrate the trends of optimal layer orientations of the plates. Since the existence of in-plane axial force is possible, the effects of axial compressive load on the optimal layer orientations for maximum shear buckling load are also investigated.

  19. Controlling Performance of Laminated Composites Using Piezoelectric Materials 

    E-print Network

    Hasan, Zeaid

    2012-02-14

    ) and piezoelectric fiber composites as actuators for controlling deformation in composite laminates; this study focuses on bending deformation. The purpose is to minimize unwanted deformation, such as the one due to hygrothermal effect, by applying counter...

  20. Characterization of delamination onset and growth in a composite laminate

    NASA Technical Reports Server (NTRS)

    Obrien, T. K.

    1981-01-01

    The onset and growth of delaminations in unnotched (+ or - 30/+ or - 30/90/90 bar) sub S graphite epoxy laminates is described quantitatively. These laminates, designed to delaminate at the edges under tensile loads, were tested and analyzed. Delamination growth and stiffness loss were monitored nondestructively. Laminate stiffness decreased linearly with delamination size. The strain energy release rate, G, associated with delamination growth, was calculated from two analyses. A critical G for delamination onset was determined, and then was used to predict the onset of delaminations in (+45 sub n/-45 sub n/o sub n/90 sub n) sub s (n=1,2,3) laminates. A delamination resistance curve (R curve) was developed to characterize the observed stable delamination growth under quasi static loading. A power law correlation between G and delamination growth rates in fatigue was established.

  1. 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.

  2. 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.

  3. 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.

  4. Controlling Performance of Laminated Composites Using Piezoelectric Materials

    E-print Network

    Hasan, Zeaid

    2012-02-14

    ) and piezoelectric fiber composites as actuators for controlling deformation in composite laminates; this study focuses on bending deformation. The purpose is to minimize unwanted deformation, such as the one due to hygrothermal effect, by applying counter...

  5. 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.

  6. 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.

  7. Paleoenvironmental impact of volcanic eruptions indicated by diatoms

    SciTech Connect

    Brant, L.A.; Bahls, L.L.

    1985-01-01

    Cores of postglacial sediment obtained from small ponds/marshes in west central Montana include several tephra layers representing the series of eruptions of Glacier Peak of about 11,200 years B.P. and of Mount Mazama of about 6600 years B.P. The sediment consists of a basal unit of rock flour overlain by diatomite and other biogenic sediment. Analysis of the palynoflora and the diverse diatom flora indicate that the water was very low in dissolved solid and slightly acid from the time of the beginning of biogenic sedimentation until the present except for times immediately following deposition of each of the two layers of Glacier Peak tephra. Large numbers of Navicula simplex Krasske occur immediately above each of these layers of tephra. This halophilous and alkaliphilous diatom species indicates a short-term change in the chemistry of the pond. After a short period, the solutes carried to the pond by the tephra were washed out of the system allowing it to return to its normal condition, and the halophilous species disappeared. No occurrence of such indicator species was found associated with the younger Mazama tephra. The diatom flora at this site appears to have recorded a paleoenvironmental impact of the eruptions of Glacier Peak hundreds of kilometers from the volcano.

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

    NASA Astrophysics Data System (ADS)

    Palastro, J. P.; Antonsen, T. M., Jr.; Pearson, A.

    2011-07-01

    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 O2 and N2, 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.

  9. Substratum adhesion and gliding in a diatom are mediated by extracellular proteoglycans

    Microsoft Academic Search

    Jan L. Lind; Kirsten Heimann; Elizabeth A. Miller; Catherine van Vliet; Nicholas J. Hoogenraad; Richard Wetherbee

    1997-01-01

    .   Diatoms are unicellular microalgae encased in a siliceous cell wall, or frustule. Pennate diatoms, which possess bilateral\\u000a symmetry, attach to the substratum at a slit in the frustule called the raphe. These diatoms not only adhere, but glide across\\u000a surfaces whilst maintaining their attachment, secreting a sticky mucilage that forms a trail behind the gliding cells. We\\u000a have raised

  10. 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

  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. Equine laminitis: a journey to the dark side of venous.

    PubMed

    Robertson, Tom P; Bailey, Simon R; Peroni, John F

    2009-06-15

    Equine laminitis is a crippling condition that continues to defy repeated efforts to delineate the precise mechanisms involved and develop effective therapeutic strategies for use in the clinic. In this article, the possible role of dysfunction of the laminar vasculature is discussed, with particular emphasis on the venous side of the laminar microvasculature and the possible role(s) that metabolic syndrome and thrombosis may play in the dysfunction observed in the laminar microvasculature during the development of laminitis. PMID:19110318

  13. Apparent strength scaling in continuous fiber composite laminates

    Microsoft Academic Search

    J. Andre Lavoie; Costas Soutis; John Morton

    2000-01-01

    The tensile strength of the 0° plies within different cross-ply and quasi-isotropic laminates of varying size and stacking sequence has been investigated. For those lay-ups having failure confined to the gauge section, no size effect was observed in the strength of 0° plies. In laminates exhibiting a size versus strength relationship, failures were found to occur in the gauge section

  14. THERMAL BUCKLING OF THICK ANTISYMMETRIC ANGLE-PLY LAMINATES

    Microsoft Academic Search

    T. R. Tauchert

    1987-01-01

    The buckling behavior of moderately thick antisymmetric angle-ply laminates that are simply supported and subject to a uniform temperature rise is analyzed. Transverse shear deformation is accounted for by employing the thermoelastic version of the Reissner-Mindlin theory. Results for the classical thin-plate theory are obtained as a special case. Numerical results are presented for fiber-reinforced laminates and show the effects

  15. Computational Models of Laminated Glass Plate under Transverse Static Loading

    Microsoft Academic Search

    Ivelin V. Ivanov; Dimitar S. Velchev; Tomasz Sadowski; Marcin Kne?

    \\u000a Laminated glass with Polyvinyl Butyral (PVB) interlayer became a popular safety glass for aircraft windows, architectural\\u000a and automotive glazing applications. The very soft interlayer, bonding the glass plates, however, has negligible normal stress\\u000a in transverse loading and it resists mainly by shear stress. The classical laminate theory obeying the principle of the straight\\u000a normals remaining straight is not valid for

  16. Parametric instability of twisted cross-ply laminated panels

    Microsoft Academic Search

    A. V. Asha; Shishir Kumar Sahu

    2011-01-01

    The present paper deals with the study of the vibration, buckling and parametric instability characteristics of general laminated cross-ply pre-twisted cantilever flat and curved panels. The effects of angles of pre-twist, aspect ratio, static load factor, and the lamination parameters of the cross-ply twisted curved panels on the principal instability regions are studied using Bolotin?s approach. An eight-noded isoparametric quadratic

  17. Matrix cracking and bending stiffness reduction in composite laminates 

    E-print Network

    Frailey, James Alan

    1988-01-01

    MATRIX CRACKING AND BENDING STIFFNESS REDUCTION IN COAIPOSITE LAMINATES A Thesis by JAMES ALAN FRAILEY Submitted to the Office of Graduate Studies of Texas AgcM University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE December 1988 Major Subject: Aerospace Engineering MATRIX CRACKING AND BENDING STIFFNESS REDUCTION IN COMPOSITE LAMINATES A Thesis by JAMES ALAN FRAILEY Approved as to style and content by: A. L. High mith (Chair of Committee) W. E...

  18. 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

  19. Impact Damage Mechanisms in Fiber-Metal Laminates

    Microsoft Academic Search

    B. M. Liaw; Y. X. Liu; E. A. Villars

    Impact-induced damage mechanisms in Glare and ARALL fiber-metal laminates subject to instrumented drop-weight impacts at various impact energies and temperatures were studied. Damage in pure aluminum panels impacted by foreign objects was mainly characterized by large plastic deformation surrounding a deep penetration dent. On the other hand, plastic deformation in fiber-metal laminates was often not as severe although the penetration

  20. Stiffness Properties Of Laminated Graphite/Epoxy Cylinders

    NASA Technical Reports Server (NTRS)

    Tolbert, R. Noel

    1988-01-01

    Report discusses stiffnesses of cylindrical shells formed from composite graphite/epoxy laminates, as calculated from traditional composite-lamination theory. Shells evaluated for use as cases for solid-fuel rocket motors. Stiffness results compared with quasi-experimental stiffnesses developed from pressure tests of cylindrical bottles. Sensitivities of stiffnesses to variations in constituent materials and in geometric parameters examined with help of two computer programs, included in appendix to report.

  1. Laminate composites with enhanced pyroelectric effects for energy harvesting

    Microsoft Academic Search

    H. H. S. Chang; Z. Huang

    2010-01-01

    A pyroelectric coefficient enhanced 2-2 connectivity laminate composites' energy harvesting credentials have been assessed. The use of the electrothermal coupling factor for laminate composites (kLam2) for such an assessment has been appraised while the experimental samples are evaluated to show a significant improvement in their performance via pyroelectric coefficient enhancement, demonstrative of their great potential in energy harvesting applications. A

  2. Fracture analysis of local delaminations in laminated composites

    NASA Technical Reports Server (NTRS)

    Sriram, P.; Armanios, Erian A.

    1988-01-01

    A shear deformation model was developed to analyze local delaminations growing from transverse cracks in 90 degree plies located around the mid plane of symmetric laminates. The predictions of the model agree reasonably with experimental data from T300/934 graphite epoxy laminates. The predicted behavior is such that, in combination with an edge delamination model, the critical loads can be predicted accurately in the range of n from .5 to 8.

  3. 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.

  4. 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

  5. Tracer Lamination in the Stratosphere: A Global Climatology

    NASA Technical Reports Server (NTRS)

    Appenzeller, Christof; Holton, James R.

    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 and on ozone-like pseudotracer data is presented. Three stratospheric regions with high lamination rates were found: the part of the stratospheric overworld which is influenced by the polar vortex, the part of the lowermost stratosphere which is influenced by the tropopause and a third region in the subtropical lower stratosphere mainly characterized with strong vertical shear. High lamination rates in the stratospheric overworld were absent during summer, whereas in the lowermost stratosphere high lamination rates were found year-round. This is consistent with the occurrence and seasonal variation of the horizontal tracer gradient and vertical shear necessary for tilting the tracer surfaces. During winter, high lamination rates associated with the stratospheric polar vortex are present down to approximately 100 hPa. Several features of the derived climatology are roughly consistent with earlier balloon-borne studies. The patterns in the southern and northern hemisphere are comparable, but details differ as anticipated from a less disturbed and more symmetric southern polar vortex.

  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. 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.

  8. Role of lamin b1 in chromatin instability.

    PubMed

    Butin-Israeli, Veronika; Adam, Stephen A; Jain, Nikhil; Otte, Gabriel L; Neems, Daniel; Wiesmüller, Lisa; Berger, Shelly L; Goldman, Robert D

    2015-03-01

    Nuclear lamins play important roles in the organization and structure of the nucleus; however, the specific mechanisms linking lamin structure to nuclear functions are poorly defined. We demonstrate that reducing nuclear lamin B1 expression by short hairpin RNA-mediated silencing in cancer cell lines to approximately 50% of normal levels causes a delay in the cell cycle and accumulation of cells in early S phase. The S phase delay appears to be due to the stalling and collapse of replication forks. The double-strand DNA breaks resulting from replication fork collapse were inefficiently repaired, causing persistent DNA damage signaling and the assembly of extensive repair foci on chromatin. The expression of multiple factors involved in DNA replication and repair by both nonhomologous end joining and homologous repair is misregulated when lamin B1 levels are reduced. We further demonstrate that lamin B1 interacts directly with the promoters of some genes associated with DNA damage response and repair, including BRCA1 and RAD51. Taken together, the results suggest that the maintenance of lamin B1 levels is required for DNA replication and repair through regulation of the expression of key factors involved in these essential nuclear functions. PMID:25535332

  9. Cell nuclei spin in the absence of lamin b1.

    PubMed

    Ji, Julie Y; Lee, Richard T; Vergnes, Laurent; Fong, Loren G; Stewart, Colin L; Reue, Karen; Young, Stephen G; Zhang, Qiuping; Shanahan, Catherine M; Lammerding, Jan

    2007-07-01

    Mutations of the nuclear lamins cause a wide range of human diseases, including Emery-Dreifuss muscular dystrophy and Hutchinson-Gilford progeria syndrome. Defects in A-type lamins reduce nuclear structural integrity and affect transcriptional regulation, but few data exist on the biological role of B-type lamins. To assess the functional importance of lamin B1, we examined nuclear dynamics in fibroblasts from Lmnb1(Delta/Delta) and wild-type littermate embryos by time-lapse videomicroscopy. Here, we report that Lmnb1(Delta/Delta) cells displayed striking nuclear rotation, with approximately 90% of Lmnb1(Delta/Delta) nuclei rotating at least 90 degrees during an 8-h period. The rotation involved the nuclear interior as well as the nuclear envelope. The rotation of nuclei required an intact cytoskeletal network and was eliminated by expressing lamin B1 in cells. Nuclear rotation could also be abolished by expressing larger nesprin isoforms with long spectrin repeats. These findings demonstrate that lamin B1 serves a fundamental role within the nuclear envelope: anchoring the nucleus to the cytoskeleton. PMID:17488709

  10. Response of automated tow placed laminates to stress concentrations

    NASA Technical Reports Server (NTRS)

    Cairns, Douglas S.; Ilcewicz, Larry B.; Walker, Tom

    1993-01-01

    In this study, the response of laminates with stress concentrations is explored. Automated Tow Placed (ATP, also known as Fiber Placement) laminates are compared to conventional tape layup manufacturing. Previous tensile fracture tests on fiber placed laminates show an improvement in tensile fracture of large notches over 20 percent compared to tape layup laminates. A hierarchial modeling scheme is presented. In this scheme, a global model is developed for laminates with notches. A local model is developed to study the influence of inhomogeneities at the notch tip, which are a consequence of the fiber placement manufacturing technique. In addition, a stacked membrane model was developed to study delaminations and splitting on a ply-by-ply basis. The results indicate that some benefit with respect to tensile fracture (up to 11 percent) can be gained from inhomogeneity alone, but that the most improvement may be obtained with splitting and delaminations which are more severe in the case of fiber placement compared to tape layup. Improvements up to 36 percent were found from the model for fiber placed laminates with damage at the notch tip compared to conventional tape layup.

  11. Interface fracture and composite deformation of model laminates

    NASA Astrophysics Data System (ADS)

    Fox, Matthew R.

    Model laminates were studied to improve the understanding of composite mechanical behavior. NiAl/Mo and NiAl/Cr model laminates, with a series of interfaces, were bonded at 1100°C. Reaction layers were present in all laminates, varying in thickness with bonding conditions. Interface fracture strengths and resistances were determined under primarily mode II loading conditions using a novel technique, the asymmetrically-loaded shear (ALS) test, in which one layer of the laminate was loaded in compression, producing a stable interface crack. The NiAl/Mo interface was also fractured in four-point bending. A small amount of plasticity was found to play a role in crack initiation. During steady-state mode II interface fracture of NiAl/Mo model laminates, large-scale slip was observed near the crack tip in the NiAl adjacent to the interface. After testing, the local slope and curvature of the interface were characterized at intervals along the interface and at slip locations to qualitatively describe local stresses present at and just ahead of the crack tip. The greatest percentage of slip occurred where closing forces on the crack tip were below the maximum value and were decreasing with crack growth. A mechanism for crack propagation is presented describing the role of large-scale slip in crack propagation. The mechanical response of structural laminates in 3-D stress states, as would be present in a polycrystalline aggregate composed of lamellar grains, are lacking. In order to understand the response of laminates composed of hard and soft phases, Pb/Zn laminates were prepared and tested in compression with varying lamellar orientation relative to the loading axis. A model describing the mechanical response in a general state assuming elastic-perfectly plastic isotropic layers was developed. For the 90° laminate, a different approach was applied, using the friction hill concepts used in forging analyses. With increasing ratios of cross-sectional radius to layer thickness for each layer, the model predicts the laminate yield strength, increasing up to the rule of mixtures yield strength.

  12. Testing and simulation of composite laminates under impact loading

    NASA Astrophysics Data System (ADS)

    Dang, Xinglai

    Owing to their high stiffness-to-weight and high strength-to-weight ratios, fiber-reinforced polymer-matrix composite laminates are excellent materials for high-performance structures. However, their properties in the thickness direction are very poor as they are weakly bonded by polymeric matrices through laminate interfaces. Accordingly, when a composite laminate is subjected to impact loading, high interlaminar stresses along with the low interlaminar strengths could easily result in interlaminar damage such as delamination. This thesis investigated the response of composite laminates under low-velocity impact and presented numerical techniques for impact simulation. To begin with, instrumented drop-weight impacts ranging from subperforation to perforation levels were introduced to composite laminates having various dimensions and thicknesses. Damaged composite laminates were then subjected to compression-after-impact tests for evaluations of residual properties. Experimental results revealed that perforation was an important damage milestone since impact parameters such as peak force, contact duration, maximum deflection and energy absorption, and residual properties such as compressive stiffness, strength and energy absorption all reached critical levels as perforation took place. It was also found that thickness played a more important role than in-plane dimensions in perforation process. In order to understand more about the relationship between laminate thickness and perforation resistance and to present an economical method to improve perforation resistance, thick laminated composite plates and their assembled counterparts were investigated and compared. An energy profile correlating the impact energy and absorbed energy at all energy levels for each type of composite plates investigated was established and found to be able to address the relationship between energy and damage. Experimental results concluded that increasing thickness was more efficient than improving assembling stiffness in raising perforation resistance. As a first step to simulate composite response to impact loading, LS-DYNA3D was used for numerical analysis. However, due to its inability to describe interlaminar stresses, no delamination simulation could be achieved. As delamination played a very important role in damage process, a computational scheme capable of identifying interlaminar stresses and considering both numerical accuracy and computational efficiency was required for impact simulation. Accounting for interlaminar shear stress continuity and having degrees of freedom independent of layer number, a laminate theory named Generalized Zigzag Theory was formulated into a finite element subroutine and integrated into ABAQUS code. The computational scheme was able to present reasonable interlaminar shear stresses via an updated Lagragian algorithm. Combining the calculated interlaminar stresses with a delamination failure criterion, the computer program was able to predict the response of composite laminates up to the onset of delamination. Further computational simulation involving all damage modes should be considered in future studies.

