THE KAUST Repository is an initiative of the University Library to expand the impact of conference papers, technical reports, peer-reviewed articles, preprints, theses, images, data sets, and other research-related works of King Abdullah University of Science and Technology (KAUST). 

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  • Intervention Options to Accelerate Ecosystem Recovery From Coastal Eutrophication

    Duarte, Carlos M.; Krause-Jensen, Dorte (Frontiers Media SA, 2018-12-11)
    Three decades following the onset of efforts to revert widespread eutrophication of coastal ecosystems, evidence of improvement of ecosystem status is growing. However, cumulative pressures have developed in parallel to eutrophication, including those associated with climate change, such as warming, deoxygenation, ocean acidification and increased runoff. These additional pressures risk countering efforts to mitigate eutrophication and arrest coastal ecosystems in a state of eutrophication despite the efforts and significant resources already invested to revert coastal eutrophication. Here we argue that the time has arrived for a broader, more comprehensive approach to intervening to control eutrophication. Options for interventions include multiple levers controlling major pathways of nutrient budgets of coastal ecosystems, i.e., nutrient inputs, which is the intervention most commonly deployed, nutrient export, sequestration in sediments, and emissions of nitrogen to the atmosphere as N2 gas (denitrification). The levers involve local-scale hydrological engineering to increase flushing and nutrient export from (semi)enclosed coastal systems, ecological engineering such as sustainable aquaculture of seaweeds and mussels to enhance nutrient export and restoration of benthic habitats to increase sequestration in sediments as well as denitrification, and geo-engineering approaches including, with much precaution, aluminum injections in sediments. These proposed supplementary management levers to reduce eutrophication involve ecosystem-scale intervention and should be complemented with policy actions to protect benthic ecosystem components.Three decades following the onset of efforts to revert widespread eutrophication of coastal ecosystems, evidence of improvement of ecosystem status is growing. However, cumulative pressures have developed in parallel to eutrophication, including those associated with climate change, such as warming, deoxygenation, ocean acidification and increased runoff. These additional pressures risk countering efforts to mitigate eutrophication and arrest coastal ecosystems in a state of eutrophication despite the efforts and significant resources already invested to revert coastal eutrophication. Here we argue that the time has arrived for a broader, more comprehensive approach to intervening to control eutrophication. Options for interventions include multiple levers controlling major pathways of nutrient budgets of coastal ecosystems, i.e., nutrient inputs, which is the intervention most commonly deployed, nutrient export, sequestration in sediments, and emissions of nitrogen to the atmosphere as N2 gas (denitrification). The levers involve local-scale hydrological engineering to increase flushing and nutrient export from (semi)enclosed coastal systems, ecological engineering such as sustainable aquaculture of seaweeds and mussels to enhance nutrient export and restoration of benthic habitats to increase sequestration in sediments as well as denitrification, and geo-engineering approaches including, with much precaution, aluminum injections in sediments. These proposed supplementary management levers to reduce eutrophication involve ecosystem-scale intervention and should be complemented with policy actions to protect benthic ecosystem components.
  • Phylogenetically diverse endophytic bacteria from desert plants induce transcriptional changes of tissue-specific ion transporters and salinity stress in Arabidopsis thaliana

    Eida, Abdul Aziz; Alzubaidy, Hanin S.; Zélicourt, Axel de; Synek, Lukas; Alsharif, Wiam; Lafi, Feras Fawzi; Hirt, Heribert; Saad, Maged (Elsevier BV, 2018-12-07)
    Salinity severely hampers crop productivity worldwide and plant growth promoting bacteria could serve as a sustainable solution to improve plant growth under salt stress. However, the molecular mechanisms underlying salt stress tolerance promotion by beneficial bacteria remain unclear. In this work, six bacterial isolates from four different desert plant species were screened for their biochemical plant growth promoting traits and salinity stress tolerance promotion of the unknown host plant Arabidopsis thaliana. Five of the isolates induced variable root phenotypes but could all increase plant shoot and root weight under salinity stress. Inoculation of Arabidopsis with five isolates under salinity stress resulted in tissue-specific transcriptional changes of ion transporters and reduced Na+/K+ shoot ratios. The work provides first insights into the possible mechanisms and the commonality by which phylogenetically diverse bacteria from different desert plants induce salinity stress tolerance in Arabidopsis. The bacterial isolates provide new tools for studying abiotic stress tolerance mechanisms in plants and a promising agricultural solution for increasing crop yields in semi-arid regions.
  • Divergence between bread wheat and Triticum militinae in the powdery mildew resistance QPm.tut-4A locus and its implications for cloning of the resistance gene

