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  • 1
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    Effects of ocean acidification on Posidonia oceanica epiphytic community and shoot productivity (2015)
    PANGAEA
    In:  Supplement to: Cox, T Erin; Schenone, Stefano; Delille, Jeremy; Díaz-Castañeda, Victoria; Alliouane, Samir; Gattuso, Jean-Pierre; Gazeau, Frédéric (2015): Effects of ocean acidification on Posidonia oceanica epiphytic community and shoot productivity. Journal of Ecology, 103(6), 1594-1609, https://doi.org/10.1111/1365-2745.12477
    Details
    Publication Date: 2024-03-15
    Description: 1. Biological interactions can alter predictions that are based on single-species physiological response. It is known that leaf segments of the seagrass Posidonia oceanica will increase photosynthesis with lowered pH, but it is not clear whether the outcome will be altered when the whole plant and its epiphyte community, with different respiratory and photosynthetic demands, are included. In addition, the effects on the Posidonia epiphyte community have rarely been tested under controlled conditions, at near-future pH levels. 2. In order to better evaluate the effects of pH levels as projected for the upcoming decades on seagrass meadows, shoots of P. oceanica with their associated epiphytes were exposed in the laboratory to three pH levels (ambient: 8.1, 7.7 and 7.3, on the total scale) for 4 weeks. Net productivity, respiration, net calcification and leaf fluorescence were measured on several occasions. At the end of the study, epiphyte community abundance and composition, calcareous mass and crustose coralline algae growth were determined. Finally, photosynthesis vs. irradiance curves (PE) was produced from segments of secondary leaves cleaned of epiphytes and pigments extracted. 3. Posidonia leaf fluorescence and chlorophyll concentrations did not differ between pH treatments. Net productivity of entire shoots and epiphyte-free secondary leaves increased significantly at the lowest pH level yet limited or no stimulation in productivity was observed at the intermediate pH treatment. Under both pH treatments, significant decreases in epiphytic cover were observed, mostly due to the reduction of crustose coralline algae. The loss of the dominant epiphyte producer yet similar photosynthetic response for epiphyte-free secondary leaves and shoots suggests a minimal contribution of epiphytes to shoot productivity under experimental conditions. 4. Synthesis. Observed responses indicate that under future ocean acidification conditions foreseen in the next century an increase in Posidonia productivity is not likely despite the partial loss of epiphytic coralline algae which are competitors for light. A decline in epiphytic cover could, however, reduce the feeding capacity of the meadow for invertebrates. In situ long-term experiments that consider both acidification and warming scenarios are needed to improve ecosystem-level predictions.
    Keywords: Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Aragonite saturation state, standard deviation; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (〈20 L); Calcification/Dissolution; Calcite saturation state; Calcite saturation state, standard deviation; Calculated using seacarb; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; Community composition and diversity; Counts; Counts, standard deviation; Coverage; Description; Effective quantum yield; Effective quantum yield, standard error; Electron transport rate, relative; Electron transport rate, relative, standard error; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Group; Infrared gas analyzer; Irradiance; Irradiance, standard error; Laboratory experiment; Leaf net production, oxygen; Leaf net production, oxygen, standard error; Light saturation point; Light saturation point, standard error; Macroalgae; Maximal electron transport rate, relative; Maximal electron transport rate, relative, standard error; Maximum potential capacity of photosynthesis, oxygen; Maximum potential capacity of photosynthesis, oxygen , standard error; Mediterranean Sea; Net calcification rate of calcium carbonate; Net calcification rate of calcium carbonate, standard error; Net primary production of oxygen; Net primary production of oxygen, standard error; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Photosynthetic quantum efficiency; Photosynthetic quantum efficiency, standard error; Plantae; Posidonia oceanica; Potentiometric; Potentiometric titration; Primary production/Photosynthesis; Ratio; Registration number of species; Replicates; Respiration; Respiration rate, oxygen; Respiration rate, oxygen, standard error; Salinity; Saturation light intensity; Saturation light intensity, standard error; Single species; Species; Taxon/taxa; Temperate; Temperature, water; Temperature, water, standard deviation; Time point, descriptive; Tracheophyta; Treatment; Type; Uniform resource locator/link to reference; Villefranche_OA
    Type: Dataset
    Format: text/tab-separated-values, 13278 data points
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  • 2
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    Seawater carbonate chemistry and Posidonia oceanica epiphytic community composition and mineralogy (2017)
    PANGAEA