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...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...

  15. 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...

  16. 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...

  17. Diatom productivity in the eastern Gulf of Guinea during the last 20,000 years

    NASA Astrophysics Data System (ADS)

    Crosta, Xavier; Schneider, Ralph; Weldeab, Syee; Müller, Peter

    2010-05-01

    Biogenic silica and diatom accumulation rates are used to document siliceous productivity in the Gulf of Guinea in relation to oceanographic and climatic changes. Diatom assemblages were identified in core GeoB4905-4, retrieved off the Sanaga River, to congruently track oceanographic changes in the eastern Gulf of Guinea, precipitation and wind regime changes in equatorial Africa. Diatom productivity was greatest during the 12000-11000 and 9000-6000 calendar years BP periods (cal yr BP) when sea-surface temperature were warmer (Weldeab et al., 2007). At the assemblage level, greater diatom productivity periods demonstrated higher relative abundances of sub-tropical and freshwater diatoms and lower relative abundances of meroplanktonic diatoms and brackish water diatoms. Windblown diatoms were also absent during these periods. Diatom productivity was lowest during the 20000-12000 and 5000-0 cal yr BP periods when relative abundances of sub-tropical and freshwater diatoms decreased and abundances of meroplanktonic and brackish water diatoms increased. Windblown diatoms appeared solely during these periods. These results indicate that diatom productivity and oceanography in the eastern part of the Gulf of Guinea (governed by the Guinea Current in surface and the Equatorial Under-Current in sub-surface) are decoupled. Similarly, the wind regime can not explain the Holocene pattern of diatom productivity recorded here. Siliceous productivity is rather controlled by riverine input by the Sanaga and Niger rivers and therefore precipitation over western/central equatorial Africa. More precisely, diatom accumulation rates and assemblages argue for enhanced precipitation during the Early and Mid-Holocene periods and drier conditions during the last glacial, the Younger Dryas and the Late Holocene in agreement with studies of lake levels in eastern equatorial Africa (Gasse, 2000; Gasse et al., 2009) and geochemical data from the Gulf of Guinea (Schefuss et al., 2005; Weldeab et al., 2005; Weijers et al., 2009). Late glacial and Holocene changes in precipitation and wind activity may result from the combined influence of the Asian monsoon and the Inter-Tropical Convergence Zone (ITCZ) latitudinal migration. Gasse, 2000, Quaternary Science Reviews 19, 189-211. Gasse et al., 2009, Quaternary Science Reviews 27, 2316-2340. Schefuss et al., 2005, Nature 437, 1003-1006. Weldeab et al., 2005, Geology 33(12), doi: 10.1130/G21874. Weldeab et al., 2007, G-Cubed 8(5), Q05P22, doi:10.1029/2006GC001360. Weijers et al., 2009, Geochimica and Cosmochimica Acta 73, 119-132.

  18. Diatom species abundance and morphologically-based dissolution proxies in coastal Southern Ocean assemblages

    NASA Astrophysics Data System (ADS)

    Warnock, Jonathan P.; Scherer, Reed P.

    2015-07-01

    Taphonomic processes alter diatom assemblages in sediments, thus potentially negatively impacting paleoclimate records at various rates across space, time, and taxa. However, quantitative taphonomic data is rarely included in diatom-based paleoenvironmental reconstructions and no objective standard exists for comparing diatom dissolution in sediments recovered from marine depositional settings, including the Southern Ocean's opal belt. Furthermore, identifying changes to diatom dissolution through time can provide insight into the efficiency of both upper water column nutrient recycling and the biological pump. This is significant in that reactive metal proxies (e.g. Al, Ti) in the sediments only account for post-depositional dissolution, not the water column where the majority of dissolution occurs. In order to assess the range of variability of responses to dissolution in a typical Southern Ocean diatom community and provide a quantitative guideline for assessing taphonomic variability in diatoms recovered from core material, a sediment trap sample was subjected to controlled, serial dissolution. By evaluating dissolution-induced changes to diatom species' relative abundance, three preservational categories of diatoms have been identified: gracile, intermediate, and robust. The relative abundances of these categories can be used to establish a preservation grade for diatom assemblages. However, changes to the relative abundances of diatom species in sediment samples may reflect taphonomic or ecological factors. In order to address this complication, relative abundance changes have been tied to dissolution-induced morphological change to the areolae of Fragilariopsis curta, a significant sea-ice indicator in Southern Ocean sediments. This correlation allows differentiation between gracile species loss to dissolution versus ecological factors or sediment winnowing. These results mirror a similar morphological dissolution index from a parallel study utilizing Fragilariopsis kerguelensis, suggesting that results are applicable to a broad spectrum of diatoms typically preserved in the sediments.

  19. The epizoic diatom community on four bryozoan species from Helgoland (German Bight, North Sea)

    NASA Astrophysics Data System (ADS)

    Wuchter, Cornelia; Marquardt, Jürgen; 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.

  20. Settling fluxes of diatoms to the interior of the Antarctic circumpolar current along 170 °W

    NASA Astrophysics Data System (ADS)

    Grigorov, Ivo; Rigual-Hernandez, Andrés 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.

  1. Damage growth in composite laminates with interleaves

    NASA Technical Reports Server (NTRS)

    Goree, James G.

    1987-01-01

    The influence of placing interleaves between fiber reinforced plies in multilayered composite laminates is investigated. The geometry of the composite is idealized as two dimensional, isotropic, linearly elastic media made of a damaged layer bonded between two half planes and separated by thin interleaves of low extensional and shear moduli. The damage in the layer is taken in the form of a symmetric crack perpendicular to the interface and may extend up to the interface. The case of an H-shaped crack in the form of a broken layer with delamination along the interface is also analyzed. The interleaves are modeled as distributed shear and tension springs. Fourier integral transform techniques are used to develop solutions in terms of singular integral equations. An asymptotic analysis of the integral equations based on Muskhelishvili's techniques reveals logarithmically singular axial stresses in the half plane at the crack tips for the broken layer. For the H shaped crack, similar singularities are found to exist in the axial stresses at the interface crack tips in the layer and the half plane. The solution of the equations is found numerically for the stresses and displacements by using the Hadamard's concept of direct differentiation of Cauchy integrals as well as Gaussian integration techniques.

  2. Tape cast bioactive metal-ceramic laminates for structural application

    NASA Astrophysics Data System (ADS)

    Clupper, Daniel Christopher

    Bioglass 45S5, is a silica based glass which is able to rapidly form strong bonds with bone and soft tissue in vivo. It is used clinically to replace damaged ear ossicles and in dental surgery to help maintain the structural integrity of the jaw bone. The goal of the research was to demonstrate that Bioglass can be toughened by lamination with metallic layers while maintaining bioactivity. Improvement of the mechanical properties of Bioglass 45SS would allow for additional clinical applications, such as fracture fixation plates, or vertebral spacers. Bioglass 45S5 was tape cast and laminated with clinically relevant metals (316L, stainless steel and titanium) as well as copper in an effort to demonstrate that the effective toughness, or area under the load-deflection diagram can be increased significantly through ductile layer lamination. The average strength of monolithic tape cast sintered Bioglass was as high as 150 MPa and the toughness measured approximately 1.0 MPa m1/2. Copper-Bioglass laminates clearly demonstrated the toughening effect of metal layers on tape cast sintered Bioglass 45S5. Steel-Bioglass laminates, although less tough than the copper-Bioglass laminates, showed higher strengths. In vitro bioactivity tests of both titanium and steel Bioglass laminates showed the formation of mature and thick hydroxyapatite layers after 24 hours in Tris buffer solution. Under the standard test conditions, the bioactivity of monolithic tape cast sintered Bioglass increased with increasing sintering temperature. For samples sintered at 1000°C, thick crystalline layers of hydroxyapatite formed within 24 hours in Tris buffer solution. The bioactivity of these samples approached that of amorphous bulk Bioglass. Samples processed at 800°C were able to form thick crystalline hydroxyapatite layer after 24 hours when the test solution volume was increased by eight times.

  3. Muscle dystrophy-causing ?K32 lamin A/C mutant does not impair functions of nucleoplasmic LAP2? - lamin A/C complexes in mice

    PubMed Central

    Pilat, Ursula; Dechat, Thomas; Bertrand, Anne T; Woisetschläger, Nikola; Gotic, Ivana; Spilka, Rita; Biadasiewicz, Katarzyna; Bonne, Gisèle; Foisner, Roland

    2015-01-01

    Summary A-type lamins are components of the nuclear lamina, a filamentous network of the nuclear envelope in metazoans that supports nuclear architecture. In addition, lamin A/C can also be found in the nuclear interior. This nucleoplasmic lamin pool is soluble in physiological buffer, depends on the presence of the lamin-binding protein, Lamina-associated polypeptide 2? (LAP2?) and regulates cell cycle progression in tissue progenitor cells. ?K32 mutations in A-type lamins cause severe congenital muscle disease in humans and a muscle maturation defect in Lmna?K32/?K32 knock-in mice. At molecular level, mutant ?K32 lamin A/C protein levels were reduced and all mutant lamin A/C was soluble and mislocalized to the nucleoplasm. To test the role of LAP2? in nucleoplasmic ?K32 lamin A/C regulation and functions, we deleted LAP2? in Lmna?K32/?K32 knock-in mice. In double mutant mice the Lmna?K32/?K32- linked muscle defect was unaffected. LAP2? interacted with mutant lamin A/C, but unlike wild-type lamin A/C, the intranuclear localization of ?K32 lamin A/C was not affected by loss of LAP2?. In contrast, loss of LAP2? in Lmna?K32/?K32 mice impaired the regulation of tissue progenitor cells like in lamin A/C wild type animals. These data indicate that a LAP2?-independent assembly defect of ?K32 lamin A/C is predominant for the mouse pathology, while the LAP2?-linked functions of nucleoplasmic lamin A/C in the regulation of tissue progenitor cells are not affected in Lmna?K32/?K32 mice. PMID:23444379

  4. 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.

  5. 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 â20% 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

  6. BRASSIEREA VIVENS GEN. ET SP. NOV., A NEW BENTHIC MARINE DIATOM FROM THE BAHAMAS

    Microsoft Academic Search

    Michael K. Hein; Barbara M. Winsborough

    1999-01-01

    A new marine diatom genus and species, Brassierea vivens Hein & Winsborough, is described from linear stromatolites in the Exuma Islands, Bahamas. This small araphid diatom is bilaterally asymmetrical with a biarcuate dorsal margin and straight to slightly concave ventral margin. The axial area is eccentric and half-lanceolate in shape. The areolae are arranged in transapical striae that are separated

  7. Cadmium sensitivity, uptake, subcellular distribution and thiol induction in a marine diatom: Recovery from cadmium exposure

    Microsoft Academic Search

    Meng-Jiao Wang; Wen-Xiong Wang

    2011-01-01

    Studies in the recovery from metal stress and the tolerance development to metal exposure of aquatic organisms are important for the understanding of epidemic pollution. In this study, the responses of a marine diatom, Thalassiosira nordenskioeldii, following recovery from environmental cadmium (Cd) stress were investigated. The diatoms were exposed to different concentrations of Cd for 7 days, and were then

  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. Calibration of diatoms along a nutrient gradient in Florida Everglades Water Conservation Area2A, USA

    Microsoft Academic Search

    Sherri R. Cooper; Jacqueline Huvane; Panchabi Vaithiyanathan; Curtis J. Richardson

    1999-01-01

    The relationship between diatom taxa preserved in surface soils and environmental variables at 31 sites in Water Conservation Area 2A (WCA-2A) of the Florida Everglades was explored using multivariate analyses. Surface soils were collected along a phosphorus (P) gradient and analyzed for diatoms, total P, % nitrogen (N), %carbon (C), calcium (Ca), and biogenic silica (BSi). Phosphorus varied from 315-1781

  10. Release of dissolved organic matter by coastal diatoms Michael S. Wetz1 and Patricia A. Wheeler

    E-print Network

    Pierce, Stephen

    , their fate has important implications for global carbon (C) and nitrogen (N) cycles. For instance, diatoms of five coastal diatom species. For Chaetoceros decipiens, dissolved organic carbon (DOC) accumulated. This coincided with continued particulate organic carbon (POC) production and a threefold increase in the per

  11. CORRELATED EVOLUTION OF GENOME SIZE AND CELL VOLUME IN DIATOMS (BACILLARIOPHYCEAE)1

    E-print Network

    Moline, Mark

    . Diatom cell volume is an important component of the global carbon cycle; therefore, understanding of their frustules marks them as major players in the global biogeochemical silica cycle (Treguer et al. 1995, Yool to the cell (Cavalier-Smith 1978). The existence of this relation- ship in diatoms is of particular interest

  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. Spatio-temporal structure of diatom assemblages in a temperate estuary. A STATICO analysis

    Microsoft Academic Search

    Susana Mendes; Ma José Fernández-Gómez; Paula Resende; Mário Jorge Pereira; Ma Purificación Galindo-Villardón; Ulisses Miranda Azeiteiro

    2009-01-01

    This study examines the spatio-temporal structure of diatom assemblages in a temperate estuary (Ria de Aveiro, Western Portugal). Eighteen monthly surveys were conducted, from January 2002 to June 2003, at three sampling sites (at both high and low tide) along the estuarine salinity gradient. The relationship of diatom assemblages and environmental variables was analysed using the STATICO method, which has

  14. Diatom ecological preferences in a shallow temperate estuary (Ria de Aveiro, Western Portugal)

    Microsoft Academic Search

    Paula Resende; Ulisses Azeiteiro; Mário Jorge Pereira

    2005-01-01

    The study of the diatom ecological preferences was conducted from January 2002 to June 2003 in Canal de Mira, Ria de Aveiro, Western Portugal. Three sampling stations along a salinity gradient were sampled monthly, in new moon, at high and low tide. Salinity, temperature, pH, dissolved oxygen and nutrient contents were measured for each sampling station; chlorophyll a and diatom

  15. 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,

  16. 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

  17. 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

  18. 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.

  19. A biological function for cadmium in marine diatoms Todd W. Lane* and Francois M. M. Morel

    E-print Network

    Morel, François M. M.

    A biological function for cadmium in marine diatoms Todd W. Lane* and Franc¸ois M. M. Morel a biological function. Herein, we pro- vide evidence of a biological role for Cd in the marine diatom Thalassiosira weissflogii under conditions of low zinc, typical of the marine environment. Addition of Cd to Zn

  20. $\\Delta I=4$ and $\\Delta I=8$ bifurcations in rotational bands of diatomic molecules

    E-print Network

    Bonatsos, Dennis; Lalazissis, G A; Drenska, S B; Minkov, N; Raychev, P P; Roussev, R P; Bonatsos, Dennis

    1996-01-01

    It is shown that the recently observed $\\Delta I=4$ bifurcation seen in superdeformed nuclear bands is also occurring in rotational bands of diatomic molecules. In addition, signs of a $\\Delta I=8$ bifurcation, of the same order of magnitude as the $\\Delta I=4$ one, are observed both in superdeformed nuclear bands and rotational bands of diatomic molecules.

  1. Delta I = 2 staggering in rotational bands of diatomic molecules as a manifestation of interband interactions

    E-print Network

    Bonatsos, Dennis; Drenska, S B; Karoussos, N; Maruani, J; Minkov, N; Raychev, P P; Roussev, R P

    1999-01-01

    It is shown that the recently observed Delta I = 2 staggering seen in superdeformed nuclear bands is also occurring in certain electronically excited rotational bands of diatomic molecules. In the case of diatomic molecules the effect is attributed to interband interactions (bandcrossings).

  2. Delta I = 2 staggering in rotational bands of diatomic molecules as a manifestation of interband interactions

    E-print Network

    D. Bonatsos; C. Daskaloyannis; S. B. Drenska; N. Karoussos; J. Maruani; N. Minkov; P. P. Raychev; R. P. Roussev

    2001-06-01

    It is shown that the recently observed Delta I = 2 staggering seen in superdeformed nuclear bands is also occurring in certain electronically excited rotational bands of diatomic molecules. In the case of diatomic molecules the effect is attributed to interband interactions (bandcrossings).

