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  • Other Sources  (1,308)
  • Elsevier  (1,308)
  • 2015-2019  (1,308)
  • 1
    Publication Date: 2020-01-02
    Description: Fouling organisms in bivalve aquaculture cause significant economic losses for the industry. Husbandry strategies to reduce biofouling can involve avoidance, prevention, and treatment. In this way, the type of rope used to collect spat or grow bivalves may prevent or reduce fouling by particularly harmful species but remains largely untested. Further, while a range of eco-friendly control methods exist, their effect on widespread, common biofoulers is poorly known. We tested biofouling accumulation and spat collection for seven commercially used ropes, and evaluated treatments of ambient and heated seawater, acetic and citric acid, and combinations of both applied across a range of exposure times to two commercially grown shellfish (Mytilus galloprovincialis and Ostrea angasi) and three biofouling species (Ectopleura crocea, Ciona intestinalis and Styela clava). Rope types differed significantly in terms of fouling rates and spat collection, with specific rope types clearly advantageous, despite not being used commercially in our study area. Treatments proved variably successful, with E. crocea highly susceptible to all treatments, Ciona intestinalis moderately susceptible, and Styela clava relatively resistant. Excluding S. clava, efficacious treatments were attainable that did not adversely affect shellfish. Combining heat and acid treatments were more successful than individual treatments and provide a useful avenue for further trials. This study provides baseline evidence for treatment efficacy that will tailor longer-term, field trials to validate and streamline biofouling treatments in shellfish aquaculture.
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  • 2
    Publication Date: 2020-01-02
    Description: Sulfate-reducing bacteria (SRB) are a group of diverse anaerobic microorganisms omnipresent in natural habitats and engineered environments that use sulfur compounds as the electron acceptor for energy metabolism. Dissimilatory sulfate reduction (DSR)-based techniques mediated by SRB have been utilized in many sulfate-containing wastewater treatment systems worldwide, particularly for acid mine drainage, groundwater, sewage and industrial wastewater remediation. However, DSR processes are often operated suboptimally and disturbances are common in practical application. To improve the efficiency and robustness of SRB-based processes, it is necessary to study SRB metabolism and operational conditions. In this review, the mechanisms of DSR processes are reviewed and discussed focusing on intracellular and extracellular electron transfer with different electron donors (hydrogen, organics, methane and electrodes). Based on the understanding of the metabolism of SRB, responses of SRB to environmental stress (pH-, temperature-, and salinity-related stress) are summarized at the species and community levels. Application in these stressed conditions is discussed and future research is proposed. The feasibility of recovering energy and resources such as biohydrogen, hydrocarbons, polyhydroxyalkanoates, magnetite and metal sulfides through the use of SRB were investigated but some long-standing questions remain unanswered. Linking the existing scientific understanding and observations to practical application is the challenge as always for promotion of SRB-based techniques.
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  • 3
    Publication Date: 2020-01-02
    Description: Immune recognition of molecular patterns from microorganisms or self-altered cells activate effector responses that neutralize and eliminate these potentially harmful agents. In virtually every metazoan group the process is carried out by pattern recognition receptors, typically constituted by immunoglobulin (Ig), leucine rich repeat (LRR), and/or lectin domains. In order to get insights into the ancestral immune recognition repertoire of animals, we have sequenced the transcriptome of bacterially challenged colonies of the model cnidarian Hydractinia symbiolongicarpus using the Illumina platform. Over 116,000 assembled contigs were annotated by sequence similarity, domain architecture, and functionally. From these, a subset of 315 unique transcripts was predicted as the putative immune recognition repertoire of H. symbiolongicarpus. Interestingly, canonical Toll-like receptors (TLR) were not predicted, nor any transmembrane protein with the Toll/interleukine-1 receptor (TIR) domain. Yet, a variety of predicted proteins with transmembrane domains associated with LRR ectodomains were identified, as well as homologs of the key transduction factor NF-kB, and its associated regulatory proteins. This also has been documented in Hydra, and suggests that recognition and signaling initiation has been decoupled in the TLR system of hydrozoans. In contrast, both canonical and non-canonical NOD-like receptors were identified in H. symbiolongicarpus, showing a higher diversity than the TLR system and perhaps a wider functional landscape. The collection of Ig-like containing putative immune recognition molecules was diverse, and included at least 26 unique membrane-bound predicted proteins and 88 cytoplasmic/secreted predicted molecules. In addition, 25 and 5 transcripts encoding the Ig-like containing allorecognition determinants ALR1 and ALR2, respectively, were identified. Sequence and phylogenetic analyses suggested the presence of various transcriptionally active alr loci, and the action of recombination-based mechanisms diversifying them. Transcripts encoding at least six lectin families with putative roles in immune recognition were found, including 19 unique C-type lectins and 21 unique rhamnose-binding lectins. Other predicted immune recognition receptors included scavenger receptors from three families, lipopolysaccharide-binding proteins, cell-adhesion molecules and thioester-bond containing proteins. This analysis demonstrated that the putative immune recognition repertoire of H. symbiolongicarpus is large and diverse.