    In:  Supplement to: Cox, T Erin; Nash, Merinda C; Gazeau, Frédéric; Deniel, M; Legrand, Erwann; Alliouane, Samir; Mahacek, Paul; Le Fur, Arnaud; Gattuso, Jean-Pierre; Martin, Sophie (2017): Effects of in situ CO2 enrichment on Posidonia oceanica epiphytic community composition and mineralogy. Marine Biology, 164(5), https://doi.org/10.1007/s00227-017-3136-7
    Details
    Publication Date: 2024-03-15
    Description: Alterations in seagrass epiphytic communities are expected under future ocean acidification conditions, yet this hypothesis has been little tested in situ. A Free Ocean Carbon Dioxide Enrichment system was used to lower pH by a ~0.3 unit offset within a partially enclosed portion (1.7 m3) of a Posidonia oceanica meadow (11 m depth) between June 21 and November 3, 2014. Leaf epiphytic community composition (% cover) and bulk epiphytic mineralogy were compared every 4 weeks within three treatments, located in the same meadow: a pH-manipulated (experimental enclosure) and a control enclosure, as well as a nearby ambient area. Percent coverage of invertebrate calcifiers and crustose coralline algae (CCA) did not appear to be affected by the lowered pH. Furthermore, fleshy algae did not proliferate at lowered pH. Only Foraminifera, which covered less than 3% of leaf surfaces, declined in manner consistent with ocean acidification predictions. Bulk epiphytic magnesium carbonate composition was similar between treatments and percentage of magnesium appeared to increase from summer to autumn. CCA did not exhibit any visible skeleton dissolution or mineral alteration at lowered pH and carbonate saturation state. Negative impacts from ocean acidification on P. oceanica epiphytic communities were smaller than expected. Epiphytic calcifiers were possibly protected from the pH treatment due to host plant photosynthesis inside the enclosure where water flow is slowed. The more positive outcome than expected suggests that calcareous members of epiphytic communities may find refuge in some conditions and be resilient to environmentally relevant changes in carbonate chemistry.
    Keywords: Alkalinity, total; Aragonite; Aragonite saturation state; Asymmetry; Benthos; Bicarbonate ion; Calcite saturation state; Calcium carbonate mass; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; Community composition and diversity; Coverage; Entire community; EXP; Experiment; Field experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Magnesium carbonate, magnesite; Mediterranean Sea; Mesocosm or benthocosm; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Salinity; Salinity, standard deviation; Soft-bottom community; Temperate; Temperature, water; Temperature, water, standard deviation; Time point, descriptive; Treatment; Type; Villefranche_eFOCE
    Type: Dataset
    Format: text/tab-separated-values, 11028 data points
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  • 3
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    Effects of in situ CO2 enrichment on structural characteristics, photosynthesis, and growth of the Mediterranean seagrass Posidonia oceanica (2016)
    PANGAEA
    In:  Supplement to: Cox, T Erin; Gazeau, Frédéric; Alliouane, Samir; Hendriks, Iris; Mahacek, Paul; Le Fur, Arnaud; Gattuso, Jean-Pierre (2016): Effects of in situ CO2 enrichment on structural characteristics, photosynthesis, and growth of the Mediterranean seagrass Posidonia oceanica. Biogeosciences, 13(7), 2179-2194, https://doi.org/10.5194/bg-13-2179-2016
    Details
    Publication Date: 2024-03-15
    Description: Seagrass is expected to benefit from increased carbon availability under future ocean acidification. This hypothesis has been little tested by in situ manipulation. To test for ocean acidification effects on seagrass meadows under controlled CO2/pH conditions, we used a Free Ocean Carbon Dioxide Enrichment (FOCE) system which allows for the manipulation of pH as continuous offset from ambient. It was deployed in a Posidonia oceanica meadow at 11 m depth in the Northwestern Mediterranean Sea. It consisted of two benthic enclosures, an experimental and a control unit both 1.7 m**3, and an additional reference plot in the ambient environment (2 m**2) to account for structural artifacts. The meadow was monitored from April to November 2014. The pH of the experimental enclosure was lowered by 0.26 pH units for the second half of the 8-month study. The greatest magnitude of change in P. oceanica leaf biometrics, photosynthesis, and leaf growth accompanied seasonal changes recorded in the environment and values were similar between the two enclosures. Leaf thickness may change in response to lower pH but this requires further testing. Results are congruent with other short-term and natural studies that have investigated the response of P. oceanica over a wide range of pH. They suggest any benefit from ocean acidification, over the next century (at a pH of 7.7 on the total scale), on Posidonia physiology and growth may be minimal and difficult to detect without increased replication or longer experimental duration. The limited stimulation, which did not surpass any enclosure or seasonal effect, casts doubts on speculations that elevated CO2 would confer resistance to thermal stress and increase the buffering capacity of meadows.