  3. Do diatoms in the Swiss Alps reflect the length of ice-cover?

    Microsoft Academic Search

    André F. Lotter; Christian Bigler

    2000-01-01

    Diatom analyses in the water column, sediment traps, surficial sediments as well as in a short sedi- ment core from Hagelseewli (2339 m asl, Swiss Alps) give information about the present-day seasonal cycle of diatom blooms, taphonomic processes in the lake basin and the lake's history. Analyses of surficial sediments show that water depth and thus light and nutrient availability

  4. Semiclassical modeling of Rydberg wave-packet dynamics in diatomic molecules: Average decoupling theory

    E-print Network

    Cao, Jianshu

    Semiclassical modeling of Rydberg wave-packet dynamics in diatomic molecules: Average decoupling theory S. N. Altunata, J. Cao, and R. W. Field* Department of Chemistry, Massachusetts Institute 2002; published 10 May 2002 The semiclassical dynamics of Rydberg electronic wave packets in diatomic

  5. Sub-millimeter Spectroscopy of Diatomic Hydrides of Astrophysical Interest

    NASA Astrophysics Data System (ADS)

    Halfen, D. T.; Savage, C. S.; Apponi, A. J.; Ziurys, L. M.

    2005-05-01

    One class of interstellar molecules that are unique to the millimeter/far-infrared region of the electromagnetic spectrum are diatomic hydrides. These species have low moments of inertia, and therefore their rotational spectrum lies exclusively at sub-millimeter wavelengths and shorter. They are therefore extremely good targets for space-borne and airborne platforms such as Herschel, SOFIA, and SAFIR. Diatomic hydrides, both neutral (MH) and ionic (MH+) forms, are also basic building blocks of interstellar chemistry. In ionic form, they may be the "hidden" carriers of refractory elements in dense gas. To date, there is very little high resolution data available for many hydride species, in particular the ionic form. In the Ziurys laboratory, we have been conducting studies of metal hydrides using sub-millimeter direct absorption and velocity modulation techniques. We have measured the pure rotational spectrum of AlH (J = 0 -> 1), CrH (N = 0 -> 1), and SH+ (N = 0 -> 1). The hydride neutrals were created in a DC discharge of H2 and metal vapor, generated in a Broida-type oven. In the case of AlH (X1}? {+), the quadrupole hyperfine splitting in the J = 0 -> 1 transition was significantly revised from past measurements. The strongest five hyperfine transitions were recorded for CrH (X6}? {+) in its N = 0 -> 1 transition, the first direct observation of these lines. Spectra of AlD and CrD were measured as well. Finally, the N = 0 -> 1 transition of the SH+ ion (X3}? {-) has been recorded. For this molecule, an AC discharge of H2S and argon or CH3SH and argon was used for the synthesis, and velocity modulation methods were employed to isolate ion signals. Currently, velocity modulation techniques are being developed to study other diatomic hydride ions. Results of these investigations will be reported. This work is supported by NASA Grant NAG5-12719.

  6. Magneto-optical trapping of a diatomic molecule

    NASA Astrophysics Data System (ADS)

    Barry, J. F.; McCarron, D. J.; Norrgard, E. B.; Steinecker, M. H.; Demille, D.

    2014-08-01

    Laser cooling and trapping are central to modern atomic physics. The most used technique in cold-atom physics is the magneto-optical trap (MOT), which combines laser cooling with a restoring force from radiation pressure. For a variety of atomic species, MOTs can capture and cool large numbers of particles to ultracold temperatures (less than ~1 millikelvin) this has enabled advances in areas that range from optical clocks to the study of ultracold collisions, while also serving as the ubiquitous starting point for further cooling into the regime of quantum degeneracy. Magneto-optical trapping of molecules could provide a similarly powerful starting point for the study and manipulation of ultracold molecular gases. The additional degrees of freedom associated with the vibration and rotation of molecules, particularly their permanent electric dipole moments, allow a broad array of applications not possible with ultracold atoms. Spurred by these ideas, a variety of methods has been developed to create ultracold molecules. Temperatures below 1 microkelvin have been demonstrated for diatomic molecules assembled from pre-cooled alkali atoms, but for the wider range of species amenable to direct cooling and trapping, only recently have temperatures below 100 millikelvin been achieved. The complex internal structure of molecules complicates magneto-optical trapping. However, ideas and methods necessary for creating a molecular MOT have been developed recently. Here we demonstrate three-dimensional magneto-optical trapping of a diatomic molecule, strontium monofluoride (SrF), at a temperature of approximately 2.5 millikelvin, the lowest yet achieved by direct cooling of a molecule. This method is a straightforward extension of atomic techniques and is expected to be viable for a significant number of diatomic species. With further development, we anticipate that this technique may be employed in any number of existing and proposed molecular experiments, in applications ranging from precision measurement to quantum simulation and quantum information to ultracold chemistry.

  7. Distance Decay of Similarity in Neotropical Diatom Communities

    PubMed Central

    Wetzel, Carlos E.; Bicudo, Denise de C.; Ector, Luc; Lobo, Eduardo A.; Soininen, Janne; Landeiro, Victor L.; Bini, Luis M.

    2012-01-01

    Background The regression of similarity against distance unites several ecological phenomena, and thus provides a highly useful approach for illustrating the spatial turnover across sites. Our aim was to test whether the rates of decay in community similarity differ between diatom growth forms suggested to show different dispersal ability. We hypothesized that the diatom group with lower dispersal ability (i.e. periphyton) would show higher distance decay rates than a group with higher dispersal ability (i.e. plankton). Methods/Principal findings Periphyton and phytoplankton samples were gathered at sites distributed over an area of approximately 800 km length in the Negro River, Amazon basin, Brazil, South America (3°08?00?S; 59°54?30?W). Distance decay relationships were then estimated using distance-based regressions, and the coefficients of these regressions were compared among the groups with different dispersal abilities to assess our predictions. We found evidence that different tributaries and reaches of the Negro River harbor different diatom communities. As expected, the rates of distance decay in community similarity were higher for periphyton than for phytoplankton indicating the lower dispersal ability of periphytic taxa. Conclusions/Significance Our study demonstrates that the comparison of distance decay relationships among taxa with similar ecological requirements, but with different growth form and thus dispersal ability provides a sound approach to evaluate the effects of dispersal ability on beta diversity patterns. Our results are also in line with the growing body of evidence indicating that microorganisms exhibit biogeographic patterns. Finally, we underscore that clumbing all microbial taxa into one group may be a flawed approach to test whether microbes exhibit biogeographic patterns. PMID:23028767

  8. Littoral diatom assemblages as bioindicators of lake trophic status: A case study from perialpine lakes in Austria

    Microsoft Academic Search

    Aloisie Poulí?ková; Martin Duchoslav; Martin Dokulil

    2004-01-01

    Littoral diatom assemblages from different natural substrates (stones, mud, reeds) were used for estimating trophic status in seven perialpine lakes near Salzburg (Austria). Four trophic status indices were compared with the actual chemical data and the annual averages of total phosphorus concentrations. Diatom assemblages on different substrates indicated significantly different trophic status for the site. Indicators based on epiphytic diatoms

  9. Structure factors for tunneling ionization rates of diatomic molecules

    NASA Astrophysics Data System (ADS)

    Saito, Ryoichi; Tolstikhin, Oleg I.; Madsen, Lars Bojer; Morishita, Toru

    2015-05-01

    Within the leading-order, single-active-electron, and frozen-nuclei approximation of the weak-field asymptotic theory, the rate of tunneling ionization of a molecule in an external static uniform electric field is determined by the structure factor for the highest occupied molecular orbital. We present the results of systematic calculations of structure factors for 40 homonuclear and heteronuclear diatomic molecules by the Hartree-Fock method using a numerical grid-based approach implemented in the program X2DHF.

  10. Diatomic molecules in optical and microwave dipole traps

    SciTech Connect

    Lysebo, Marius [Faculty of Engineering, Oslo University College, NO-0130 Oslo (Norway); Veseth, Leif [Department of Physics, University of Oslo, NO-0316 Oslo (Norway)

    2011-03-15

    The dipole forces on rotating diatomic molecules are worked out in detail for optical as well as microwave radiation fields. The objective is in particular to investigate how the dipole forces and potentials depend on the subtle internal structure of the molecule, with special emphasis on hyperfine and Zeeman states. Dipole potentials are obtained from computations of the real part of the complex molecular polarizability, whereas the imaginary part yields the scattering force. Numerical examples are presented for {sup 23}Na{sub 2} and OH for optical (laser) fields related to strong electronic transitions and for microwave fields for the {Lambda} doubling in the OH ground state.

  11. On the Born-Oppenheimer approximation of diatomic molecular resonances

    E-print Network

    André Martinez; Vania Sordoni

    2015-06-25

    We give a new reduction of a general diatomic molecular Hamiltonian, without modifying it near the collision set of nuclei. The resulting effective Hamiltonian is the sum of a smooth semiclassical pseudodifferential operator (the semiclassical parameter being the inverse of the square-root of the nuclear mass), and a semibounded operator localised in the elliptic region corresponding to the nuclear collision set. We also study its behaviour on exponential weights, and give several applications where molecular resonances appear and can be well located.

  12. NIST-JANAF Thermochemical Tables. III. Diatomic Hydrogen Halide Gases

    NASA Astrophysics Data System (ADS)

    Shenyavskaya, Elena A.; Yungman, Vladimir S.

    2004-09-01

    The spectroscopic and thermodynamic properties of the four diatomic hydrogen halide molecules—HX(g), where X=F, Cl, Br, and I—have been reviewed. Four revised thermochemical tables result from this critical review. The revisions involved the consideration of new spectroscopic information and the use of a direct summation over states for the generation of the thermochemical tables. Compared to previous calculations, the entropies at 298.15 K are unchanged, but the high temperature values (T>4000 K) are significantly different.

  13. [Animal welfare in prevention and therapy of laminitis].

    PubMed

    Winkelsett, S; Vervuert, I

    2008-03-01

    Laminitis is a systemic disease which is manifested as a non infectious condition in the foot. The management of feeding and housing conditions is necessary to treat the endocrinological and metabolic disturbances of laminitic horses. The Equine Metabolic Syndrome (EMS) is predisposing for developing laminitis, and it is characterised by obesity, insulin resistance, hypertension and dyslipidaemia. A genetical predisposition is supposed and EMS is accompanied by a lack of exercise and inadequate energy intake. Laboratory examinations are of great importance for diagnosis. Analyses of insulin, glucose and ACTH are of interest. Several approaches to treat laminitis are available, including pharmacological and orthopaedic strategies as well as the management of the feeding and housing conditions. However, the prophylaxis to prevent laminitis has to be emphasised. Predisposed horses should be detected and adequately treated; especially weight reduction in obese horses is in the focus of interest. Horses in the acute stage of laminitis have to be stabled. Furthermore redistributing weight from the most stressed wall is necessary to prevent pain and to minimise laminar damage and displacement of the distal phalanx. In cases of displacement of the distal phalanx a close communication between the veterinarian and the authorised farrier is necessary, in these cases treatment should be supported by x-ray diagnosis. Horses have to be treated with NSAISs to ensure a proper therapy to consider animal welfare. Horses have to be fed with hay and supplemented with minerals and vitamins. Feeding exclusively straw and feed restriction has to be avoided. PMID:18444467

  14. 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.

  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 strength–ductility combination that is essential for metal forming applications. PMID:25685405

  16. Tension fatigue analysis and life prediction for composite laminates

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  17. Increasing ferromagnetic resonance frequency using lamination and shape

    NASA Astrophysics Data System (ADS)

    El-Ghazaly, A.; White, R. M.; Wang, S. X.

    2015-05-01

    The magnetic permeability frequency spectrum is one of the most critical properties for the operation of high frequency magnetic devices in the gigahertz regime. Permeability is fairly constant up to the ferromagnetic resonance (FMR) frequency, at which point the relative permeability drops to unity. Extending FMR to higher frequencies is thus imperative for developing GHz-range magnetic devices. The simulation and experimental investigations presented in this paper demonstrate how stacking layers to form a laminated film increases the FMR frequency by allowing flux closure between layers along the induced easy-axis direction. This flux closure reduces the demagnetization factor along the easy-axis direction by two orders of magnitude. This effect, however, is only observable in patterned films where the shape anisotropy is enough to result in variation of the FMR frequency. Experiments using patterned magnetic cores were performed to illustrate this effect. Through detailed investigation of the permeability spectra of both single layer and laminated CoTaZr magnetic films patterned into 500 ?m × L films (where L ranged from 200 ?m to 1000 ?m), the FMR frequency was extracted and proven to increase as a result of lamination. The degree to which the frequency is boosted by lamination increases exponentially as the length of the film is decreased. Through a combination of lamination and shape demagnetization, the effective anisotropy, which directly relates to FMR frequency, was shown to increase by about 100%.

  18. Biochemical and genetic engineering of diatoms for polyunsaturated fatty acid biosynthesis.

    PubMed

    Li, Hong-Ye; Lu, Yang; Zheng, Jian-Wei; Yang, Wei-Dong; Liu, Jie-Sheng

    2014-01-01

    The role of diatoms as a source of bioactive compounds has been recently explored. Diatom cells store a high amount of fatty acids, especially certain polyunsaturated fatty acids (PUFAs). However, many aspects of diatom metabolism and the production of PUFAs remain unclear. This review describes a number of technical strategies, such as modulation of environmental factors (temperature, light, chemical composition of culture medium) and culture methods, to influence the content of PUFAs in diatoms. Genetic engineering, a newly emerging field, also plays an important role in controlling the synthesis of fatty acids in marine microalgae. Several key points in the biosynthetic pathway of PUFAs in diatoms as well as recent progresses are also a critical part and are summarized here. PMID:24402175

  19. Biochemical and Genetic Engineering of Diatoms for Polyunsaturated Fatty Acid Biosynthesis

    PubMed Central

    Li, Hong-Ye; Lu, Yang; Zheng, Jian-Wei; Yang, Wei-Dong; Liu, Jie-Sheng

    2014-01-01

    The role of diatoms as a source of bioactive compounds has been recently explored. Diatom cells store a high amount of fatty acids, especially certain polyunsaturated fatty acids (PUFAs). However, many aspects of diatom metabolism and the production of PUFAs remain unclear. This review describes a number of technical strategies, such as modulation of environmental factors (temperature, light, chemical composition of culture medium) and culture methods, to influence the content of PUFAs in diatoms. Genetic engineering, a newly emerging field, also plays an important role in controlling the synthesis of fatty acids in marine microalgae. Several key points in the biosynthetic pathway of PUFAs in diatoms as well as recent progresses are also a critical part and are summarized here. PMID:24402175

  20. Preparation of biosilica structures from frustules of diatoms and their applications: current state and perspectives.

    PubMed

    Wang, Yu; Cai, Jun; Jiang, Yonggang; Jiang, Xinggang; Zhang, Deyuan

    2013-01-01

    Frustules, the silica shells of diatoms, have unique porous architectures with good mechanical strength. In recent years, biologists have learned more about the mechanism of biosilica shells formation; meanwhile, physicists have revealed their optical and microfluidic properties, and chemists have identified ways to modify them into various materials while maintaining their hierarchical structures. These efforts have provided more opportunities to use biosilica structures in microsystems and other commercial products. This review focuses on the preparation of biosilica structures and their applications, especially in the development of microdevices. We discuss existing methods of extracting biosilica from diatomite and diatoms, introduce methods of separating biosilica structures by shape and sizes, and summarize recent studies on diatom-based devices used for biosensing, drug delivery, and energy applications. In addition, we introduce some new findings on diatoms, such as the elastic deformable characteristics of biosilica structures, and offer perspectives on planting diatom biosilica in microsystems. PMID:23179621

  1. Fossil diatoms imply common cometary origin of space-dust and the Polonnaruwa meteorite

    NASA Astrophysics Data System (ADS)

    Miyake, N.; Wallis, M. K.; Wickramasinghe, N. C.

    2013-09-01

    IDPs collected in 2001 at 40km altitude by cryosamplers studied via scanning electron microscopy and EDX were found to contain siliceous fibres and whiskers, some isolated but often embedded in a mineral matrix. The newly-arrived Polonnaruwa meteorite gives strong evidence for the hypothesis that they are fragments of diatoms agglomerating on solar system icy bodies. Diatom frustules and even whole diatom skeletons are identifiable within the meteorite. Specimens of a siliceous exoskeleton with multiple spines/whiskers have also been found, thought to be freshwater diatoms. As diatoms are dependent on a source of nitrogenous organics, the siliceous whiskers within IDPs would be an indicator of a photosynthesizing ecosystem, probably on a comet.

  2. Quantitative and qualitative relationships between planktonic diatom communities and diatom assemblages in sedimenting material and surface sediments in Lake Baikal, Siberia

    Microsoft Academic Search

    David B. Ryves; David H. Jewson; Michael Sturm; Richard W. Battarbee; Roger J. Flower; Anson W. Mackay; Nikolai G. Granin

    2003-01-01

    Endemic planktonic diatoms are a major component of Lake Baikal sediments during interglacial periods. To investigate how these diatom assemblages are altered during sediment formation, quantitative plankton monitoring (1995-1998) was integrated with sediment trapping over 2 yr (1996-1997) in Baikal's southern basin (depth ;1,400 m). The traps consisted of both open (;6 monthly) and sequential (;2 weekly) collectors deployed throughout

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

    E-print Network

    Edel, Matthew Thomas

    1997-01-01

    monolithic glass. Some of the advantageous properties of laminated glass include a greater impact resistance, improved sound resistance, and better thermal insulation inside the structure. The most important advantage of laminated glass as compared...