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  • 4
    Publication Date: 2020-01-02
    Description: We evaluated the relationship between interferon-induced transmembrane protein 1 (IFITM1) expression, epithelial–mesenchymal transition (EMT) signature and angiogenesis in lung adenocarcinoma. Additionally, we examined prognostic significance of IFITM1 according to pTNM stage to confirm that IFITM1 can serve as a complement to the pTNM stage. A total of 141 lung adenocarcinoma specimens were evaluated retrospectively by immunohistochemical staining for IFITM1, EMT markers (e-cadherin, β-catenin, and vimentin), and CD31 to measure microvessel density. IFITM1was expressed in 46.8% of the specimens. IFITM1 expression was significantly correlated with increased microvessel density (P = 0.048). However, IFITM1 expression was not associated with three EMT markers. In a multivariate analysis, IFITM1 was an independent prognostic factor for overall survival in a multivariate analysis (hazard ratio: 2.59, P = 0.01). Online database with data from 720 lung adenocarcinoma patients also revealed a negative prognostic significance of IFITM1 (P 〈 0.001). Furthermore, high IFITM1 expression was significantly correlated with decreased OS rates in each pTNM stage. IFITM1 is significantly correlated with angiogenesis and it may be used as a useful additional prognostic marker to aid pTNM classification.
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  • 5
    Publication Date: 2020-01-02
    Description: A first phytochemical investigation of apolar natural products of the seagrass Zostera marina L. (Zosteraceae) yielded cymodienol, a cyclic diarylheptanoid so far only known from the seagrass Cymodocea nodosa (Ucria) Asch. (Cymodoceaceae) and a previously undescribed diaryheptanoid, isotedearene A, which is closely related to tedarene A, a natural product previously described from the neotropic sponge Tedania ignis (Duchassaing & Michelotti, 1864) (Tedaniidae). Structures were established by mass spectrometry and extensive 1D and 2D NMR experiments.
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  • 6
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    Elsevier
    In:  Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 236 . p. 110524.
    Publication Date: 2020-08-04
    Description: Aquatic CO2 tensions may exceed 30–60 Torr (ca. 30,000–79,000 μatm, respectively; hypercarbia) in some environments inducing severe acid-base challenges in fish. Typically, during exposure to hypercarbia blood pH (pHe) is initially reduced and then compensated in association with an increase in plasma HCO3– in exchange for Cl−. Typically, intracellular pH (pHi) is reduced and recovery is to some degree coupled to pHe recovery (coupled pH regulation). However, during acute hypercarbia, pHe recovery has been proposed to be limited by an “apparent upper bicarbonate threshold”, restricting complete pHe recovery to below 15 Torr PCO2. At PCO2 values beyond that which fish can compensate pHe, some fish are able to fully protect pHi despite large sustained reductions in pHe (preferential pHi regulation) and can tolerate PCO2 〉 45 Torr. This review discusses pHe and pHi regulation during exposure to hypercarbia starting with modeling the capacity and theoretical limit to pHe compensation in 19 studies. Next, we discuss how fish compensate severe acute hypercarbia exposures beyond the putative limit of pHe compensation using preferential pHi regulation which has recently been observed to be common among fish subjected to severe hypercarbia. Finally, we consider the evolution of pH regulatory strategies in vertebrates, including how the presence of preferential pHi regulation in embryonic reptiles may indicate that it is an embryonic trait that is either lost or retained in adult vertebrates and may have served as an exaptation for key evolutionary transitions during vertebrate evolution.