    Keywords: Alkalinity, total; Aragonite saturation state; Aragonite saturation state, standard deviation; Benthos; Bicarbonate ion; Biomass, wet mass, standard deviation; Biomass, wet mass per area; Biomass/Abundance/Elemental composition; Calcite saturation state; Calcite saturation state, standard deviation; Calculated using seacarb; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; Color description; Compensation point; Compensation point, standard deviation; Coverage; Coverage, standard deviation; Date; Electron transport rate, relative; Electron transport rate, relative, standard deviation; EXP; Experiment; Field experiment; Figure; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Height; Height, standard deviation; Initial slope of rapid light curve; Initial slope of rapid light curve, standard deviation; Irradiance; Irradiance, standard deviation; Leaf area; Leaf area, standard deviation; Leaf density per shoot; Leaf length; Leaf length, standard deviation; Leaf production; Leaf production, standard deviation; Leaf toughness; Leaf toughness, standard deviation; Light saturation; Light saturation, standard deviation; Maximal electron transport rate, relative; Maximal electron transport rate, relative, standard deviation; Maximum gross photosynthesis rate, oxygen, per chlorophyll a; Maximum gross photosynthesis rate, oxygen, per chlorophyll a, standard deviation; Maximum photochemical quantum yield of photosystem II; Maximum photochemical quantum yield of photosystem II, standard deviation; Median absolute deviation; Mediterranean Sea; Mesocosm or benthocosm; Month; Net oxygen, flux per chlorophyll a; Number; OA-ICC; Ocean Acidification International Coordination Centre; Oxygen; Oxygen, flux, standard deviation; Oxygen, standard deviation; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Peyssonnelia sp.; pH; pH, standard deviation; pH change; Plantae; Plastochrone interval; Plastochrone interval, standard deviation; Posidonia oceanica; Potentiometric titration; Primary production/Photosynthesis; Registration number of species; Respiration; Respiration rate, oxygen, per chlorophyll a; Respiration rate, oxygen, standard deviation; Salinity; Salinity, standard deviation; Sample amount; Seagrass; Shoot density; Shoot density, standard deviation; Single species; Species; Spectrophotometric; Temperate; Temperature, water; Temperature, water, standard deviation; Thickness; Thickness, standard deviation; Time in days; Tracheophyta; Treatment; Type; Uniform resource locator/link to reference; Villefranche_eFOCE
    Type: Dataset
    Format: text/tab-separated-values, 13600 data points
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  • 4
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    Effects of in situ CO2 enrichment on epibiont settlement on artificial substrata within a Posidonia oceanica meadow (2017)
    PANGAEA
    Details
    Publication Date: 2024-03-15
    Description: Alterations to colonization or early post-settlement stages may cause the reorganization of communities under future ocean acidification conditions. Yet, this hypothesis has been little tested by in situ pH manipulation. A Free Ocean Carbon Dioxide Enrichment (FOCE) system was used to lower pH by a 0.3 unit offset within a partially enclosed portion (1.7 m**3) of a Posidonia oceanica seagrass meadow (11 m depth) between 21 June and 3 November 2014. Epibiont colonization and early post settlement stages were assessed within the FOCE setup, as part of the larger community-level study, to better understand the outcome for a multispecies assemblage and the ecological processes that result in reported community shifts under altered carbonate chemistry. Two types of artificial collectors (tiles and scourers) were placed within three treatments: a pH-manipulated enclosure, an un-manipulated control enclosure, and an open plot in the ambient meadow. Tiles and scourers were collected after one to four months. Additionally, to see whether the outcome differed for communities in a later successional stage, previously settled scourer-collectors were also placed in the same three treatments. Enclosures acted to reduce settlement and migrant colonization. Scourers deployed for one to four months within the open-plot contained a community assemblage that could be distinguished from the assemblages within the enclosures. However, a comparison of enclosure assemblages on tiles showed evidence of a pH effect. There was lowered coverage of crustose coralline algae and fewer calcareous tube-forming polychaetes (Spirorbis sp. and Spirobranchus sp.) on tiles placed in the pH-manipulated enclosure compared to the un-manipulated enclosure. For assemblages in scourer collectors, shared and common taxa, in all treatments, were invertebrate polychaetes Psamathe fusca, Sphaerosyllis sp., Chrysopetalum sp., arthropods Harpacticoida, and Amphipoda, and the juvenile bivalve Lyonsia sp. Similar organism composition and abundance, as well as taxonomic richness and evenness, were found in scourers from both enclosures. Pre-settled scourers contained greater numbers of individuals and more calcified members, but the assemblage, as well as the growth rate of a juvenile bivalve Lyonsia sp., appeared unaffected by a two-month exposure to lowered pH and calcium carbonate saturation state. Results from this case study support the hypothesis that early stages of specific calcifiers (crustose coralline algae and calcareous tube-forming polychaetes) are sensitive to near future ocean acidification conditions yet suggest that negative effects on sessile micro-invertebrate assemblages will be minimal.