  4. 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 ...

  5. 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...

  6. 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 ...

  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. 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...

  9. Surf zone diatoms: A review of the drivers, patterns and role in sandy beaches food chains

    NASA Astrophysics Data System (ADS)

    Odebrecht, Clarisse; Du Preez, Derek R.; Abreu, Paulo Cesar; Campbell, Eileen E.

    2014-10-01

    The accumulation of high biomass of diatoms in the surf zone is a characteristic feature of some sandy beaches where the wave energy is sufficiently high. A few species of diatoms, called surf diatoms, thrive in this harsh environment. The main processes driving the spatial and temporal distribution of surf diatoms as well as their standing biomass and growth were described twenty to thirty years ago based on studies conducted on the western coast of the United States of America and South African beaches. Since then, over fifty locations around the world have been reported to have surf diatom accumulations with most (three-quarters) of these being in the southern hemisphere. Their occurrence is controlled by physical and chemical factors, including wave energy, beach slope and length, water circulation patterns in the surf zone and the availability of nutrients to sustain the high biomass. The main forces driving the patterns of temporal variability of surf diatom accumulations are meteorological. In the short term (hours), the action of wind stress and wave energy controls the diatom accumulation. In the intermediate time scale (weeks to months), seasonal onshore winds of sufficient strength, as well as storm events are important. Furthermore, anthropogenic disturbances that influence the beach ecosystem as well as large-scale events, such as the El Niño Southern Oscillation, may lead to significant changes in surf diatom populations in the long term (inter-annual). Surf diatoms form the base of a short and very productive food chain in the inshore of the sandy beaches where they occur. However, the role of surf diatoms in the microbial food web is not clear and deserves further studies.

  10. Thin-walled orthotropic laminated beam theory

    NASA Astrophysics Data System (ADS)

    Pollock, Gerry Darren

    A refined beam theory is developed for thin-walled, orthotropic, laminated elastic beams. The motivation for the formulation is the necessity of accounting for deformations brought about by coupling induced shear strains in open section beams. The engineering formulation allows for completely arbitrary section geometry and lay-ups. The present theory and a related closed section theory are validated by comparisons with experimental, finite element, and other analytical methods. The results show the necessity of incorporating shear strain produced deformations for open sections. In general, both the open section and closed section results agree to within 10 to 15 percent of either experimental or finite element data for a broad range of section geometries, lay-ups and loadings. The present open and closed section formulations reduce, as required, to their classical isotropic counterparts when isotropic properties are invoked. Shear center concepts for anisotropic beams are investigated as well. For arbitrary ply lay-ups, it is impossible to find a point (shear center) at which applied shear loads simultaneously satisfy conditions of zero twist and zero resultant moment. The method of determining isotropic shear centers leads to moment balancing of resultant shear load and shear stresses about some point. A completely analogous procedure can be arrived at for anisotropic beams, and hence the condition of zero resultant torque is deemed the more natural condition to satisfy. The consequence is that the beam twists despite the fact that the shear load passes through the shear center. Anisotropic shear centers are found to be functions of material properties.

  11. The In Situ Ply Shear Strength Distributions in Graphite\\/Epoxy Laminated Composites

    Microsoft Academic Search

    Fu-Kuo Chang; Ming-Huei Chen

    1987-01-01

    An experimental and analytical investigation was performed to study the in situ ply shear strength in fiber-reinforced laminated composites. The effects of ply orientation and laminate thickness on the ply shear strength in laminates were the major concerns of the study. T300\\/1034-C Graphite\\/Epoxy cross-ply laminates were selected for the tests, and a rail shear fixture was used for measuring ply

  12. On the birefringent-coating method of stress analysis for fiber-reinforced laminated composites

    Microsoft Academic Search

    R. B. Pipes; J. W. Dalley

    1972-01-01

    A general relation based upon laminated-plate theory is developed which relates the state of stress throughout the thickness\\u000a of the fiber-reinforced composite laminate to experimentally determined surface strains. The usefulness of the developed relation\\u000a is discussed through an example given for a typical graphite-epoxy structural laminate. Birefringent coatings employed as\\u000a a method to determine laminate surface strains are investigated. Isochromatic

  13. An Historic Overview of the Development of Fibre Metal Laminates

    NASA Astrophysics Data System (ADS)

    Vermeeren, C. A. J. R.

    2003-07-01

    In this paper a brief overview of the history of Fibre Metal Laminates Arall and Glare is given as background information for the other, technical articles in this journal. The story of the development of Fibre Metal Laminates is rather a unique story in the history of aircraft materials: A university laboratory invented, developed and certified an aircraft material. Many parties were involved naturally, yet the very heart of the activity was the Structures and Materials Laboratory of the Faculty of Aerospace Engineering of Delft University of Technology in The Netherlands. At the break of the world's largest passenger transport aircraft, the Airbus A380, in which a substantial part of the fuselage will be made of Glare, the glass fibre-aluminium version of Fibre Metal Laminates, it is a good moment to tell some of its history.

  14. Fracture behavior of unidirectional boron/aluminum composite laminates

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    An experimental investigation of the fracture behavior of unidirectional boron/aluminum composite laminates was conducted in order to verify the results of mathematical models. These models predict the fiber stresses and displacements 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 agreed well with those predicted by the models. It was shown that for thin laminates the amount of damage and the fiber displacements do not depend strongly on the number of plies for a given notch width.

  15. Core preservation with a laminated, heat-sealed package

    SciTech Connect

    Hunt, P.K.; Cobb, S.L.

    1988-12-01

    A core preservation package was developed to maintain the reservoir characteristics of core samples and consequently to improve the quality of data obtained through laboratory core analyses. The package is a heat-sealable plastic-aluminum laminate similar to those common in the food-packaging industry. The laminated core preservation package acts as an impermeable barrier to water vapor and gases, and is resistant to chemical alteration and degradation by core fluids. These performance characteristics result in effective core preservation by maintaining the fluid content of the core. Other advantages of the laminated package are that it is fast and simple to use and eliminates the cumbersome dip-coat step used in some core preservation methods.

  16. 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.

  17. Compression and compression fatigue testing of composite laminates

    NASA Technical Reports Server (NTRS)

    Porter, T. R.

    1982-01-01

    The effects of moisture and temperature on the fatigue and fracture response of composite laminates under compression loads were investigated. The structural laminates studied were an intermediate stiffness graphite-epoxy composite (a typical angle ply laimna liminate had a typical fan blade laminate). Full and half penetration slits and impact delaminations were the defects examined. Results are presented which show the effects of moisture on the fracture and fatigue strength at room temperature, 394 K (250 F), and 422 K (300 F). Static tests results show the effects of defect size and type on the compression-fracture strength under moisture and thermal environments. The cyclic tests results compare the fatigue lives and residual compression strength under compression only and under tension-compression fatigue loading.

  18. 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.

  19. Laminated fabric as top electrode for organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Steim, R.; Chabrecek, P.; Sonderegger, U.; Kindle-Hasse, B.; Siefert, W.; Kroyer, T.; Reinecke, P.; Lanz, T.; Geiger, T.; Hany, R.; Nüesch, F.

    2015-05-01

    A simple lamination technique for conductive and semitransparent fabrics on top of organic photovoltaic cells is presented. Conductive fabrics consisted of metal wires woven in a fabric with polymeric fibers. The lamination of this conductive fabric with help of a high conductive poly(3,4-ethylenedioxythiophene) polystyrene sulfonate formulation results in well aligned low resistive metal wires as top electrode. Semitransparent flexible organic photovoltaic cells were processed with laminated fabrics as top electrode and sputtered layers of aluminum doped zinc oxide and Ag as bottom electrode. The organic photovoltaic cells showed similar performance when illuminated through the bottom or top electrode. Optical simulations were performed to investigate light scattering effects of the fabric. Results are very promising for photovoltaic and lightning devices as well as for all kinds of devices where semitransparent, highly conductive, and non-vacuum processed electrode materials are needed.

  20. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    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 (+/- 45 deg)s tensile test method and the (0/90 deg)s symmetric rail shear test method. It is shown that the first technique indicates the shear properties of the graphite/epoxy laminates investigated are fundamentally brittle in nature while the latter two methods tend to indicate that these laminates are fundamentally ductile in nature. Finally, predictions of incrementally determined tensile stress/strain curves utilizing the various different shear behaviour methods as input information are presented and discussed.

  2. Laminate composites with enhanced pyroelectric effects for energy harvesting

    NASA Astrophysics Data System (ADS)

    Chang, H. H. S.; Huang, Z.

    2010-06-01

    A pyroelectric coefficient enhanced 2-2 connectivity laminate composites' energy harvesting credentials have been assessed. The use of the electrothermal coupling factor for laminate composites (kLam2) for such an assessment has been appraised while the experimental samples are evaluated to show a significant improvement in their performance via pyroelectric coefficient enhancement, demonstrative of their great potential in energy harvesting applications. A lead zirconate titanate and stainless steel laminate composite with an 88% pyroelectric coefficient enhancement is shown to increase its maximum power density, efficiency, and electrothermal coupling factor by 254%, while other material pairings have also been evaluated to exhibit great promise in this application owing to a large pyroelectric coefficient enhancement accompanied by a reduction in total thermal mass.

  3. 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.

  4. 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.

  5. Minimality of invariant laminations for partially hyperbolic attractors

    NASA Astrophysics Data System (ADS)

    Nobili, Felipe

    2015-06-01

    Let f : M ? M be a C1-diffeomorphism over a compact boundaryless Riemannian manifold M, and ? a compact f-invariant subset of M admitting a partially hyperbolic spliting Tf? = Es ? Ec ? Eu over the tangent bundle Tf?. It's known from the Hirsch–Pugh–Shub theory that ? admits two invariant laminations associated to the extremal bundles Es and Eu. These laminations are families of dynamically defined immersed submanifolds of the M tangent, respectively, to the bundles Es and Eu at every point in ?. In this work, we prove that at least one of the invariant laminations of a transitive partially hyperbolic attractor with a one-dimensional center bundle is minimal: the orbit of every leaf intersects ? densely. This result extends those in Bonatti et al (2002 J. Inst. Math. Jussieu 1 513–41) and Hertz et al (2007 Fields Institute Communications vol 51 (Providence, RI: American Mathematical Society) pp 103–9) about minimal foliations for robustly transitive diffeomorphisms.

  6. Impact-induced fracture in a quasi-isotropic laminate

    NASA Technical Reports Server (NTRS)

    Joshi, S. P.; Sun, C. T.

    1987-01-01

    A systematic study of impact-induced fracture in a quasi-isotropic laminated composite is carried out. The main focus of the study is to understand damage initiation when a laminate is subjected to the impact of a foreign object. The total incipient damage of a laminate subjected to impact at higher than threshold velocity is also presented. The incipient damage is restricted to small growth from the initiation of the damage. The experimentally collected data are interpreted using a two-dimensional plane-strain finite-element analysis. The qualitative comparison suggests that the skew cracks in the proximal layers are primarily due to transverse shear stress. Skew cracks in the middle layers are also due to transverse shear stress. Vertical cracks in the distal layer are due to flexural stress transverse to the fiber orientation of the layer.

  7. Molecular Genetic Analysis of the Nested Drosophila melanogaster Lamin C Gene

    PubMed Central

    Schulze, Sandra R.; Curio-Penny, Beatrice; Li, Yuhong; Imani, Reza A.; Rydberg, Lena; Geyer, Pamela K.; Wallrath, Lori L.

    2005-01-01

    Lamins are intermediate filaments that line the inner surface of the nuclear envelope, providing structural support and making contacts with chromatin. There are two types of lamins, A- and B-types, which differ in structure and expression. Drosophila possesses both lamin types, encoded by the LamC (A-type) and lamin Dm0 (B-type) genes. LamC is nested within an intron of the essential gene ttv. We demonstrate that null mutations in LamC are lethal, and expression of a wild-type LamC transgene rescues lethality of LamC but not ttv mutants. Mutations in the human A-type lamin gene lead to diseases called laminopathies. To determine if Drosophila might serve as a useful model to study lamin biology and disease mechanisms, we generated transgenic flies expressing mutant LamC proteins modeled after human disease-causing lamins. These transgenic animals display a nuclear lamin aggregation phenotype remarkably similar to that observed when human mutant A-type lamins are expressed in mammalian cells. LamC aggregates also cause disorganization of lamin Dm0, indicating interdependence of both lamin types for proper lamina assembly. Taken together, these data provide the first detailed genetic analysis of the LamC gene and support using Drosophila as a model to study the role of lamins in disease. PMID:15965247

  8. 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.

  9. Metabolic Predispositions to Laminitis in Horses and Ponies: Obesity, Insulin Resistance and Metabolic Syndromes

    Microsoft Academic Search

    Raymond J. Geor

    2008-01-01

    Equine veterinarians have long recognized an association between metabolic abnormalities, notably obesity and insulin resistance (IR), and increased risk for laminitis in horses and ponies. Recent observational studies have provided evidence that an insulin-resistant phenotype is strongly linked with a predisposition to laminitis. Although descriptions of this laminitis-predisposed phenotype have varied, in general there is a clustering of obesity (generalized

  10. Interfacial stress analysis of geometrically modified adhesive joints in steel beams strengthened with FRP laminates

    Microsoft Academic Search

    Reza Haghani; Mohammad Al-Emrani; Robert Kliger

    2009-01-01

    One major problem when using bonded Fiber Reinforced Polymer laminates is the presence of high interfacial stresses near the end of the composite laminate which might govern the failure of the strengthening schedule. A method that has been proposed for reducing the magnitude of the interfacial stresses is laminate end tapering, which can be used with or without adhesive fillets.In

  11. Temperature dependence of the tensile behaviour of aramid\\/aluminium laminates

    Microsoft Academic Search

    H. F. Wu

    1993-01-01

    Aramid\\/aluminium laminates (ARALL® laminates) are a family of new hybrid composites made of alternating layers of thin aluminium alloy sheets with plies of epoxy adhesive prepreg containing unidirectional aramid fibres. The effect of elevated and cryogenic temperatures on these materials is critical to aerospace applications. ARALL 1, 2, 3, and 4 laminates have been tested in tension at temperatures ranging

  12. 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

  13. Mechanics and finite elements for the damped dynamic characteristics of curvilinear laminates and composite shell structures

    Microsoft Academic Search

    T. S. Plagianakos; D. A. Saravanos

    2003-01-01

    Integrated mechanics and a finite element method are presented for predicting the damping of doubly curved laminates and laminated shell composite structures. Damping mechanics are formulated in curvilinear co-ordinates from ply to structural level and the structural modal loss factors are calculated using the energy dissipation method. The modelling of damping at the laminate level is based on first order

  14. Mechanical behavior, damage tolerance and durability of fiber metal laminates for aircraft structures

    Microsoft Academic Search

    Guocai Wu

    2005-01-01

    This study systematically explores the mechanical behavior, damage tolerance and durability of fiber metal laminates, a promising candidate materials system for next generation aerospace structures. The experimental results indicated that GLARE laminates exhibited a bilinear deformation behavior under static in-plane loading. Both an analytical constitutive model based on a modified classical lamination theory which incorporates the elasto-plastic behavior of aluminum

  15. Author's personal copy Structure and stability of the lamin A tail domain and HGPS mutant

    E-print Network

    Buehler, Markus J.

    proteins (Wilson and Berk, 2010). A- type lamins, primarily lamin A and lamin C, are spliced from the LMNA) (Fong et al., 2006). This `survivability' may be a reason that the LMNA gene has more than 100 disease- causing mutations (Worman et al., 2010). Mutations in different regions of the LMNA gene lead

  16. Disruption of the lamin A and matrin-3 interaction by myopathic LMNA mutations.

    PubMed

    Depreux, Frederic F; Puckelwartz, Megan J; Augustynowicz, Aleksandra; Wolfgeher, Don; Labno, Christine M; Pierre-Louis, Dynora; Cicka, Danielle; Kron, Stephen J; Holaska, James; McNally, Elizabeth M

    2015-08-01

    The nuclear face of the nuclear membrane is enriched with the intermediate filament protein lamin A. Mutations in LMNA, the gene encoding lamin A, lead to a diverse set of inherited conditions including myopathies that affect both the heart and skeletal muscle. To gain insight about lamin A protein interactions, binding proteins associated with the tail of lamin A were characterized. Of 130 nuclear proteins found associated with the lamin A tail, 17 (13%) were previously described lamin A binding partners. One protein not previously linked to lamin A, matrin-3, was selected for further study, because like LMNA mutations, matrin-3 has also been implicated in inherited myopathy. Matrin-3 binds RNA and DNA and is a nucleoplasmic protein originally identified from the insoluble nuclear fraction, referred to as the nuclear matrix. Anti-matrin-3 antibodies were found to co-immunoprecipitate lamin A, and the lamin-A binding domain was mapped to the carboxy-terminal half of matrin-3. Three-dimensional mapping of the lamin A-matrin-3 interface showed that the LMNA truncating mutation ?303, which lacks the matrin-3 binding domain, was associated with an increased distance between lamin A and matrin-3. LMNA mutant cells are known to have altered biophysical properties and the matrin-3-lamin A interface is positioned to contribute to these defects. PMID:25948554

  17. 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.