    Janáková, Eva; Jakobson, Irena; Peusha, Hilma; Abrouk, Michael; Škopová, Monika; Šimková, Hana; Šafář, Jan; Vrána, Jan; Doležel, Jaroslav; Järve, Kadri; Valárik, Miroslav (Springer Nature, 2018-12-07)
    A segment of Triticum militinae chromosome 7G harbors a gene(s) conferring powdery mildew resistance which is effective at both the seedling and the adult plant stages when transferred into bread wheat (T. aestivum). The introgressed segment replaces a piece of wheat chromosome arm 4AL. An analysis of segregating materials generated to positionally clone the gene highlighted that in a plant heterozygous for the introgression segment, only limited recombination occurs between the introgressed region and bread wheat 4A. Nevertheless, 75 genetic markers were successfully placed within the region, thereby confining the gene to a 0.012 cM window along the 4AL arm. In a background lacking the Ph1 locus, the localized rate of recombination was raised 33-fold, enabling the reduction in the length of the region containing the resistance gene to a 480 kbp stretch harboring 12 predicted genes. The substituted segment in the reference sequence of bread wheat cv. Chinese Spring is longer (640 kbp) and harbors 16 genes. A comparison of the segments’ sequences revealed a high degree of divergence with respect to both their gene content and nucleotide sequence. Of the 12 T. militinae genes, only four have a homolog in cv. Chinese Spring. Possible candidate genes for the resistance have been identified based on function predicted from their sequence.
  • Fabrication of Self-Entangled 3-D Carbon Nanotube Networks from Metal-Organic Frameworks for Li-Ion Batteries

    Wang, Xinbo; Yin, Hang; Sheng, Guan; Wang, Wenxi; Zhang, Xixiang; Lai, Zhiping (American Chemical Society (ACS), 2018-12-07)
    Three-dimensional (3D) carbon nanomaterial assemblies are of great interest in emerging applications including electronic devices and energy storage because of their extraordinary high electrical conductivity, mechanical and thermal properties. However, the existing synthetic procedures of these materials are quite complex and energy-intensive. Herein, a facile approach is developed for fabricating a self-entangled carbon nanotube (CNT) network under convenient conditions (400 ℃ for 1 hour), breaking the critical limitations of the current available methods. The keys of forming such 3D CNT network are the fragmentation of the sacrificial MOFs into nano-sized particles, the reduction of metal elements in MOFs to highly active nanocatalysts by introducing hydrogen, and the supplement of external carbon source by introducing ethyne. In addition, the highly conductive 3D porous CNT network facilitates electron transfer and provides an excellent platform for high-performance Li-ion batteries (LIB).
  • Fabrication of Silicon Hierarchical Structures for Solar Cell Applications

    Wang, Hsin-Ping; Dharmaraj, Periyanagounder; Li, An-Cheng; He, Jr-Hau (Institute of Electrical and Electronics Engineers (IEEE), 2018-12-07)
    Hierarchical silicon structures consisting of micropyramids and nanowire arrays are fabricated by two-step chemical etching processes aimed at achieving cost and time effectiveness constraints without using any expensive vacuum system or complicated lithography process. The hierarchical structures can suppress the average reflectance to as low as 4.3% from 300 to 1100 nm without causing poor minority carrier lifetimes, exhibiting excellent broadband light-harvesting abilities with minimal recombination losses, which is the key point to design high performance nanostructured solar cells. By utilizing hierarchical structures in practical solar cells application, the short-circuit current density (JSC) shows a significant enhancement from 21.5 to 28.7 mA/cm2, and the conversion efficiency is enhanced by a factor of 35%. Such a significant enhancement is attributed not only to the superior light harvesting achieved by hierarchical structures but also to the benefit of small electrical losses in the solar cells. Thus, the concept and technique presented in this study open avenues for developing high-performance structure solar devices.

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