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  • 7
    Publication Date: 2020-01-02
    Description: Interactions between microorganisms and clay minerals are ubiquitous in nature and are involved in the formation and transformation of clay minerals and the global cycles of many elements. The fungi/actinomyces in microbes are also associated with clay minerals, but bacteria are more widely linked. These interactions are also involved in the adsorption and fixation of heavy metals and the decomposition of organic pollutants in soil. Knowledge of these interactions can be utilised for the refinement and purification of clay minerals in industry. This review provides an overview of recent studies and obtains insights into the interactions between microorganisms and clay minerals. Microorganisms can induce the nucleation and growth of clay minerals. The metabolism of microorganisms can also degrade and transform clay minerals. The interaction between microorganisms and clay minerals promots the transformation of smectite to illite (S-I) and vice versa (I-S). Such interactions significantly contribute to the global cycles of various elements, such as Al, Si, Mg, Fe, P, S, C, and N. Microorganisms and clay minerals can form complexes and composite materials that adsorb heavy metals such as Cu, Cr, Cd, Pb, Zn, Co, Ni, Ag, and Hg. Microorganism adhesion to clay minerals is involved in the synergistic adsorption and decomposition of organic pollutants in soil and water. This literature review indicates that knowledge of the interactions between microorganisms and clay minerals has been significantly deepened over recent years. However, the interaction between microorganisms and clay minerals under natural geological conditions and the inherent mechanisms involved are not yet well understood. Future work on interactions between microorganisms and clay minerals has great implications for handling atmospheric micro/nano particle pollutants, understanding the formation, alteration and diagenesis of clay minerals and other related minerals, tracking primitive life on Earth and exploring extraterrestrial planets.
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  • 8
    Publication Date: 2020-01-02
    Description: Ribosomally synthesized and post-translationally modified peptides (RiPPs) are an important class of natural products that contain antibiotics and a variety of other bioactive compounds. The existing methods for discovery of RiPPs by combining genome mining and computational mass spectrometry are limited to discovering specific classes of RiPPs from small datasets, and these methods fail to handle unknown post-translational modifications. Here, we present MetaMiner, a software tool for addressing these challenges that is compatible with large-scale screening platforms for natural product discovery. After searching millions of spectra in the Global Natural Products Social (GNPS) molecular networking infrastructure against just eight genomic and metagenomic datasets, MetaMiner discovered 31 known and seven unknown RiPPs from diverse microbial communities, including human microbiome and lichen microbiome, and microorganisms isolated from the International Space Station.
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  • 9
    Publication Date: 2020-01-02
    Description: Disinfection byproducts (DBPs) are generated by disinfectants reacting with organic matters. Previous studies have focused on DBPs in drinking water, but they have not paid sufficient attention to DBPs in sewage treatment plants (STPs), where the sources and compositions of DBPs are much more complicated, and there is a likelihood of more toxic DBPs being formed. In this study, the occurrence of DBPs in six STPs in Hong Kong and the potential impact of the effluents from the STPs on the marine environment were investigated. In STPs, the mean concentrations of the total DBPs ranged from 1160 to 17,019 ng/L, 1562 to 20,795 ng/L, and 289 to 1037 ng/L in the influent, effluent, and seawater, respectively. Trihalomethanes, haloacetonitriles, and trihalophenols were the most commonly detected DBPs, whereas hexachloro-1,3-butadiene and halocarbazoles were not detected in the STPs and in the marine environment in Hong Kong. Secondary treatment efficiently removed DBPs and DBP precursors. Regarding disinfection techniques, UV irradiation showed little effect on the concentrations of DBPs, whereas sodium hypochlorite significantly elevated the levels of both traditional and emerging DBPs. The effluents from two selected STPs that use chlorination have an obvious impact on the marine environment. This work presents the potential sources of DBPs in sewage, the influence of the treatment processes and disinfection techniques employed in STPs on the removal/formation of DBPs, and the impact of the effluents from the STPs on the marine environment. This work also highlights the need for investigating the emerging DBPs generated in STPs and their related environmental concerns.
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  • 10
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    Elsevier
    In:  Earth-Science Reviews, 196 (Article number 102889).