  18. Spin-dependent mechanism for diatomic ligand binding to heme

    PubMed Central

    Franzen, Stefan

    2002-01-01

    The nature of diatomic ligand recombination in heme proteins is elucidated by using a Landau–Zener model for the electronic coupling in the recombination rate constant. The model is developed by means of explicit potential energy surfaces calculated by using density functional theory (DFT). The interaction of all possible spin states of the three common diatomic ligands, CO, NO, and O2, and high-spin heme iron is compared. The electronic coupling, rebinding barrier, and Landau–Zener force terms can be obtained and used to demonstrate significant differences among the ligands. In particular the intermediate spin states of NO (S = 3/2) and O2 (S = 1) are shown to be bound states. Rapid recombination occurs from these bound states in agreement with experimental data. The slower phases of O2 recombination can be explained by the presence of two higher spin states, S = 2 and S = 3, which have a small and relatively large barrier to ligand recombination, respectively. By contrast, the intermediate spin state for CO is not a bound state, and the only recombination pathway for CO involves direct recombination from the S = 2 state. This process is significantly slower according to the Landau–Zener model. Quantitative estimates of the parameters used in the rate constants provide a complete description that explains rebinding rates that range from femtoseconds to milliseconds at ambient temperature. PMID:12477933

  19. Temperature affects the silicate morphology in a diatom

    PubMed Central

    Javaheri, N.; Dries, R.; Burson, A.; Stal, L. J.; Sloot, P. M. A.; Kaandorp, J. A.

    2015-01-01

    Silica deposition by diatoms, a common component of the phytoplankton, has attracted considerable interest given the importance in ecology and materials science. There has recently been a great deal of research into the biological control of biosilicifcation, yet the in vivo physical and chemical effects have not been quantitatively investigated. We have grown the marine diatom Thalassiosira pseudonana in batch culture at three temperatures (14o, 18o, and 23?°C). We observed three distinct temperature-dependent growth phases. The morphology of silica was investigated using scanning electron microscopy followed by image analysis and supervised learning. The silica in the valves of the same species showed different structures: a mesh-like pattern in silicon-rich cultures and a tree-like pattern in silicon-limited cultures. Moreover, temperature affected this silica pattern, especially in silicon-limited cultures. We conclude that cells grown at 14?°C and 18?°C divide more successfully in Si-limited conditions by developing a tree-like pattern (lower silicification). PMID:26113515

  20. Calculations Of Diatomic Molecules With STO Basis Sets

    NASA Astrophysics Data System (ADS)

    Bouferguene, Ahmed; Etemadi, Babak; Jones, Herbert

    1997-04-01

    During the last decade, much progress is made in using Slater Type Orbitals(STOs) as atomic basis set in the quantum treatment of large systems. Indeed, according to early work on the Schrodinger equation, it was shown that STOs yield the best convergence of the variational wavefunctions, since they possess the proper behavior required by the solution of Schrodinger equation, namely, a cusp at the origin (T. Kato Commun. Pure and Appl. Math 10, 151 (1957)) and an exponential decrease at infinity. (S. Agmon, Lectures On Exponential Decay of Solutions of Second Order Elliptic Equations: Bound on Eigenfunctions of N-Body Schrodinger Operators, Princeton University, Princeton, NJ, 1982) However, due to the difficulties of setting up efficient algorithms for multicenter integrals, STOs were considered as sophisticated mathematical objects but of little practical interest. In this work, a general method allowing the calculation of multicenter integrals over STOs is presented. The method which is based on on an addition theorem for STOs and some of its mathematical and numerical properties will be presented. The numerical computations on diatomic molecules, H2 and N2 are carried out and compared with results obtained using Gaussian Type Orbitals (GTOs). Our numerical results for such small diatomics are of limited interest, but they are imporatant in fine tunning the computational machinery by comparing them with the data already available for such molecular systems. Furthermore, the conclusions drawn throughout this work will be used as guidlines in developing more general algorithms to treat complicated systems more efficiently.

  1. Temperature affects the silicate morphology in a diatom.

    PubMed

    Javaheri, N; Dries, R; Burson, A; Stal, L J; Sloot, P M A; Kaandorp, J A

    2015-01-01

    Silica deposition by diatoms, a common component of the phytoplankton, has attracted considerable interest given the importance in ecology and materials science. There has recently been a great deal of research into the biological control of biosilicifcation, yet the in vivo physical and chemical effects have not been quantitatively investigated. We have grown the marine diatom Thalassiosira pseudonana in batch culture at three temperatures (14(o), 18(o), and 23?(°)C). We observed three distinct temperature-dependent growth phases. The morphology of silica was investigated using scanning electron microscopy followed by image analysis and supervised learning. The silica in the valves of the same species showed different structures: a mesh-like pattern in silicon-rich cultures and a tree-like pattern in silicon-limited cultures. Moreover, temperature affected this silica pattern, especially in silicon-limited cultures. We conclude that cells grown at 14?(°)C and 18?(°)C divide more successfully in Si-limited conditions by developing a tree-like pattern (lower silicification). PMID:26113515

  2. When Lamins Go Bad: Nuclear Structure and Disease

    PubMed Central

    Schreiber, Katherine H.; Kennedy, Brian K.

    2013-01-01

    When mutations in nuclear lamins were first identified in skeletal and cardiac muscle diseases, the molecular events underlying pathogenesis were mere points of speculation. As more and more unrelated diseases were linked to lamins and other nuclear envelope proteins, nuclear structure and disease became an increasingly prominent research focus. Today, the disease mechanisms remain unresolved, but incredible progress has occurred. Nuclear envelope dysfunction is not only associated with altered nuclear activity, but also impaired structural dynamics and aberrant cell signaling. Building on these findings, small molecules are being discovered in animal models that may become effective therapeutic agents. PMID:23498943

  3. Delamination analysis of tapered laminated composites under tensile loading

    NASA Technical Reports Server (NTRS)

    Armanios, Erian A.; Parnas, Levend

    1991-01-01

    A study was conducted to analyze tapered composite laminates under tensile loading. A tapered construction made of S2/SP250 glass/epoxy laminate was used to achieve a thickness reduction using three consecutive dropped plies over a distance of 60 ply thicknesses. The principle of minimum complementary potential energy was used to determine interlaminar stresses. The interlaminar peel stress distribution shows a higher tensile intensity at the taper/thin portion juncture. The total strain energy release rate is determined using a simplified membrane model. Results are compared with a finite element simulation.

  4. Microwave detection of corrosion under paint and composite laminate coatings

    NASA Astrophysics Data System (ADS)

    Qaddoumi, Nasser; Zoughi, Reza

    1996-11-01

    Microwave and millimeter wave nondestructive methods using open-ended sensors have shown great potential for detecting minute thickness variations in laminate structures, in particular those backed by a conducting plate. Similarly, slight variations in the composition of dielectric materials may also be detected using a set of optimal parameters which include the standoff distance and the frequency of operation. In this paper the potential of using an open- ended rectangular waveguide for detecting the presence of rust under common paint and composite laminate coatings will be demonstrated. An experimental scanned image of a steel specimen with an area of induced corrosion will also be shown.

  5. Initial postbuckling response of anisotropic laminated rectangular plates

    NASA Technical Reports Server (NTRS)

    Johnson, Eric R.; Haftka, Raphael T.

    1992-01-01

    It has been shown that anisotropic plates can have unstable postbuckling behavior resulting in potential imperfection sensitivity. The present paper quantifies the degree of instability for rectangular, simply supported asymmetrically laminated plates. The analysis is based on asymptotic Koiter-type expansion of postbuckling response. The degree of postbuckling instability is quantified in terms of the reduction in load carrying capacity in the immediate postbuckling range. For graphite-epoxy plates it is found that this measure of instability is very small unless the lamination asymmetry is very pronounced.

  6. Autoantibodies to major and minor nuclear lamins are not restricted to autoimmune diseases.

    PubMed

    Senécal, J L; Raymond, Y

    1992-05-01

    Autoantibodies to lamins, the major polypeptide components of the nuclear lamina, have been reported in selected sera from patients with autoimmune diseases, including anti-lamin B in systemic lupus erythematosus (SLE) and anti-lamins AC in autoimmune chronic active hepatitis (CAH). We have studied the frequency, specificity, and isotypy of autoantibodies to major and minor lamins by immunoblotting on purified rat liver lamins in 190 sera from normal controls (n = 62), rheumatic disease controls (n = 42), and autoimmune disease patients (n = 86). The frequency of anti-lamin in normal controls was 85.5%, and ranged from 77 to 100% in the other groups. Anti-lamin frequency was not related to age, sex, or disease duration. Reactivity with lamin A or with minor lamins only was observed with 7 various sera and 2 normal sera, respectively. Between groups, the proportions of reactive sera were not different for lamins AC (18-47%) and for lamin B (22-36%). In particular, anti-lamin B and anti-lamins AC were not more common in SLE or CAH than in normal sera. The most frequent lamin specificity of SLE sera was anti-lamins ABC. Anti-lamin isotypes were IgG and/or IgM. Titers of IgM antibodies were not higher in any group. However, IgG anti-lamin titers were higher in CAH than in normal, ankylosing spondylitis, or SLE sera. The highest end point titers (greater than or equal to 1:3200) were observed with CAH, SLE, and rheumatoid arthritis (RA) sera with IgG anti-lamins AC, B, or ABC, or with IgM anti-lamins ABC. None of these SLE and RA patients had evidence of liver disease. Reactivity with minor lamins was more frequent in CAH. We conclude that anti-lamin autoantibodies are present in sera from most individuals and that the highest titers are found in sera from patients with autoimmune diseases. PMID:1611714

  7. Environmental Monitoring: Inferring the Diatom Index from Next-Generation Sequencing Data.

    PubMed

    Visco, Joana Amorim; Apothéloz-Perret-Gentil, Laure; Cordonier, Arielle; Esling, Philippe; Pillet, Loïc; Pawlowski, Jan

    2015-07-01

    Diatoms are widely used as bioindicators for the assessment of water quality in rivers and streams. Classically, the diatom biotic indices are based on the relative abundance of morphologically identified species weighted by their autoecological value. Obtaining such indices is time-consuming, costly, and requires excellent taxonomic expertise, which is not always available. Here we tested the possibility to overcome these limitations using a next-generation sequencing (NGS) approach to identify and quantify diatoms found in environmental DNA and RNA samples. We analyzed 27 river sites in the Geneva area (Switzerland), in order to compare the values of the Swiss Diatom Index (DI-CH) computed either by microscopic quantification of diatom species or directly from NGS data. Despite gaps in the reference database and variations in relative abundance of analyzed species, the diatom index shows a significant correlation between morphological and molecular data indicating similar biological quality status for the majority of sites. This proof-of-concept study demonstrates the potential of the NGS approach for identification and quantification of diatoms in environmental samples, opening new avenues toward the routine application of genetic tools for bioassessment and biomonitoring of aquatic ecosystems. PMID:26052741

  8. Distribution of diatoms and development of diatom-based models for inferring salinity and nutrient concentrations in the southern Baltic coastal lakes

    NASA Astrophysics Data System (ADS)

    Rzodkiewicz, Monika; Szpikowska, Gra?yna; Woszczyk, Micha?; Suchi?ska, Anita; Staszak-Piekarska, Agata; Piekarski, Pawe?; Burchardt, Lubomira; Messyasz, Beata

    2015-04-01

    The transfer function method has been developed as a useful tool for reconstruction of the past environmental changes. It is based on the assumption that the modern species, which ecological requirements are known, can be used to quantitative reconstructions of the past changes. The aim of the study was to gather test sets and to build diatom-based transfer function which can be used to reconstruct changes in the trophic state and salinity in the coastal lakes on the Polish Baltic coast. In the previous years there were several attempts made to reconstruct these parameters in lagoonal waters on the Baltic coasts in Germany, Denmark, Finland, Netherland, Sweden and Norway. But so far there is no diatom test set and transfer function built for the Polish coastal lakes. We sampled diatoms from 12 lakes located along the polish Baltic coast. At the same time we monitor the physical-chemical conditions in the lakes, which includes: lake water chemical composition (chlorides, phosphorous and sulphur), pH, salinity, conductivity, temperature, dissolved oxygen. We collected samples, few times per year (2012-2014) from the lakes as well as from the Baltic Sea and we analysed the whole phytoplankton composition. However the special focus in put on diatoms. In this poster we present new data from the Southern Baltic coastal lakes and quantify relationships between surface sediment diatom assemblages and present day environmental conditions. These relationships are then used to develop diatom-based transfer functions that will be applied to future studies of environmental change on the Polish Baltic coast. The results of the analysis show seasonal changes in the chemical and physical water properties. The diatom assemblage composition and species frequency also changed significantly. This study is a contribution to the projects: NN 306 064 640 financed by National Science Centre, Poland. The research was supported by Virtual Institute ICLEA (Integrated Climate and Landscape Evolution Analysis) funded by the Helmholtz Association.

  9. Decoupling of nutrient and grazer impacts on a benthic estuarine diatom assemblage

    NASA Astrophysics Data System (ADS)

    Armitage, Anna R.; Gonzalez, Vanessa L.; Fong, Peggy

    2009-09-01

    Strong interactions between top-down (consumptive) and bottom-up (resource supply) trophic factors occur in many aquatic communities, but these forces can act independently in some microphytobenthic communities. Within benthic estuarine diatom assemblages, the dynamics of these interactions and how they vary with abiotic environmental conditions are not well understood. We conducted a field experiment at two sites with varying habitat characteristics to investigate the interactive effects of grazers and nutrients on benthic estuarine diatoms. We crossed snail ( Cerithidea californica) and nutrient (nitrogen and phosphorus) addition treatments in enclosures on a restored tidal sandflat and a reference tidal mudflat in Mugu Lagoon, southern California. We repeated the study in summer 2000 and spring 2001 to assess temporal variation in the interactions. Snails caused a large decrease in diatom relative abundance and biomass (estimated as surface area); nutrients increased diatom abundance but did not alter diatom biomass. Snails and nutrients both reduced average diatom length, although the nutrient effect was weaker and temporally variable, occurring in the reference mudflat in the spring. There were few interactions between snail and nutrient addition treatments, suggesting that links between top-down and bottom-up forces on the diatom community were weak. There were no consistent differences in diatom assemblage characteristics between the two study sites, despite marked differences in sediment grain size and other abiotic characteristics between the sites. The strong diatom response to herbivores and weaker responses to enrichment differed from the previous studies where cyanobacteria increased in response to nutrient enrichment, further dissolving the "black box" perception of microphytobenthic communities.

  10. 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.

  11. 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.

  12. Analysis of local delaminations and their influence on composite laminate behavior

    NASA Technical Reports Server (NTRS)

    Obrien, T. K.

    1985-01-01

    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.

  13. 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.

  14. 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.

  15. Concurrent material-fabrication optimization of metal-matrix laminates under thermo-mechanical loading

    NASA Technical Reports Server (NTRS)

    Saravanos, D. A.; Morel, M. R.; Chamis, C. C.

    1991-01-01

    A methodology is developed to tailor fabrication and material parameters of metal-matrix laminates for maximum loading capacity under thermomechanical loads. The stresses during the thermomechanical response are minimized subject to failure constrains and bounds on the laminate properties. The thermomechanical response of the laminate is simulated using nonlinear composite mechanics. Evaluations of the method on a graphite/copper symmetric cross-ply laminate were performed. The cross-ply laminate required different optimum fabrication procedures than a unidirectional composite. Also, the consideration of the thermomechanical cycle had a significant effect on the predicted optimal process.

  16. Mechanics of damping for fiber composite laminates including hygro-thermal effects

    NASA Technical Reports Server (NTRS)

    Saravanos, D. A.; Chamis, Christos C.

    1989-01-01

    An integrated mechanics theory was developed for the modeling of composite damping from the micromechanics to the laminate level. Simplified, design oriented equations based on hysteretic damping are presented for on-axis plies, off-axis plies, and laminates including the effect of temperature, moisture, and interply hysteretic damping. The temperature rise within vibrating composite laminates resulting from strain energy dissipation is also modeled, and their coupled hygro-thermo-mechanical response is predicted. The method correlates well with reported damping measurements. Application examples illustrate the effect of various ply, laminate, and hygro-thermal parameters on the overall damping performance of composite laminates.

  17. Fracture and cyclic-fatigue behavior of ductile phase reinforced brittle matrix laminated composites: Effect of laminate orientation and reinforcement layer thickness

    Microsoft Academic Search

    Donald Ray Bloyer Jr.

