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  • 1
    Electronic Resource
    Electronic Resource
    Ozone-Induced Immobilization of Chitosan and Heparin on Polyethylene Terephthalate Films to Improve Antithrombogenic Properties (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 342-343 (July 2007), p. 809-812 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: of artificial blood catheters. This paper describes the immobilization of chitosan andheparin molecules on polyethylene terephthalate (PET) films by ozonization. The concentration ofperoxide groups (-OOH) was 1.72 × 10-7 mol/cm2 on the PET surface oxidized by ozonization.The results of X-ray photoelectron spectroscopy (XPS) indicate that chains of chitosan and heparinwere successfully immobilized on the PET films. The static contact angle(STA) of waterdecreases from 83.5° to 68.3° by immobilization of chitosan and heparin, which means that thehydrophilic properties of the modified PET is improved. The antithrombogenic property of PETsurface was evaluated by a platelet-rich plasma (PRP) adhesion test. The results indicate that thenumber of platelet adhered on the modified-PET surface incubated with PRP for 240 min decreasedsignificantly and platelets did not aggregate and distort
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.342-343.809.pdf
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The impact of surface-adsorbed phosphorus on phytoplankton Redfield stoichiometry (2004)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 432 (2004), S. 897-901 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Redfield ratio of 106 carbon:16 nitrogen:1 phosphorus in marine phytoplankton is one of the foundations of ocean biogeochemistry, with applications in algal physiology, palaeoclimatology and global climate change. However, this ratio varies substantially in response to changes in algal ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature03125
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Factors affecting N2 fixation by the cyanobacterium Trichodesmium sp. GBRTRLI101 (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 45 (2003), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Various factors affecting N2 fixation of a cultured strain of Trichodesmium sp. (GBRTRLI101) from the Great Barrier Reef Lagoon were investigated. The diurnal pattern of N2 fixation demonstrated that it was primarily light-induced although fixation continued to occur for at least 1 h in the dark in samples that had been actively fixing N2. N2 fixation was dependent on the light intensity and stimulated more by white light when compared with blue, green, yellow and red light whereas rates of N2 fixation decreased most under red light. Inorganic phosphorous concentrations in the lower range of treatments up to 1.2 μM significantly stimulated N2 fixation and further additions promoted little or no increase in N2 fixation. Organic phosphorous (Na-glycerophosphate) also stimulated N2 fixation rates. Added combined nitrogen (NH4+, NO3−, urea) of 10 μM did not inhibit N2 fixation in short-term studies (first generation), however it was depressed in the long-term studies (fifth generation).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0168-6496(03)00157-0
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  • 4
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    Irreversibly increased nitrogen fixation in Trichodesmium experimentally adapted to elevated carbon dioxide (2015)
    Nature Publishing Group
    Details
    Publication Date: 2022-05-25
    Description: This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 6 (2015): 8155, doi:10.1038/ncomms9155.
    Description: Nitrogen fixation rates of the globally distributed, biogeochemically important marine cyanobacterium Trichodesmium increase under high carbon dioxide (CO2) levels in short-term studies due to physiological plasticity. However, its long-term adaptive responses to ongoing anthropogenic CO2 increases are unknown. Here we show that experimental evolution under extended selection at projected future elevated CO2 levels results in irreversible, large increases in nitrogen fixation and growth rates, even after being moved back to lower present day CO2 levels for hundreds of generations. This represents an unprecedented microbial evolutionary response, as reproductive fitness increases acquired in the selection environment are maintained after returning to the ancestral environment. Constitutive rate increases are accompanied by irreversible shifts in diel nitrogen fixation patterns, and increased activity of a potentially regulatory DNA methyltransferase enzyme. High CO2-selected cell lines also exhibit increased phosphorus-limited growth rates, suggesting a potential advantage for this keystone organism in a more nutrient-limited, acidified future ocean.