    Publication Date: 2020-01-17
    Description: The Las Cañadas caldera is one of the best exposed volcanic calderas in the world and one of the few known evolved alkaline volcanoes. It truncates the pre-Teide-Pico Viejo central volcanic edifice, the Las Cañadas edifice, which started to take shape at the end of the formation of a large basaltic shield that forms the main part of island of Tenerife. Historically, the origin of the Las Cañadas caldera has been controversial, as it has been interpreted as the result of either multiple vertical collapses or due to a giant sector collapse. The available stratigraphical, structural, volcanological, geochronological, and geophysical data, as well as its comparison to other well-known collapse calderas should not offer any doubt as to its direct relationship with a long history of phonolitic explosive volcanism. However, the existence of large landslide events on Tenerife, which have significantly modified the flanks of the Las Cañadas volcano, have also been used as a potential explanation for the origin of the Las Cañadas depression. This contribution reviews the available information on the Las Cañadas caldera, the causes of this controversy, and rationalises the most plausible explanation for the origin of Las Cañadas caldera based on the current evidence gathered from all previous studies.
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  • 11
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    Elsevier
    In:  Ocean Modelling, 137 . pp. 21-39.
    Publication Date: 2020-01-02
    Description: Oceanic fluxes through Fram Strait may significantly contribute to climate variations in the Arctic. However, their observations are difficult. Here, a 26-year numerical model simulation is used to derive oceanic proxies for interannual variability in heat fluxes through Fram Strait. It is found that variability in the cross-slope gradient of sea surface height (SSH) across the West Spitsbergen Current (WSC) can explain about 90% of the variance of winter and annual mean volume transports of Atlantic water at 79°N. Given the strong covariance between the simulated heat flux in the slope current along Svalbard and the corresponding volume transport, variability of the SSH gradient across the WSC is also found to account for about 80% of the variance of heat flux associated with the northward flow through Fram Strait. Moreover, variations in the SSH gradient across the Arctic Slope Current (ASC) northeast of Svalbard at 31°E explain about 85% of the variance of heat flux there and about 80% of the variance of the net heat flux upstream through Fram Strait. Finally, about 85% and 75% of the variance of the net heat flux through Fram Strait is associated with anomalies of the eastward volume transport and depth-averaged core velocity in the ASC, respectively. These relations indicate that monitoring of the flow in the ASC, even with a single current meter mooring, or of the SSH gradient across this current derived from either in situ or remote measurements may provide useful proxies for the heat import to the Arctic Ocean.
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  • 12
    Publication Date: 2020-01-02
    Description: Hydrate dissociation equilibrium conditions for the mixture of carbon dioxide (CO2), nitrogen (N2), and water (H2O) are measured in the temperature range of 274.15–280.15 K. The relative molar composition of carbon dioxide in the feed gas mixture varies between 0.05 and 0.25 which is the interesting range of composition when it comes to production of methane, and sequestration of carbon dioxide, from methane hydrate reservoirs. A thermodynamic model is presented based on the classical van der Waals and Platteeuw (vdW-P) solid solution theory for the hydrate phase combined with the Equation of State (EoS) for combustion gas and combustion gas-like mixtures (CG-EoS). The results of this model are compared to the dissociation data measured here, along with all available data from the experimental literature. The predicted results from two thermodynamic software programs, CSMGem, and Multiflash (which use Peng-Robinson (PR) and Cubic Plus Association (CPA) EoSs respectively), are also statistically evaluated. A Clausius-Clapeyron type equation was used to derive the enthalpy of dissociation at 279.15 K, and the values were found to converge for mixtures containing 0.1–0.25 mol fraction of carbon dioxide.