    1997-01-01

    The fracture and cyclic fatigue properties of ductile phase reinforced brittle matrix laminated composites have been investigated through the examination of the effect of layer orientation and reinforcement layer thickness on niobium metal reinforced Nbsb3Al intermetallic laminates. Two laminate orientations, the crack arrester and crack divider, were prepared with layer thickness combinations of 50 mum Nb\\/200 mum Nbsb3Al, 125 mum

  18. Effect of eight benthic diatoms as feed on the growth of red abalone ( Haliotis rufescens ) postlarvae

    Microsoft Academic Search

    Juan Gabriel Correa-Reyes; María del Pilar Sánchez-Saavedra; María Teresa Viana; Norberto Flores-Acevedo; Carlos Vásquez-Peláez

    2009-01-01

    The growth rate of abalone post larvae of Haliotis rufescens fed ad libitum with a benthic monoalgal diatom culture maintained as monocultures on a semi-commercial scale, was evaluated\\u000a and correlated with the biochemical composition of the diatoms. The cell size (7.0?×?4.0 µm to 21.0?×?7.5 µm), protein percentage\\u000a (7.42% to 13.66%), and ash content (49.03% to 59.61%) were different among diatom strains; lipid

  19. Diatoms as a tracer of hydrological connectivity: the Oak Creek case study (Oregon, USA)

    NASA Astrophysics Data System (ADS)

    Antonelli, Marta; Martínez-Carreras, Nuria; Frentress, Jay; Pfister, Laurent

    2015-04-01

    The vast heterogeneity and complexity of rainfall-runoff transformation processes expresses itself in a multitude of water sources and flowpaths - ultimately resulting in the well-known intricacy of hydrological connectivity. Pioneering work of Pfister et al. (2009) conducted in the Weierbach catchment (0.45 km2, NW Luxembourg, semi-oceanic climate) demonstrated the potential for diatoms (unicellular, eukaryotic algae) to be used as a tracer of hydrological connectivity. Diatoms originating from terrestrial habitats had been shown to be systematically flushed from the riparian areas into the stream during storm events. Here, we present a study conducted in the Oak Creek(0.17 km2, Oregon, Mediterranean climate), characterised by a large riparian area. Our first working hypothesis (H1) stipulates that diatoms are an ubiquitous tracer of fast hydrological flowpaths. The second hypothesis (H2) states that the riparian area is the major reservoir of terrestrial diatoms that contributes to the flushing process during rainfall events. A winter rainfall-runoff event was monitored in March 2012. Diatom samples were collected from soil, moss, epipelon and streamwater in order to characterise the communities along the hillslope-riparian-stream (HRS) continuum. Diatoms in each sample were also assigned to different wetness categories (according to Van Dam et al., 1994). The catchment was instrumented with an ISCO automatic streamwater sampler and the samples were analysed for conductivity, 18O, 2H, chemical elements and presence/abundance of diatoms belonging to different wetness categories. Our results show that the percentage of diatom species originating from habitats located outside of the stream evolves along the rising and falling limbs of the hydrograph. This observation confirms the event-related flushing of diatoms from terrestrial habitats to the stream and, consequently, the potential for diatoms to be used for the detection of hydrological connectivity in the hillslope-riparian-stream continuum (H1). Moreover, almost no strictly terrestrial diatoms were found in the stream during the event, indicating the majority of the diatoms (identified as aerophytic) being exported from the riparian area (H2).

  20. Do diatoms percolate through soil and can they be used for tracing the origin of runoff?

    NASA Astrophysics Data System (ADS)

    De Graaf, Lenka; Cammeraat, Erik; Pfister, Laurent; Wetzel, Carlos; Klaus, Julian; Hissler, Christophe

    2015-04-01

    Tracers are widely used to study the movement of water in a catchment. Because of depletion of scientific possibilities with most common tracer types, we proposed the use of diatoms as a natural tracer. Paradoxical results on the contribution of surface runoff to the storm hydrograph were obtained in pioneer research on this idea. Diatom transport via the subsurface flow to the stream would explain this paradox. Prerequisite for this is vertical transport of diatoms through soils, which is the topic of this study. Emphasis is on percolation behavior (speed of percolation, speed of percolation over time, and species distribution) of Pseudostaurosira sp. and Melosira sp. (Bacillariophyceae) through undisturbed soil columns of contrasting substrates. Co-objective is to study the flowpaths of water through the soil columns. Natural undisturbed soil columns were sampled in the Attert basin (Luxembourg) on schist, marl and sandstone substrates. Rain simulation experiments were performed to study vertical diatom transport. Rhodamine dye experiments were carried out to gain insight in the active flowpaths of water, and breakthrough experiments were performed to study the responses of the soil columns to applied water. Diatoms were transported through the soil columns of the three substrates. A vast majority of diatom percolation took place within the first 15 minutes, percolation hereafter was marginal but nevertheless present. Peaks in diatom percolation corresponded with a high flux caused by the addition of the diatom culture, but seepage of diatoms along the sides is unlikely according to the species distribution and the rhodamine dye experiment. Pseudostaurosira sp. percolated significantly better than Melosira sp. Significantly more diatoms percolated through the marl columns compared to the schist columns and variance within the sandstone group was very high. Absolute differences between substrates however, were marginal. Most preferential flowpaths were observed in the marl columns, indicating highest active macroporosity in these columns. Although the sample size of this study was small, it is suspected that the highest diatom percolation percentages of the marl columns is linked to its greater macroporosity and most importantly, diatoms can percolate through soil (macro-) pores.

  1. Light-independent biosynthesis and assembly of the photosystem II complex in the diatom Chaetoceros gracilis.

    PubMed

    Nagao, Ryo; Tomo, Tatsuya; Narikawa, Rei; Enami, Isao; Ikeuchi, Masahiko

    2013-05-01

    Diatoms can survive for long periods in the dark. However, how biosynthesis of photosynthetic proteins contributes to survival in the dark is poorly understood. Using a radiolabeling technique, we examined whether de novo biosynthesis and assembly of photosynthetic proteins differs in light-adapted vs. dark-adapted marine diatoms (Chaetoceros gracilis). In light-adapted cells, D1 protein was heavily radiolabeled owing to rapid turnover of photosystem II (PSII). In dark-adapted cells (>24 h), the radiolabeling patterns of PSII components changed, but the PSII dimer still formed. Therefore, diatoms may regulate the biosynthesis of photosynthetic proteins for long-term survival in the dark. PMID:23499432

  2. The LMNA mutation p.Arg321Ter associated with dilated cardiomyopathy leads to reduced expression and a skewed ratio of lamin A and lamin C proteins

    SciTech Connect

    Al-Saaidi, Rasha [Research Unit for Molecular Medicine, Aarhus University and Aarhus University Hospital, Aarhus (Denmark); Rasmussen, Torsten B. [Department of Cardiology, Aarhus University Hospital, Aarhus (Denmark); Palmfeldt, Johan [Research Unit for Molecular Medicine, Aarhus University and Aarhus University Hospital, Aarhus (Denmark); Nissen, Peter H. [Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus (Denmark); Beqqali, Abdelaziz [Heart Failure Research Center, Academic Medical Center, Amsterdam (Netherlands); Hansen, Jakob [Department of Forensic Medicine, Bioanalytical Unit, University of Aarhus (Denmark); Pinto, Yigal M. [Heart Failure Research Center, Academic Medical Center, Amsterdam (Netherlands); Boesen, Thomas [Department of Molecular Biology and Genetics, University of Aarhus (Denmark); Mogensen, Jens [Department of Cardiology, Odense University Hospital, Odense (Denmark); Bross, Peter, E-mail: peter.bross@ki.au.dk [Research Unit for Molecular Medicine, Aarhus University and Aarhus University Hospital, Aarhus (Denmark)

    2013-11-15

    Dilated cardiomyopathy (DCM) is a disease of the heart muscle characterized by cardiac chamber enlargement and reduced systolic function of the left ventricle. Mutations in the LMNA gene represent the most frequent known genetic cause of DCM associated with disease of the conduction systems. The LMNA gene generates two major transcripts encoding the nuclear lamina major components lamin A and lamin C by alternative splicing. Both haploinsuffiency and dominant negative effects have been proposed as disease mechanism for premature termination codon (PTC) mutations in LMNA. These mechanisms however are still not clearly established. In this study, we used a representative LMNA nonsense mutation, p.Arg321Ter, to shed light on the molecular disease mechanisms. Cultured fibroblasts from three DCM patients carrying this mutation were analyzed. Quantitative reverse transcriptase PCR and sequencing of these PCR products indicated that transcripts from the mutant allele were degraded by the nonsense-mediated mRNA decay (NMD) mechanism. The fact that no truncated mutant protein was detectable in western blot (WB) analysis strengthens the notion that the mutant transcript is efficiently degraded. Furthermore, WB analysis showed that the expression of lamin C protein was reduced by the expected approximately 50%. Clearly decreased lamin A and lamin C levels were also observed by immunofluorescence microscopy analysis. However, results from both WB and nano-liquid chromatography/mass spectrometry demonstrated that the levels of lamin A protein were more reduced suggesting an effect on expression of lamin A from the wild type allele. PCR analysis of the ratio of lamin A to lamin C transcripts showed unchanged relative amounts of lamin A transcript suggesting that the effect on the wild type allele was operative at the protein level. Immunofluorescence microscopy analysis showed no abnormal nuclear morphology of patient fibroblast cells. Based on these data, we propose that heterozygosity for the nonsense mutation causes NMD degradation of the mutant transcripts blocking expression of the truncated mutant protein and an additional trans effect on lamin A protein levels expressed from the wild type allele. We discuss the possibility that skewing of the lamin A to lamin C ratio may contribute to ensuing processes that destabilize cardiomyocytes and trigger cardiomyopathy - Highlights: • We study disease mechanisms in DCM patients carrying PTC mutations in the LMNA gene. • The mutant transcript is degraded by the nonsense mediated mRNA decay system. • Skewed lamin A to lamin C protein ratio expressed from the wild type allele. • We suggest a combined pathomechanism: haploinsuffiency plus lamin A/C imbalance.

  3. Lamin B2 prevents chromosome instability by ensuring proper mitotic chromosome segregation

    PubMed Central

    Kuga, T; Nie, H; Kazami, T; Satoh, M; Matsushita, K; Nomura, F; Maeshima, K; Nakayama, Y; Tomonaga, T

    2014-01-01

    The majority of human cancer shows chromosomal instability (CIN). Although the precise mechanism remains largely uncertain, proper progression of mitosis is crucial. B-type lamins were suggested to be components of the spindle matrix of mitotic cells and to be involved in mitotic spindle assembly; thus, B-type lamins may contribute to the maintenance of chromosome integrity. Here, using a proteomic approach, we identified lamin B2 as a novel protein involved in CIN. Lamin B2 expression decreased in colorectal cancer cell lines exhibiting CIN, as compared with colorectal cancer cell lines exhibiting microsatellite instability (MIN), which is mutually exclusive to CIN. Importantly, lamin B2 knockdown in MIN-type colorectal cancer cells induced CIN phenotypes such as aneuploidy, chromosome mis-segregation and aberrant spindle assembly, whereas ectopic expression of lamin B2 in CIN-type colorectal cancer cells prevented their CIN phenotypes. Additionally, immunohistochemical analysis showed a lower expression of lamin B2 in cancer tissues extracted from patients with sporadic colorectal cancer (CIN-type) than that from patients with hereditary non-polyposis colorectal cancer (HNPCC; MIN type). Intriguingly, mitotic lamin B2 in MIN cancer cells was localized outside the spindle poles and mitotic lamin B2 localization was diminished in CIN cancer cells, suggesting an important role of lamin B2 in proper mitotic spindle formation. The obtained results suggest that lamin B2 maintains chromosome integrity by ensuring proper spindle assembly and that its downregulation causes CIN in colorectal cancer. PMID:24637494

  4. 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.

  5. 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.

  6. Equine laminitis: A journey to the dark side of venous

    Microsoft Academic Search

    Tom P. Robertson; Simon R. Bailey; John F. Peroni

    2009-01-01

    Equine laminitis is a crippling condition that continues to defy repeated efforts to delineate the precise mechanisms involved and develop effective therapeutic strategies for use in the clinic. In this article, the possible role of dysfunction of the laminar vasculature is discussed, with particular emphasis on the venous side of the laminar microvasculature and the possible role(s) that metabolic syndrome

  7. 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.

  8. Three-dimensional vibration analysis of rotating laminated composite blades

    SciTech Connect

    McGee, O.G. (Georgia Inst. of Tech., Atlanta, GA (United States). School of Civil Engineering); Chu, H.R. (Ohio State Univ., Columbus, OH (United States). Dept. of Civil Engineering)

    1994-07-01

    This work offers the first known three-dimensional continuum vibration analysis for rotating, laminated composite blades. A cornerstone of this work is that the dynamic energies of the rotating blade are derived from a three-dimensional elasticity based, truncated quadrangular pyramid model incorporating laminated orthotropicity, full geometric nonlinearity using an updated Lagrangian formulation and Coriolis acceleration terms. These analysis sophistications are included to accommodate the nonclassical directions of modern blade designs comprising thin, wide chord-lifting surfaces of laminated composite construction. The Ritz method is used to minimize the dynamic energies with displacements approximated by mathematically complete polynomials satisfying the vanishing displacement conditions at the blade root section exactly. Several tables and graphs are presented that describe numerical convergence studies showing the validity of the assumed displacement polynomials used herein. Nondimensional frequency data are presented for various rotating, truncated quadrangular pyramids, serving as first approximations of practical blades employed in aircraft engines and fans. A wide scope of results explain the influence of a number of parameters coined to rotating, laminated composite blade dynamics, namely aspect ratio (a/b), chord ratio (c/b), thickness ratio (b/h), variable thickness distribution (h[sub l]/h[sub t]), blade pretwist angle ([phi][sub 0]), composite fiber orientation angle ([theta]), and angular velocity ([Omega]). Additional examples are given that elucidate the significance of the linear and nonlinear kinematics used in the present three-dimensional formulation along with the importance of the Coriolis acceleration terms included in the analysis.

  9. Postbuckling and Mode Jumping Analysis of Composite Laminates Using an

    E-print Network

    Yu, Wenbin

    element analysis (FEA) shows a pretty good match in their numerical results in the primary post- bucklingPostbuckling and Mode Jumping Analysis of Composite Laminates Using an Asymptotically Correct, the analytic approach has the capability of explor- ing deeply into the post-secondary buckling realm

  10. Buckling analysis for anisotropic laminated plates under combined inplane loads

    NASA Technical Reports Server (NTRS)

    Viswanathan, A. V.; Tamekuni, M.; Baker, L. L.

    1974-01-01

    The buckling analysis presented considers rectangular flat or curved general laminates subjected to combined inplane normal and shear loads. Linear theory is used in the analysis. All prebuckling deformations and any initial imperfections are ignored. The analysis method can be readily extended to longitudinally stiffened structures subjected to combined inplane normal and shear loads.

  11. STEEL BEAMS STRENGTHENED WITH ULTRA HIGH MODULUS CFRP LAMINATES

    Microsoft Academic Search

    Nisal Abheetha Peiris

    2011-01-01

    Advanced composites have become one of the most popular methods of repairing and\\/or strengthening civil infrastructure in the past couple of decades. While the use of Fiber Reinforced Polymer laminates and sheets for the repair and strengthening of reinforced concrete structures is well established, research on the application of FRP composites to steel structures has been limited. The use of

  12. Monitoring of impact damages in composite laminates using wavelet transform

    Microsoft Academic Search

    Dae-Un Sung; Chun-Gon Kim; Chang-Sun Hong

    2002-01-01

    Low-velocity impact damage is a major concern in the design of structures made of advanced laminated composites, because such damage is mostly hidden inside and cannot be detected by visual inspection. It is found that the acoustic emission (AE) waves generated by impact loads are undistinguishable from each mode and amount of damage by the conventional analysis methods in time

  13. Numerical simulation of ballistic impact on composite laminates

    Microsoft Academic Search

    M. A. G. Silva; C. Cisma?iu; C. G. Chiorean

    2005-01-01

    The paper reports experimental and numerical simulation of ballistic impact problems on thin composite laminated plates reinforced with Kevlar 29. Ballistic impact was imparted with simulated fragments designed in accordance with STANAG-2920 on plates of different thickness. Numerical modelling was developed and used to obtain an estimate for the limit perforation velocity (V50) and simulate failure modes and damage. Computations

  14. Jump Systems and Laminated Manhattan Sets Jessica Cuomo

    E-print Network

    Ponomarenko, Vadim

    Jump Systems and Laminated Manhattan Sets Jessica Cuomo Department of Mathematical Sciences of lattice points satisfying a certain "two-step" axiom. A Manhattan set is the convex hull of a two-dimensional jump system. Taking multiple Manhattan sets, in layers, forms a three-dimensional object. We determine

  15. Photodegradation in ballistic laminates: Spectroscopy and lifetime extension

    SciTech Connect

    Renschler, C.L.; Stallard, B.R.; White, C.A.; Garcia, M.J.; Morse, H.E. [Sandia National Labs., Albuquerque, NM (United States). Properties of Organic Materials Dept.

    1996-06-01

    Several years ago, the Materials and Process Sciences Center (Org. 1800) was asked by Dept. 9613 to study the materials aging issues which had led to the loss of ballistic protection by Armored Tractor (AT) windshields and windows. The authors speculated that this loss of impact strength was due to photodegradation of the polycarbonate (PC) inboard ply. They developed a spectroscopic method to identify changes in the outboard surface of the PC, and showed that the changes in the surface which occurred upon natural aging in the field could be reproduced by exposing the laminates to a simulated solar flux. Based on these results, they recommended changes in the adhesive interlayers to filter out the ultraviolet (UV) light causing the aging problem. Working with the laminate vendor, PPG, they re-designed the laminates to implement these changes and block essentially all UV light from the inboard ply. The most recent phase of this work involved accelerated solar aging of laminates made with the new design to verify that photoaging effects have been blocked by the new materials. They report here the results of that study, and recommended follow-on work.