    Description: Grant support was provided by U.S. National Science Foundation OCE 1260490 and OCE 1143760 to D.A.H., E.A.W., and F.-X.F, and OCE 1260233, OCE OA 1220484, and G.B. Moore Foundation 3782 and 3934 to M.A.S.© The Author(s), [year].
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 5
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    Functional genomics and phylogenetic evidence suggest genus-wide cobalamin production by the globally distributed marine nitrogen fixer Trichodesmium (2018)
    Frontiers Media
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 9 (2018): 189, doi:10.3389/fmicb.2018.00189.
    Description: Only select prokaryotes can biosynthesize vitamin B12 (i.e., cobalamins), but these organic co-enzymes are required by all microbial life and can be vanishingly scarce across extensive ocean biomes. Although global ocean genome data suggest cyanobacteria to be a major euphotic source of cobalamins, recent studies have highlighted that 〉95% of cyanobacteria can only produce a cobalamin analog, pseudo-B12, due to the absence of the BluB protein that synthesizes the α ligand 5,6-dimethylbenzimidizole (DMB) required to biosynthesize cobalamins. Pseudo-B12 is substantially less bioavailable to eukaryotic algae, as only certain taxa can intracellularly remodel it to one of the cobalamins. Here we present phylogenetic, metagenomic, transcriptomic, proteomic, and chemical analyses providing multiple lines of evidence that the nitrogen-fixing cyanobacterium Trichodesmium transcribes and translates the biosynthetic, cobalamin-requiring BluB enzyme. Phylogenetic evidence suggests that the Trichodesmium DMB biosynthesis gene, bluB, is of ancient origin, which could have aided in its ecological differentiation from other nitrogen-fixing cyanobacteria. Additionally, orthologue analyses reveal two genes encoding iron-dependent B12 biosynthetic enzymes (cbiX and isiB), suggesting that iron availability may be linked not only to new nitrogen supplies from nitrogen fixation, but also to B12 inputs by Trichodesmium. These analyses suggest that Trichodesmium contains the genus-wide genomic potential for a previously unrecognized role as a source of cobalamins, which may prove to considerably impact marine biogeochemical cycles.
    Description: This work was funded by NSF research grants OCE-1260233, OCE-1260490, OCE-1657757, and OCE-143566.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
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    Mechanisms of increased Trichodesmium fitness under iron and phosphorus co-limitation in the present and future ocean (2016)
    Nature Publishing Group
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 7 (2016): 12081, doi:10.1038/ncomms12081.
    Description: Nitrogen fixation by cyanobacteria supplies critical bioavailable nitrogen to marine ecosystems worldwide; however, field and lab data have demonstrated it to be limited by iron, phosphorus and/or CO2. To address unknown future interactions among these factors, we grew the nitrogen-fixing cyanobacterium Trichodesmium for 1 year under Fe/P co-limitation following 7 years of both low and high CO2 selection. Fe/P co-limited cell lines demonstrated a complex cellular response including increased growth rates, broad proteome restructuring and cell size reductions relative to steady-state growth limited by either Fe or P alone. Fe/P co-limitation increased abundance of a protein containing a conserved domain previously implicated in cell size regulation, suggesting a similar role in Trichodesmium. Increased CO2 further induced nutrient-limited proteome shifts in widespread core metabolisms. Our results thus suggest that N2-fixing microbes may be significantly impacted by interactions between elevated CO2 and nutrient limitation, with broad implications for global biogeochemical cycles in the future ocean.
    Description: Grant support was provided by U.S. National Science Foundation OCE 1260490 to D.A.H., E.A.W. and F.-X.F., and OCE OA 1220484 and G.B. Moore Foundation 3782 and 3934 to M.A.S.