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  • 13
    Publication Date: 2020-01-02
    Description: Highlights • Volcanological evidences were useful for modelling the slope movements of Stromboli. • Subvertical dyke intrusion affects only local stability of the dry subaerial slope. • Larger instabilities can be triggered only by dyke intrusion with relevant horizontal component. • Static liquefaction due to grain crushing can explain the submarine slide. • Submarine sliding can propagate backwards and influence the subaerial sector. Abstract The aim of the paper is to provide quantitative elements on the mechanisms that controlled the slope instabilities occurred after two major recent eruptions at Stromboli volcano (i.e. 2002–2003 and 2007). After a brief description of the geological setting and of the largest well documented instability phenomena on volcano flanks, the main objective is pursued using three-dimensional stress-strain analyses for modelling the effects of the magma intrusion on the stability of the volcano flank. Modelling is based on the results of an extensive geotechnical characterization of the volcaniclastic and lava materials. The numerical analyses investigate the influence of different paths and geometry of magma intrusion as well as the spatial variation of mechanical properties. As a result, favourable conditions for specific failure modes are identified. The stress-strain analyses show that magma intrusion can cause both a local failure of a wedge immediately downslope from the dyke or deep-seated movement involving large part of the slope; these two mechanisms were consistent with the deformative patterns observed during the 2007 and 2002–2003 eruptions, respectively. The magma thrust induces shear strains up to levels associated to appreciable grain crushing even below the sea level, where flow liquefaction can be invoked to explain the occurrence of past submarine slides. The submarine landslide is analysed by a combined finite element – limit equilibrium approach that demonstrates that instability conditions can develop if the loading exerted by the upper portion of the slope is sufficiently fast to produce undrained conditions. The analyses also support the hypothesis that at the 2002 subaerial failure occurred, due to combined effects of a magma mild thrust and the removal of the toe support caused by the preceding submarine slide.
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  • 14
    Publication Date: 2020-01-02
    Description: A probabilistic hazard analysis of tsunami generated by subaqueous volcanic explosion is applied to the Campi Flegrei caldera (Campania, Italy). An event tree is developed to quantify the tsunami hazard due to the submarine explosions by: i) defining potential size classes of explosion magnitude on the basis of past volcanic activity in the Campi Flegrei caldera and sites in the underwater part of the caldera; ii) simulating the generation and propagation of the consequent tsunami waves able to reach the coasts of the Campania region for all combinations of tsunami-generating vents and sizes; and iii) quantifying the tsunami probability and relative uncertainty, conditional upon the occurrence of an underwater eruption at Campi Flegrei. Tsunami hazard generated by subaqueous volcanic explosions is considered crucial because of its potential high impact on the densely populated coastal areas of the Pozzuoli Bay and Gulf of Naples even if the probability for eruptions in the submarine part of the caldera is certainly low. The tsunami hazard analysis is presented using conditional hazard curves and maps, that is calculating the probability (and relative uncertainties) of exceeding given tsunami intensity thresholds (wave amplitudes at the coast), given the occurrence of a subaqueous eruption. The results indicate that a significant tsunami hazard exists in many areas of the Bay of Naples.
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  • 15
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    Elsevier
    In:  Trends in Immunology . pp. 1-13.
    Publication Date: 2020-01-02
    Description: Neutrophils promptly accumulate in large numbers at sites of tissue injury. Injuries to the skin or mucosae disrupt barriers against the external environment, and the bactericidal actions of neutrophils are important in preventing microbial invasion. Neutrophils have also been associated with exacerbated inflammation, for example in non-healing wounds or in conditions such as inflammatory bowel disease (IBD). However, additional neutrophil functions important for angiogenesis and tissue restoration have been uncovered in models of sterile and ischemic injury, as well as in tumors. These functions are also relevant in healing skin and mucosal wounds, and can be impaired in conditions associated with non-healing wounds, such as diabetes. Here, we discuss our current understanding of neutrophil contributions to healing, and how the latter can be compromised in disease.
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  • 16
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    Elsevier
    In:  Cell Calcium, 80 . pp. 38-45.
    Publication Date: 2020-01-02
    Description: Alterations in the (bio)chemical and physical microenvironment of cells accompany and often promote disease formation and progression. This is particularly well established for solid cancers, which are typically stiffer than the healthy tissue in which they arise, and often display profound acidification of their interstitial fluid. Cell surface receptors can sense changes in the mechanical and (bio)chemical properties of the surrounding extracellular matrix and fluid, and signalling through these receptors is thought to play a key role in disease development and advancement. This review will look at ion channels and G protein coupled receptors that are activated by mechanical cues and extracellular acidosis, and stimulation of which results in increases in intracellular Ca2+ concentrations. Cellular Ca2+ levels are dysregulated in cancer as well as cancer-associated cells, and mechano- and proton-sensing proteins likely contribute to these aberrant intracellular Ca2+ signals, making them attractive targets for therapeutic intervention.