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

    E-print Network

    Jackson, Amy Lynn

    2013-04-10

    ??...?.???.....??????..10 Localization of Citrulline Production??????.???...?????....11 IgA and D-Lactate??.???????????...?????????.13 Approval????????????????.??...?????...??.14 III RESULTS ...???????..??????????????????15 Clinical Outcome... great that the coffin bone shifts downward (Figure 1.), (Pollitt, 2002). Treatments such as NSAID pain relievers and cryotherapy can prevent or lessen the degree of laminitis if begun in the developmental phase before symptoms occur (Van Epps, 2004...

  17. Magnetic properties of iron yoke laminations for SSC dipole magnets

    Microsoft Academic Search

    S. A. Kahn; G. H. Morgan

    1991-01-01

    The authors examine the magnetic properties for the iron used in the SSC (Superconducting Super Collider) yoke laminations so that the accelerator tolerance can be met. The accelerator requirements for field quality specify a tolerance on the variation in the central field. At machine injection the variation in field is attributed to coercivity, Hc. Requirements on the magnitude and the

  18. Opportunities for SUEX dry laminate resist in microfluidic MEMS applications

    E-print Network

    Opportunities for SUEX dry laminate resist in microfluidic MEMS applications Donald W Johnsona gradient through the film. With the added benefit of reduced baking times, and the use of polymer, the approach results in processing times of about 2 days for a 3-layer, all-polymer device. Furthermore, multi

  19. 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.

  20. Thermosonic gold wire bonding to palladium finishes on laminate substrates

    Microsoft Academic Search

    R. Wayne Johnson; Michael Palmer; Mike Bozack; Tamara Isaacs-Smith

    1998-01-01

    As the laminate substrate industry moves from hot air solder level (HASL) finishes, alternate plating finishes are being proposed, such as immersion gold\\/electroless nickel, electroless palladium and electroless silver. This paper presents results of an evaluation of the thermosonic gold ball wire bondability of electroless palladium. Two palladium thicknesses, with and without a nickel underlayer, from two vendors were evaluated.

  1. Fiber Metal Laminates — The Synthesis of Metals and Composites

    Microsoft Academic Search

    S. Krishnakumar

    1994-01-01

    Fiber Metal Laminates are a new class of advanced aerospace materials. They consist of thin metallic sheets bonded together with fiber reinforced adhesive matrices. Their most outstanding characteristic is exceptional fatigue resistance, which stems from the crack bridging effect of the fibers in the prepreg layers. Because of the many advantages they offer, such as higher strengths and lower densities

  2. FLEXURAL FIRST PLY FAILURE OF NOTCHED COMPOSITE LAMINATES

    E-print Network

    Collins, Gary S.

    FLEXURAL FIRST PLY FAILURE OF NOTCHED COMPOSITE LAMINATES B. Adeeko, L. Smith, A. Kothidar used more and more as a lightweight alternative to metals. Composites are materials made of two or more the first ply breaking point, or the maximum load the coupon could withstand before its outer fibers broke

  3. Modeling of ductile and brittle/brittle laminates

    SciTech Connect

    Chen, S.P.

    1996-02-01

    A micro-mechanical ``spring``-network model was used to simulate the deformation and fracture behaviors of ductile/brittle and brittle/brittle laminates. Effects of interfacial cohesion, moduli, grain boundary cohesion, yield stress are presented and compared with available experiments. We found that composites with higher yield stress and lower interfacial cohesion are tougher.

  4. Fatigue crack growth in fiber-metal laminates

    Microsoft Academic Search

    J. R. Yeh

    1995-01-01

    The fatigue behavior of cracked fiber-metal laminates containing residual stresses is studied. A finite element model employing special interface elements is developed for this study. The use of the interface element allows the simulation to be completed in a single finite element analysis conducted within the limitations of elasticity theory. The effect of crack closure at the crack tip in

  5. Modeling of fatigue crack growth in notched fiber metal laminates

    Microsoft Academic Search

    Po-Yu Chang; Jenn-Ming Yang

    2008-01-01

    The fatigue crack growth rate in notched fiber metal laminates under constant amplitude fatigue loading was studied analytically and experimentally. An analytical approach was used for predicting the crack growth rate with an empirical Paris-type equation, where the effective stress intensity factor in the metal layer is modulated by a bridging factor. The dimensionless bridging factor is calculated by the

  6. Fiber metal laminates: An advanced material for future aircraft

    Microsoft Academic Search

    A. Asundi; Alta Y. N. Choi

    1997-01-01

    Fiber Metal Laminates (FML) consist of thin, high strength aluminium alloy sheets alternately bonded to plies of fiber-reinforced epoxy adhesive. They provide an ideal combination of metals and composites that results in a material, which combines the best features of organic matrix composites and metals, without sharing their individual disadvantages. FML offer substantial weight savings relative to current metallic structures.

  7. Residual strength of metal-matrix laminated panels

    SciTech Connect

    Wu, M. [Failure Analysis Associates, Inc., Menlo Park, CA (United States). Mechanics and Materials Dept.; Wilson, D. [Tennessee Technological Univ., Cookeville, TN (United States). Mechanical Engineering Dept.

    1997-12-31

    The primary objective of this study was to investigate the residual strength of ARALL-3 and GLARE-2 center-notched panels without stiffeners. The R-curve approach in linear elastic fracture mechanics (LEFM) was used for the residual strength predictions. The applicability of LEFM was verified through a series of tests of ARALL-3 and GLARE-2 center-notched panels with different layups. They demonstrated limited crack-tip plastic deformation. The R-curves calculated from the tests of different size panels with various initial crack extensions showed that they were independent of initial crack length and specimen width, which is true for the monolithic aluminum alloy. Polynomial curve fitting was used to obtain the R-curves for each laminate and laminate layup to be used for the R-curve residual strength predictions. The predictions were made by superimposing the crack driving force curves onto these R-curves to locate the tangent points. The results of prediction of unidirectional fiber/metal laminates proved that the R-curve approach was not only a suitable but simple method that has a great potential in the damage tolerance characterization of certain unstiffened and stiffened laminate materials.

  8. Experimental Tests Analysis of Fiber Metal Laminate under Birdstrike

    Microsoft Academic Search

    M. Guida; F. Marulo; M. Meo; S. Russo

    2012-01-01

    The work is based on the experimental activities developed to investigate the behavior of fiber metal laminate (FML) materials used for very critical structural components, such as leading edge panels, that must satisfy a series of requirements defined in terms of structural resistance, applying impact loads at different speeds, arising, for example, from birdstrike on wing leading edge.The experimental tests

  9. Numerical modeling for thermographic inspection of fiber metal laminates

    Microsoft Academic Search

    F. Mabrouki; M. Genest; G. Shi; A. Fahr

    2009-01-01

    This study combines experiments and finite element analysis to assess the capabilities and limitations of both pulsed and lock-in thermography for the detection of delaminations in fiber metal laminate (FML) panels. The assessment is based on the minimum detectable defect size and the maximum depth at which a defect can be detected. Based on experimental validation, a finite element model

  10. THERMAL ANALYSIS COMPUTATION AND EXPERIMENTAL VALIDATION OF FIBER METAL LAMINATES

    Microsoft Academic Search

    J. Teßmer; S. Waitz; R. Rolfes; J. Ackva; T. de Vries

    Fiber Metal Laminates (FML) are well suited for high performance structures, e.g. in aeronautics. Despite their great mechanical potential, they already suffer a decrease of material strength at temperatures that are likely to occur on a standard flight profile. Therefore, an accurate thermal analysis is important, if dimensioning load cases occur at elevated temperatures. Within this paper the modeling of

  11. Bending behavior of shape memory polymer based laminates

    Microsoft Academic Search

    Chun-Sheng Zhang; Qing-Qing Ni

    2007-01-01

    Shape memory polymers (SMP) are smart materials was characterized by the recoverability of shape memory effect, but its mechanical property such as the strength is low. In this study, for industrial applications, a carbon fiber fabric reinforced shape memory polymer was developed. Four kinds of specimens with different laminations of carbon fiber fabric and shape memory polymer sheet were prepared.

  12. Organic light-emitting diodes formed by soft contact lamination

    Microsoft Academic Search

    Tae-Woo Lee; Jana Zaumseil; Zhenan Bao; Julia W. P. Hsu; John A. Rogers

    2004-01-01

    Although tremendous progress has been made in organic light-emitting diodes (OLEDs), with few exceptions they are fabricated in the standard way by sequentially depositing active layers and electrodes onto a substrate. Here we describe a different approach for building OLEDs, which is based on physical lamination of thin metal electrodes supported by an elastomeric layer against an electroluminescent organic. This

  13. Genetic optimization of two-material composite laminates Laurent Grosset

    E-print Network

    Coello, Carlos A. Coello

    Genetic optimization of two-material composite laminates Laurent Grosset , Satchi Venkataraman@aero.ufl.edu) Post-Doctoral Associate (satchi@aero.ufl.edu) Distinguished Professor, Fellow AIAA (haftka & Engineering Science, University of Florida, P.O.Box 116250, Gainesville, FL 32611, USA Satchi Venkataraman

  14. Mechanical performance of fiberglass laminates for sucker rod applications

    SciTech Connect

    Gauchel, J.V.

    1985-01-01

    This paper presents the results of a program designed to evaluate the tensile, shear, and tensile/tensile fatigue performance versus temperature of typical FRP pultruded laminates used in sucker rods. The predictability of performance and its sensitivity to process conditions will also be discussed.

  15. 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.

  16. Development of Angle Ply Cement Based Composite Laminates

    E-print Network

    Mobasher, Barzin

    as shown in Figure 2. The impregnation chamber consists of a tube filled with cement paste that coatsDevelopment of Angle Ply Cement Based Composite Laminates A. Pivacek, G. J. Haupt, and B. Mobasher cement based materials with improved structural and mechanical properties are developed. High fiber

  17. FINITE ELEMENT MODELING OF RC CONNECTIONS STRENGTHENED WITH FRP LAMINATES

    Microsoft Academic Search

    D. MOSTOFINEJAD; S. B. TALAEITABA

    Use of fiber reinforced plastic (FRP) composites for strengthening of beams and columns in RC structures has attracted great attention in recent decades. However, less attention has been paid to strengthening RC connections with FRP laminates. In the current study, a finite element (FE) modeling has been proposed for the non-linear analysis of RC joints covered with FRP overlays. The

  18. Passive damage detection in composite laminates with integrated sensing networks

    Microsoft Academic Search

    Yi Huang; Fabrizia Ghezzo; Patrick Rye; Sia Nemat-Nasser

    2008-01-01

    The initiation and propagation of damage in composite laminates generate Acoustic Emission. The use of real time AE monitoring has been quite extensive for in-service composite structures. In the present work, experimental and numerical studies were performed to characterize the acoustic wave propagation in thin glass\\/epoxy composite plates. Experimentally obtained and simulated emission signals were used to identify and locate

  19. Damage in woven CFRP laminates subjected to low velocity impacts

    NASA Astrophysics Data System (ADS)

    Ullah, H.; Abdel-Wahab, A. A.; Harland, A. R.; Silberschmidt, V. V.

    2012-08-01

    Carbon fabric-reinforced polymer (CFRP) composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution in these materials affects both their in-service properties and performance that can deteriorate with time. These processes need adequate means of analysis and investigation, the major approaches being experimental characterisation and non-destructive examination of internal damage in composite laminates. This research deals with a deformation behaviour and damage in woven composite laminates due to low-velocity dynamic out-of-plane bending. Experimental tests are carried out to characterise the behaviour of such laminates under large-deflection dynamic bending in un-notched specimens in Izod tests using a Resil Impactor. A series of low-velocity impact tests is carried out at various levels of impact energy to assess the energy absorbed and force-time response of CFRP laminates. X-ray micro computed tomography (micro-CT) is used to investigate material damage modes in the impacted specimens. X-ray tomographs revealed that through-thickness matrix cracking, inter-ply delamination and intra-ply delamination, such as tow debonding and fabric fracture, were the prominent damage modes.

  20. Thermal insulation, antibacterial and mold properties of breathable nanofiber-laminated wallpapers.

    PubMed

    Kim, Byoung-Suhk; Kimura, Naotaka; Kim, Han-Ki; Watanabe, Kei; Kim, Ick-Soo

    2011-06-01

    We studied the thermal insulation, antibacterial and mold properties of the nanofiber laminated wallpapers prepared by laminate-coating using electrospinning method. The thermal insulation capability of the nanofiber laminated wallpapers was evaluated by using a home-made insulated environmental chamber under different environmental conditions. It was found that the nanofiber laminated wallpapers exhibited better thermal insulation performance than the conventional silk wallpaper, which was commercialized silk wallpapers prepared by polyacrylic resin, suggesting that the laminate-coated nanofiber layer played an effective role in thermal insulation. Compared to the normal silk wallpaper, the nanofiber laminated wallpaper also exhibited good moisture vapor transmission rate (MVTR) due to excellent vapor permeability. In addition, TiO2-containing nanofiber laminated wallpapers exhibited good antibacterial activity against both E. Coli and P. Aeruginosa. PMID:21770124

  1. Paulsenella Chatton (Dinophyta), ectoparasites of marine diatoms: development and taxonomy

    NASA Astrophysics Data System (ADS)

    Drebes, G.; Schnepf, E.

    1988-09-01

    All members of the dinophyte Paulsenella are ectoparasites on marine planktonic diatoms. At present three species are known, two of which are described here for the first time. The taxonomy of the type species, P. chaetoceratis, is paid critical attention. The species are clearly distinguished by their host specificity and additionally by differences in morphology, especially of the trophonts. Using clonal cultures the life cycles of the three species are compared. The vegetative development may be interrupted by formation of temporary and resting cysts. In ageing cultures, stages with nuclear cyclosis occur, believed to indicate meiosis. In P. vonstoschii, the meiospores are capable of developing into resting cysts. As yet, knowledge on sexual reproduction is still incomplete.

  2. Inhibition of experimental autoimmune orchitis by fossil diatoms

    NASA Astrophysics Data System (ADS)

    Bustuoabad, Oscar D.; Meiss, Roberto P.; Molinolo, Alfredo R.; Mayer, Alejandro M. S.

    1985-06-01

    Experimental autoimmune orchitis (EAO) induced in Swiss mice could be reduced by means of the utilization of micronized frustules of fossil diatoms (DS) containing 54% of SiO2. Experimental mice were sensitized with testicular Antigen (Ag) in Complete Freund’s Adjuvant (CFA) inoculated twice, on day 0 and day 21. 100 ?g of DS suspension was inoculated into sensitized mice 10 times, once every 4 days, subcutaneously, starting on day 7 after the first Ag inoculation. Mice receiving the DS treatment showed a diminution of the delayed hypersensitivity reaction, lower antibody titer and decreased incidence of testicular injury as well as reduced grade and extension of the lesions. Possible explanation of these results would suggest alteration of monocyte and/or macrophage normal behaviour as well as alteration of antibody synthesis by different mechanisms.

  3. Priority effects in a planktonic bloom-forming marine diatom

    PubMed Central

    Sefbom, Josefin; Sassenhagen, Ingrid; Rengefors, Karin; Godhe, Anna

    2015-01-01

    Priority effects occur when a species or genotype with earlier arrival has an advantage such that its relative abundance in the community or population is increased compared with later-arriving species. Few studies have dealt with this concept in the context of within-species competition. Skeletonema marinoi is a marine diatom that shows a high degree of genetic differentiation between populations over small geographical distances. To test whether historical events such as priority effects may have been important in inducing these patterns of population differentiation, we performed microcosm experiments with successive inoculation of different S. marinoi strains. Our results show that even in the absence of a numerical advantage, significant priority effects were evident. We propose that priority effects may be an important mechanism in initiating population genetic differentiation. PMID:25948569

  4. Priority effects in a planktonic bloom-forming marine diatom.

    PubMed

    Sefbom, Josefin; Sassenhagen, Ingrid; Rengefors, Karin; Godhe, Anna

    2015-05-01

    Priority effects occur when a species or genotype with earlier arrival has an advantage such that its relative abundance in the community or population is increased compared with later-arriving species. Few studies have dealt with this concept in the context of within-species competition. Skeletonema marinoi is a marine diatom that shows a high degree of genetic differentiation between populations over small geographical distances. To test whether historical events such as priority effects may have been important in inducing these patterns of population differentiation, we performed microcosm experiments with successive inoculation of different S. marinoi strains. Our results show that even in the absence of a numerical advantage, significant priority effects were evident. We propose that priority effects may be an important mechanism in initiating population genetic differentiation. PMID:25948569

  5. Silaffins of Diatoms: From Applied Biotechnology to Biomedicine

    PubMed Central

    Pamirsky, Igor E.; Golokhvast, Kirill S.

    2013-01-01

    Silaffins are involved in the formation of the cell walls of diatoms. It is known that silaffins can precipitate silica in vitro, forming nano- and micro-particles in the shape of spheres and plates containing many pores. It is important to note that the deposition of silica and the particle morphology in the presence of silaffins affects chemical and physical agents (e.g., peptides, polyamines, phosphate, nitrogen, and the mechanical changes of the reaction mixture). It is believed that silaffins act as an organic matrix for silica-genesis and that silica pore size should reflect the pattern of a matrix. Here, biotechnology related to silaffins is discussed in the context of “a hypothesis of silaffin matrix” and “the LCPA-phosphate model”. We discuss the most promising area of silaffin biotechnology—the development of production methods for silicon structures with desired shapes and nanostructural properties that can be used to create biocompatible materials. PMID:24065158

  6. Spectral Analysis of Two Coupled Diatomic Rotor Molecules

    PubMed Central

    Crogman, Horace T.; Harter, William G.