    Keywords: Alkalinity, total; Aragonite saturation state; Aragonite saturation state, standard deviation; Benthos; Bicarbonate ion; Calcite saturation state; Calcite saturation state, standard deviation; Calculated using seacarb; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; Coverage; Coverage, standard deviation; Duration; Entire community; EXP; Experiment; Family; Field experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Identification; Individuals; Individuals, standard deviation; Mediterranean Sea; Mesocosm or benthocosm; OA-ICC; Ocean Acidification International Coordination Centre; Oxygen; Oxygen, standard deviation; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Phylum; Potentiometric titration; Proportion; Reproduction; Salinity; Salinity, standard deviation; Soft-bottom community; Spectrophotometric; Taxon/taxa; Temperate; Temperature, water; Temperature, water, standard deviation; Treatment; Type; Villefranche_eFOCE
    Type: Dataset
    Format: text/tab-separated-values, 57947 data points
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  • 5
    Electronic Resource
    Electronic Resource
    Modulation speed of an efficient porous silicon light emitting device (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 2764-2773 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Trends in the efficiency and small signal modulation behavior of porous silicon light emitting diodes (LEDs) are reported for devices formed by the anodization of bulk silicon p–n junctions. As the average size of the silicon skeleton is decreased, the external electroluminescence (EL) efficiency increases from 0.001% to 0.18% and there is a corresponding blue shift in the EL peak from 776 to 633 nm. An associated tenfold increase is observed in the photoluminescence efficiency while the diode resistance, at 2 V, increases from 3×103 to 1×106 Ω. Under small signal pulsed operation, the voltage dependence of the rising edge of the EL is well described by a carrier mobility of 3×10−4 cm2 s−1 V−1 which is independent of the average size of the luminescent regions of the silicon nanostructure. The falling edge of the EL transient is dominated by radiative recombination of quantum confined excitons. The modulation speed is found to be limited by a combination of carrier mobility in the silicon wires and radiative recombination processes. Evidence of charge trapping and discharge is found in an EL overshoot phenomenon. The major application of this type of porous silicon LED, with modulation speeds below 1 MHz, appears to be for displays integrated with circuitry rather than for optical interconnection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371123
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  • 6
    Electronic Resource
    Electronic Resource
    Spin-glass behavior of spinel iron oxide particles on iron metal particle recording media (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5853-5864 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Small (30 A(ring) diameter) spinel iron oxide particles which form the protective layer on acicular iron metal particle recording media are found to exhibit no observable magnetization. The typical experimental decrease in sample magnetization for several media specimens is about 3% from 5 to 300 K. This change is the same as the thermal decrease in metal core magnetization, determined by Mössbauer spectroscopy. The predicted decrease in sample magnetization assuming normal spinel oxide behavior is typically about 20%. Two intraparticle models for reduced magnetization in oxide nanoparticles are found to be incompatible with the magnetization data. An interparticle "super-spin-glass'' model is compatible with the magnetization data. The alignment between adjacent oxide nanoparticle moments is hypothesized to depend on the particular sublattices in contact, since the sublattice exchange interactions are all antiferromagnetic. An inverse particle size dependence is thus expected, in agreement with spinel oxide magnetization reduction and other phenomena seen in a wide range of studies on larger oxide particles and films. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359166
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  • 7
    Electronic Resource
    Electronic Resource
    Hc enhancement of Co-adsorbed γ-Fe2O3 particles via surface treatment with sodium polyphosphate : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5562-5564 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The coercive force HC of partially reduced, acicular γ-Fe2O3 particles having an adsorbed Co layer (4 wt % Co; Fe+2/Fe+3≈0.09; 2000 A(ring)×240 A(ring) particle dimensions; 36 m2/g specific surface area) increases substantially following surface treatment with (NaPO3)n≈14⋅Na2O. The maximum observed effect occurs at a polyphosphate-to-iron oxide weight ratio P/Fe near 0.5, denoted (P/Fe)max, where HC of the Co-adsorbed oxide increases from 687 to 1096 Oe immediately following treatment. The latter value increased to 1215 Oe after a four month storage in an argon environment containing less than 1 ppm H2O and O2, suggesting that the polyphosphate-oxide interaction is sensitive to moisture or oxygen. Co-adsorbed particles containing no Fe+2 in the oxide core also exhibit HC enhancement following surface treatment, but the change in HC is substantially less than that of particles containing Fe+2. The general behavior of polyphosphate-treated Co-adsorbed particles is observed to be