    Repository Name: Woods Hole Open Access Server
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  • 7
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    Subunit conformational variation within individual GroEL oligomers resolved by Cryo-EM (2017)
    National Academy of Sciences
    Details
    Publication Date: 2017-07-14
    Description: Single-particle electron cryo-microscopy (cryo-EM) is an emerging tool for resolving structures of conformationally heterogeneous particles; however, each structure is derived from an average of many particles with presumed identical conformations. We used a 3.5-Å cryo-EM reconstruction with imposed D7 symmetry to further analyze structural heterogeneity among chemically identical subunits in each GroEL oligomer. Focused classification of the 14 subunits in each oligomer revealed three dominant classes of subunit conformations. Each class resembled a distinct GroEL crystal structure in the Protein Data Bank. The conformational differences stem from the orientations of the apical domain. We mapped each conformation class to its subunit locations within each GroEL oligomer in our dataset. The spatial distributions of each conformation class differed among oligomers, and most oligomers contained 10–12 subunits of the three dominant conformation classes. Adjacent subunits were found to more likely assume the same conformation class, suggesting correlation among subunits in the oligomer. This study demonstrates the utility of cryo-EM in revealing structure dynamics within a single protein oligomer.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 8
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    Tracking the global maximum power point of a photovoltaic system under partial shading conditions using a modified firefly algorithm (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-05-05
    Description: Under partial shading conditions, the power–voltage (P-U) curve may exhibit multiple local maxima. This makes it challenging to track the global maximum power point (GMPP). Additionally, in such conditions, conventional maximum power point tracking (MPPT) methods cannot be used to extract the GMPP. This paper describes a modified firefly algorithm (MFA) that can rapidly and accurately extract the GMPP under partial shading conditions. The algorithm introduces the concepts of the global and local firefly densities during each iteration, and devises two elimination mechanisms to adaptively adjust the firefly population. The proposed method is compared with the traditional MPPT algorithms under four different partial shading conditions. Simulation results demonstrate that the MFA can immediately and accurately track the global maximum under the partially shaded conditions, and that the proposed method outperforms conventional techniques in terms of tracking efficiency and speed.
    Electronic ISSN: 1941-7012
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by American Institute of Physics (AIP)
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  • 9
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    Origin of interfacial polar order in incipient ferroelectrics (2015)
    American Physical Society (APS)
    Details
    Publication Date: 2015-05-13
    Description: Author(s): Yijia Gu, Nan Wang, Fei Xue, and Long-Qing Chen There are ample experimental evidences indicating that the ferroelastic domain walls of incipient ferroelectrics, such as SrTi O 3 and CaTi O 3 , are polar. The emergence of such interfacial polar order at a domain wall is exciting and believed to arise from the coupling between a primary order parameter... [Phys. Rev. B 91, 174103] Published Mon May 11, 2015
    Keywords: Structure, structural phase transitions, mechanical properties, defects
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
    Published by American Physical Society (APS)
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  • 10
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    Energies, Vol. 8, Pages 3628-3639: Application of a Backfilling Method in Coal Mining to Realise an Ecologically Sensitive “Black Gold” Industry (2015)
    MDPI Publishing
    In: Energies
    Details
    Publication Date: 2015-04-30
    Description: China, as the largest coal-producing and -consuming country in the world, is highly dependent on its coal industry, or “Black Gold” industry, for the national energy and economy. The consequent environmental crises, however, have persisted for decades, and the most serious effect is surface subsidence induced by underground mining. Underground coal excavation in China has ignored this problem for thousands of years, even though it causes conspicuous damage to the surface ecosystem and construction projects due to the subsidence of overlying strata. This study recommends paste backfilling to replace the space originally occupied by coal resources to avoid such subsidence and proposes backfilling schemes for two mainstream mining methods used in China’s collieries, namely, continuous mining and fully mechanised coal mining. These methodologies have been successfully implemented in some collieries, and the gob area can be backfilled immediately to prevent surface subsidence. To promote an ecological ideology when conflict exists between economic profits and environmental protection, experience from developed countries should be considered, support and appropriate legislation from the government are essential, and the perspective of colliery managers should be taken into account, and further in-depth study on strata subsidence and backfilling material must be pursued.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI Publishing
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