    2014-01-01

    In a previous article the theory of frame transformation relation between Body Oriented Angular (BOA) states and Lab Weakly Coupled states (LWC) was developed to investigate simple rotor–rotor interactions. By analyzing the quantum spectrum for two coupled diatomic molecules and comparing it with spectrum and probability distribution of simple models, evidence was found that, as we move from a LWC state to a strongly coupled state, a single rotor emerges in the strong limit. In the low coupling, the spectrum was quadratic which indicates the degree of floppiness in the rotor–rotor system. However in the high coupling behavior it was found that the spectrum was linear which corresponds to a rotor deep in a well. PMID:25353181

  7. Spectral analysis of two coupled diatomic rotor molecules.

    PubMed

    Crogman, Horace T; Harter, William G

    2014-01-01

    In a previous article the theory of frame transformation relation between Body Oriented Angular (BOA) states and Lab Weakly Coupled states (LWC) was developed to investigate simple rotor-rotor interactions. By analyzing the quantum spectrum for two coupled diatomic molecules and comparing it with spectrum and probability distribution of simple models, evidence was found that, as we move from a LWC state to a strongly coupled state, a single rotor emerges in the strong limit. In the low coupling, the spectrum was quadratic which indicates the degree of floppiness in the rotor-rotor system. However in the high coupling behavior it was found that the spectrum was linear which corresponds to a rotor deep in a well. PMID:25353181

  8. Calculations of accommodation coefficients for diatomic molecular gases.

    PubMed

    Ambaye, Hailemariam; Manson, J R

    2006-03-01

    A theoretical study of energy and momentum accommodation coefficients and reduced force coefficients for molecular gases exchanging energy with surfaces has been carried out. The theoretical model uses classical mechanics for describing translational and rotational motions while internal molecular vibrational modes are treated quantum mechanically. Calculations for diatomic molecular gases are compared with recent measurements using hypersonic beams of N2 incident on SiO2 layers deposited on Kapton substrates. The theory gives good qualitative predictions of the behavior of the various accommodation coefficients as functions of the available experimentally controllable parameters such as incident translational energy, incident beam angle, molecular and surface masses, and surface temperature. Quantitative comparisons with measurements for energy and normal momentum accommodation indicate that these experiments can be used to obtain basic physical information about the molecule-surface interaction such as the physisorption potential well depth and the extent of surface roughness. PMID:16605510

  9. Topological edge plasmon modes between diatomic chains of plasmonic nanoparticles.

    PubMed

    Ling, C W; Xiao, Meng; Chan, C T; Yu, S F; Fung, K H

    2015-02-01

    We study the topological edge plasmon modes between two "diatomic" chains of identical plasmonic nanoparticles. Zak phase for longitudinal plasmon modes in each chain is calculated analytically by solutions of macroscopic Maxwell's equations for particles in quasi-static dipole approximation. This approximation provides a direct analogy with the Su-Schrieffer-Heeger model such that the eigenvalue is mapped to the frequency dependent inverse-polarizability of the nanoparticles. The edge state frequency is found to be the same as the single-particle resonance frequency, which is insensitive to the separation distances within a unit cell. Finally, full electrodynamic simulations with realistic parameters suggest that the edge plasmon mode can be realized through near-field optical spectroscopy. PMID:25836073

  10. Quantum Electrodynamical Corrections to Energy Levels of Diatomic Quasimolecules

    NASA Astrophysics Data System (ADS)

    Artemyev, A. N.; Surzhykov, A.

    2015-06-01

    We elaborate an ab initio approach for the evaluation of the one-loop quantum electrodynamical corrections to energy levels of diatomic quasimolecules. The approach accounts for the interaction between an electron and two nuclei in all orders in Z ? and can be applied for a wide range of internuclear distances, up to R ?1000 fm . Based on the developed theory, detailed calculations are performed for the self-energy and vacuum-polarization corrections to the energy of the 1 ?g ground state of the U92 +- U91 + dimer that can be produced in slow ion-ion collisions. The calculations predict the remarkable energy shift that arises due to the nonspherical contributions to the electron-nuclei potential taken beyond the standard monopole approximation.

  11. Variable frequency microwave (VFM) curing, processing of thermoset prepreg laminates. Final report

    SciTech Connect

    Paulauskas, F.L.

    1996-09-30

    The objective of this work was to investigate the beneficial effect of the variable frequency microwave (VFM) technology to cure thermosetting prepreg laminates. Further, it was to investigate the interrelationship and effect on the curing process of frequency, band width, and curing time with different types of laminates. Previous studies of microwave-assisted curing of neat resins (epoxy) and unidirectional glass and carbon fiber laminates with a fixed frequency of 2.45 GHz, have shown that a substantial reduction in the curing time was obtained. Results of this earlier work indicate that the microwave-assisted curing of multidirectional glass fiber laminates also show a substantial reduction of the required curing time. This may be explained by the penetration of microwave energy directly and throughout the laminate with enhancement of the kinetics of the chemical reaction. The fixed frequency microwave radiation of 2.45 GHz has been demonstrated to be a partially acceptable method to cure unidirectional carbon fiber laminates. Multidirectional carbon fiber/epoxy laminates demonstrate a lack of coupling during the curing process. A direct curing of these laminates was not possible by microwave radiation with the experimental approach used in agreement with previous work. In addition to this short coming, the unidirectional laminate samples cured with the fixed frequency are visually nonuniform. Localized areas of darker colors (burn, hot spots, overheating) are attributed to the formation of standing waves within the microwave cavity. For this reason, the laminates are subject to proper rotation while curing through fixed frequency. The present research indicates that variable frequency microwave technology is a sound and acceptable processing method to effectively cure uni-, bi- or multi-directional thermosetting glass fiber laminates. Also, this methodology will effectively cure unidirectional thermosetting carbon fiber laminates. For all these cases, this technology yielded a substantial reduction in the required cure time of these laminates. Multidirectional carbon fiber laminates demonstrated a lack of coupling of VFM energy during the curing process.

  12. Shear degradation in fiber reinforced laminates due to matrix damage

    NASA Astrophysics Data System (ADS)

    Salavatian, Mohammedmahdi

    The objective of this study was to develop and implement a shear modulus degradation model to improve the failure analysis of the fiber reinforced composite structures. Matrix damage, involving transverse and shear cracks, is a common failure mode for composite structures, yet little is known concerning their interaction. To understand the material behavior after matrix failure, the nonlinear response of the composite laminate was studied using pressure vessels made from a [+/-o] bias orientation, which tend to exhibit a matrix dominated failure. The result of this work showed laminate matrix hardening in shear and softening in the transverse direction. A modified Iosipescu coupon was proposed to study the evolution of shear and transverse damage and their mutual effects. The proposed method showed good agreement with tubular results and has advantages of simplified specimen fabrication using standard test fixtures. The proposed method was extended by introducing a novel experimental technique to study the shear degradation model under biaxial loading. Experimental results of the transverse modulus reduction were in good agreement with material degradation models, while the predicted shear modulus reduction was higher than experiment. The discrepancy between available models and observations was due to the presence of a traction between the crack surfaces. Accordingly, a closed form solution was proposed for the shear stress-strain field of a cracked laminate by replacing the cracks with cohesive zones. The constitutive equations of the crack laminate were derived including the effects of internal tractions and transverse stress on the shear modulus. The proposed analytical model was shown to be the most comprehensive model for shear modulus degradation reduction of the fiber reinforced laminates. A numerical implementation of the shear degradation model was done using continuum damage mechanics. Through this work it was shown the common assumption of a linear relation between matrix damage variables do not sufficiently describe shear response. Therefore, a modified damage model for matrix failure was developed and implemented in ABAQUS using a UMAT subroutine.

  13. Nuclear spin-dependent parity nonconservation in diatomic molecules

    NASA Astrophysics Data System (ADS)

    Murphree, Dennis Haaga, Jr.

    Nuclear spin-dependent parity nonconserving phenomena produce effects that are relevant to particle, nuclear, and atomic physics. They unite these increasingly disparate disciplines via the subtle effects of the weak force. Currently, weak interactions between nucleons present at best a confusing picture, and neutral weak coupling of leptons to baryons, even at high energy, is one of the most poorly characterized aspects of the Standard Model. Perhaps surprisingly, one of the most effective laboratories for studying parity violation is the diatomic molecule. The naturally close spacing of molecular hyperfine-rotational levels, which can be Zeeman shifted even closer to degeneracy, allows small parity violating effects to be enhanced dramatically. Here we describe the beginning of our experimental program to study nuclear spin-dependent parity nonconservation (NSD-PNC) using a beam of diatomic free radicals. Specifically, we seek to measure weak matrix elements connecting hyperfine-rotational states in a series of molecules, beginning with barium fluoride. Our experimental technique is based on a Stark interference method: we look for asymmetries in transitions that depend on the sign of an applied electric field. A key element in the experimental program is the magnetic field used to Zeeman shift the levels in our molecules to near crossing. Carefully controlling both the strength and uniformity of this field is critical to the success of the experiment. In order to measure the field over the wide range of values required by our experiment, both a completely novel nuclear magnetic resonance probe, as well as a unique field shimming apparatus and algorithm, were developed. A second important element in the program is the ability to detect the states of our molecules with as high a signal to noise as possible. To that end a new detection method based on a two-photon transition was developed. Both of these areas, which constitute the bulk of the author's contribution to the experimental program, are described in detail.

  14. Marine diatoms sustain growth of bivalves in a Mediterranean lagoon

    NASA Astrophysics Data System (ADS)

    Pernet, Fabrice; Malet, Nathalie; Pastoureaud, Annie; Vaquer, André; Quéré, Claudie; Dubroca, Laurent

    2012-02-01

    Carbon stable isotopes and fatty acids were measured in the suspended particulate organic matter (POM) of the Thau lagoon to study its qualitative temporal changes in relation to environmental factors and to identify the food sources of bivalves over a one-yr-cycle in relation to their growth. Reciprocally, the impact of shellfish farming on POM was also studied. Oysters and mussels were sampled and measured for biometry, stable isotopes and fatty acid composition. Water samples were collected at two sites, both inside and outside of the shellfish farming area, to determine concentrations in POM, chlorophyll a (Chl a) and stable isotopes. Carbon isotopes and fatty acids in bivalves reflected seasonal changes in food sources, which varied consistently with the environment. Seasonal changes in ?13C and fatty acids in the bivalves suggested that dietary phytoplankton contribution varied according to season. Terrestrial organic matter and bacteria can contribute to the diet of bivalves during non-bloom periods. Mussels seemed to rely more on diatoms and less on terrestrial organic matter and bacteria than oysters did, particularly when phytoplankton biomass was low during the summer. Although one- and two-yr-old oysters showed similar ?13C, their fatty acid dynamics differed slightly. Periods of high growth rate in bivalves were mainly fuelled by diatoms, thus highlighting the importance of seasonal blooms of microphytoplankton during the critical period of bivalve growth and gamete production. Although there was no significant effect of shellfish farms on Chl a and POM ?13C, consistent differences indicate that stable isotopes could be used successfully to investigate the effects of bivalve aquaculture.

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

    E-print Network

    , environmental effects · Strength Based: standard joint geometryg j g y like lap shear; test includes crack Simulation Ic, IIc #12;3. Blade adhesives · Bulk adhesive strength, fatigue,g , g , fracture toughness;5. Property Data for Analysis · 3-D static properties of 100 mm thick glass/epoxy Laminate Elastic Constants1

  16. Diatoms and Other Epibionts Associated with Olive Ridley (Lepidochelys olivacea) Sea Turtles from the Pacific Coast of Costa Rica

    PubMed Central

    Majewska, Roksana; Santoro, Mario; Bolaños, Federico; Chaves, Gerardo; De Stefano, Mario

    2015-01-01

    Although the sea turtles have long been familiar and even iconic to marine biologists, many aspects of their ecology remain unaddressed. The present study is the first of the epizoic diatom community covering the olive ridley turtle’s (Lepidochelys olivacea) carapace and the first describing diatoms living on sea turtles in general, with the primary objective of providing detailed information on turtle epibiotic associations. Samples of turtle carapace including the associated diatom biofilm and epizoic macro-fauna were collected from Ostional beach (9° 59´ 23.7´´ N 85° 41´ 52.6´´ W), Costa Rica, during the arribada event in October 2013. A complex diatom community was present in every sample. In total, 11 macro-faunal and 21 diatom taxa were recorded. Amongst diatoms, the most numerous were erect (Achnanthes spp., Tripterion spp.) and motile (Haslea sp., Navicula spp., Nitzschia spp., Proschkinia sp.) forms, followed by adnate Amphora spp., while the most common macro-faunal species was Stomatolepas elegans (Cirripedia). Diatom densities ranged from 8179 ± 750 to 27685 ± 4885 cells mm-2. Epizoic microalgae were either partly immersed or entirely encapsulated within an exopolymeric coat. The relatively low diatom species number, stable species composition and low inter-sample dissimilarities (14.4% on average) may indicate a mutualistic relationship between the epibiont and the basibiont. Dispersal of sea turtle diatoms is probably highly restricted and similar studies will help to understand both diatom diversity, evolution and biogeography, and sea turtle ecology and foraging strategies. PMID:26083535

  17. The Unusal Presence of Diatoms in Western North Atlantic Sediments during the Deglaciation

    NASA Astrophysics Data System (ADS)

    Gil, I. M.; Keigwin, L. D.; Abrantes, F. F. G.

    2014-12-01

    Since the North Atlantic flooding by southern sourced water (SSW) during the last deglaciation has likely promoted increased siliceous primary productivity and preservation, it is relevant to define its occurrence and its composition to assess how marine productivity conditions were modified. This work presents the study of the siliceous microfossil content of several cores from the western North Atlantic during the last deglaciation. Diatoms are mostly present during the Mystery Interval (here, 18.5 - 14.5 ka). At sites between 74ºN and 48ºN, part of the diatom record was composed by Ethmodiscus fragments and their abundance was notably increased during the first part of the interval. Then, the others marine diatom genera were more abundant and Ethmodiscus fragments even disappeared from the southern sites sediments. The ecologic specificities of Ethmodiscus vs other marine diatom genera will be discussed and compared with oxygen isotopes measurements to interpret the possible sequence of oceanographic processes involved.

  18. Optics with diatoms: towards efficient, bioinspired photonic devices at the micro-scale

    NASA Astrophysics Data System (ADS)

    De Tommasi, E.; Rea, I.; De Stefano, L.; Dardano, P.; Di Caprio, G.; Ferrara, M. A.; Coppola, G.

    2013-04-01

    Diatoms are monocellular algae responsible of 20-25% of the global oxygen produced by photosynthetic processes. The protoplasm of every single cell is enclosed in an external wall made of porous hydrogenated silica, the frustule. In recent times, many effects related to photonic properties of diatom frustules have been discovered and exploited in applications: light confinement induced by multiple diffraction, frustule photoluminescence applied to chemical and biochemical sensing, photonic-crystal-like behavior of valves and girdles. In present work we show how several techniques (e.g. digital holography) allowed us to retrieve information on light manipulation by diatom single valves in terms of amplitude, phase and polarization, both in air and in a cytoplasmatic environment. Possible applications in optical microsystems of diatom frustules and frustule-inspired devices as active photonic elements are finally envisaged.

  19. Diatoms and silicoflagellates of the Upper Cretaceous from Saratov Region: Biostratigraphy and sedimentation settings

    NASA Astrophysics Data System (ADS)

    Oreshkina, T. V.; Lygina, E. A.; Vozhzhova, O. A.; Ivanov, A. V.

    2013-03-01

    A representative assemblage of diatoms and silicoflagellates found in a excellent state of preservation is described from terrigenous cherty deposits of the Upper Cretaceous, which are exposed in a quarry near the Kologrivovka village in Saratov Region. The assemblage is correlative with diatoms of the Costopyxis antiqua Zone of the lower Campanian and with silicoflagellates of the Cornua trifurcata Zone, the upper one in the lower Campanian. According to the taxonomic composition, dominated by diatom genera Cortinocornus, Costopyxis, Hemiaulus, Paralia, Pseudopodosira, and Stephanopyxis, the assemblage was typical of a highly productive neritic zone with an active hydrological regime. A perceptible content of silicoflagellates among the diatoms suggests the normal salinity of the sedimentation basin. The comparable sedimentation settings in marginal parts of the Early Campanian epicontinental basin on the south of the East European platform can also be inferred based on the data from the lithological analysis.

  20. Radioisotopic Method for Measuring Cell Division Rates of Individual Species of Diatoms from Natural Populations †

    PubMed Central

    Rivkin, Richard B.

    1986-01-01

    Silicon is an essential element for diatom frustule synthesis and is usually taken up only by dividing cells. With 68Ge, a radioactive analog of Si, the cell cycle marker event of frustule formation was identified for individual species of diatom. The frequency of cells within a population undergoing this division event was estimated, and the cell division rate was calculated. In laboratory cultures, these rates of cell division and those calculated from changes in cell numbers were similar. By dual labeling with 68Ge(OH)4 and NaH14CO3, rates of cell division and photosynthesis were coincidently measured for diatoms both in laboratory cultures and when isolated from natural populations in estuarine, offshore, and polar environments. These techniques permit the coupling between photosynthesis and cell division to be examined in situ for individual species of diatom. PMID:16347039