similar to that of treated berthollide particles having no adsorbed Co layer: (i) the magnitude and sign of change in HC varies with P/Fe, reaching a peak value at (P/Fe)max, (ii) the magnitude of increase in HC at (P/Fe)max depends on the Fe+2 content of the particle core, (iii) saturation magnetization of the particles treated at (P/Fe)max is essentially unchanged from that of the untreated precursor, (iv) HC of specimens treated at (P/Fe)max returns to the value of the untreated precursor when the polyphosphate coating is removed via washing with water, and (v) particle dissolution occurs when P/Fe(very-much-greater-than)(P/Fe)max. Studies of anisotropy field distributions show that there is no obvious bimodal character to the very broad distribution of anisotropy fields found in randomly oriented specimens of surface-treated particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355689
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  • 8
    Electronic Resource
    Electronic Resource
    Efficient visible electroluminescence from highly porous silicon under cathodic bias (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2563-2565 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Visible electroluminescence (EL) has been obtained from porous silicon cathodically biased in an aqueous electrolyte containing either the persulphate or the peroxide ion. EL efficiencies of up to 0.1% have been obtained from porous silicon formed on both n-type and p-type substrates for the application of only a few volts bias. In subdued lighting, the EL is easily visible to the naked eye at excitation densities of 0.1 W cm−2. EL is obtained only from porous silicon capable of giving photoluminescence (PL); the EL and PL spectra are broadly similar in width and peak wavelength. The EL spectra are reversibly shifted to shorter wavelengths as the magnitude of the bias is increased. In contrast with the previously reported EL under anodic conditions, this cathodic EL process does not irreversibly oxidize the porous silicon skeleton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108127
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  • 9
    Electronic Resource
    Electronic Resource
    Relationship between storage media and blue photoluminescence for oxidized porous silicon (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 107-109 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Blue photoluminescence is observed, with nanosecond decay time, from rapid thermally oxidized porous silicon as a result of accelerated aging in plastic containers. Photoluminescence measurements, combined with chemical analyses of the "aged" porous silicon, indicate that the emission is a consequence of the incorporation of trace organic (hydrocarbon) contamination from the plastic containers as they outgas at a mildly elevated temperature (80 °C) and, albeit at a reduced rate, at room temperature. Such carbonaceous contaminants can subsequently be removed by high-temperature annealing, a process which also quenches the blue photoluminescence. Consequently, it is important to take into consideration the storage medium used when making comparative luminescent and compositional studies of porous silicon and, perhaps, porous materials in general. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119442
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  • 10
    Electronic Resource
    Electronic Resource
    Reproductive Behavior of Hexaploid/Diploid Wheat Hybrids (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 107 (1991), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The bottleneck restricting introgression of useful genes directly from diploid into hexaploid wheats is the low number of BC1F1 seeds obtained. In crosses between hexaploid wheat (Triticum aestivum L.; AABBDD) and Aegilops squarrosa L. (DD) or T. urartu Thum. (AA), this bottleneck may be overcome simply by pollinating a sufficient number of F1 spikes. However, hybrids between hexaploid wheat cultivars (T. aestivum) and T. monococcum L. (AA) generally are highly female-sterile, often having no pistils. One T. monococcum accession, PI 355520, when crossed with T. aestivum, produced hybrids with female fertility in the same range as that of T. aestivum/A. squarrosa or T. aestivum/T. urartu hybrids, ca. 0.5 to 1.0 backcross seed per spike. We found that female fertility was controlled by two duplicate genes in PI 355520, and that this accession can be used as a bridging parent to introgress genes from other T. monococcum accessions into hexaploid wheat. Pairing of homologous chromosomes was less frequent and weaker in such crosses than in T. aestivum/A. squarrosa crosses, but homoeologous bivalents occurred at a rate of almost 0.5 II per cell. Restitution division was detected in crosses involving all three diploid species and was confirmed cytologically in crosses with PI 355520. Chromosome numbers of BC1F1 plants ranged from 35 to 67; plants with 49 or more chromosomes occurred at frequencies of 0.09 to 0.21 among progeny of A. squarrosa and T. urartu and 0.29 in progeny of T. aestivum/T. monococcum crosses involving PI 355520. These results are consistent with those of previous studies, demonstrating the potential of direct Hexaploid/diploid crosses for rapidly introgressing useful genes into Hexaploid wheat with minimum disturbance of the background genotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1991.tb00537.x
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