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  • 17
    Publication Date: 2020-01-02
    Description: Adhesive ascidians have caused serious biofouling problems and huge economic losses in marine ecosystems. However, adhesion mechanisms, particularly on functional proteins involved in ascidian adhesion, remain largely unexplored. Here, we identified 26 representative stolon proteins from the highly invasive fouling ascidian Ciona robusta using the proteomics approach. The uncharacterized stolon proteins were rich in adhesion-related conserved domains. Real-time quantitative PCR further revealed specific expressions of these uncharacterized protein genes in stolon tissue, suggesting their potential roles in stolon adhesion.〉 A recombinant vWFA domain-containing uncharacterized protein, ascidian stolon protein 1 (ASP-1), was successfully expressed in a baculovirus-insect cell system and purified in vitro. Coating experiment showed that tyrosinase-modified ASP-1 could absorb to glass and organic glass stronger than unmodified ASP-1, while only modified ASP-1 could absorb to aluminum foil. Quartz crystal microbalance analysis also showed the increase in absorption ability of ASP-1 after modification. In addition, abundant 3,4-l-dihydroxyphenylalanine (DOPA) in modified protein was detected by nitroblue tetrazolium staining. These results suggest that ASP-1 be involved in ascidian DOPA-dependent and material-selective adhesion. Overall, this study provides insight into molecular mechanisms of C. robusta stolon adhesion, and findings here are expected to be conductive to develop strategies against biofouling caused by ascidians.
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  • 18
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    Elsevier
    In:  International Journal of Rock Mechanics and Mining Sciences, 114 . pp. 164-174.
    Publication Date: 2020-01-02
    Description: This study explores the steady-state propagation of hydraulic fractures in ductile and elastic media, with anemphasis on time-varying fracture geometry. A series of well-controlled experiments was performed, in whichthe hydraulic fracture propagation behaviors in two-dimensionally confined gelatin plates were monitored whilevarying the gelatin stiffness, fracturingfluid viscosity, and injectionflow rate. In all cases, comet-shaped, bi-wingfractures were initiated, and thefluid pressure responses and fracture geometry, including propagation velocity,length, width, and opening area were analyzed using the acquired time-lapsed images. The fracture propagationinitiated before the peak pressure value, and the initiation pressure increased with the gelatin stiffness, injectionflow rate, and viscosity, however, mainly governed by the elastic stiffness. Contrary to theoretical models, twostates were identified over the course of comet-shaped hydraulic fracture propagation: a transient state in whichthe fracture propagation velocity and fracture width gradually increased, and thereafter, a steady state where thevelocity and width became consistent. As a result, the steady-state propagation velocity was primarily de-termined by theflow rate, and the fracture width in a steady state was proportional to thefluid pressure nor-malized by the medium stiffness, owing to the elastic response. Based on experimental observations, simple butrobust semi-empirical models were suggested to predict the fracture width and propagation velocity in a steadystate.
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  • 19
    Publication Date: 2020-01-02
    Description: Ascidians are marine invertebrates closely related to vertebrates. These animals have been studied to address complex processes, including evolution of the immune system and developmental biology. As holobionts, housing millions of bacteria in a close relationship that drives adaptive fitness to environmental conditions, ascidians are successful invaders and dominant components of the benthic communities. Further, tunicates and their associated microbiota are recognized as producers of chemical structures with pharmacological potential, and over 1000 such molecules have been described so far. This review covers aspects of ascidian biology that make them promising model organisms in various fields and important for drug discovery.
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  • 20
    Publication Date: 2021-01-08
    Description: Humic substances (humics) are ubiquitous in terrestrial and aquatic environments where they can serve as electron acceptors for anaerobic oxidation of organic compounds. Methane is a powerful greenhouse gas, as well as the least reactive organic molecule. Anaerobic oxidation of methane (AOM) coupled to microbial reduction of various electron acceptors plays a crucial role in mitigating methane emissions. Here, we reported that humics could serve as terminal electron acceptors for AOM using enriched nitrate-reducing AOM microorganisms. AOM coupled to the reduction of humics was demonstrated based on the production of 13C-labelled carbon dioxide, and AOM activity was evaluated with different methane partial pressures and electron acceptor concentrations. After three-cycle reduction, both AOM activity and copy numbers of the archaea 16S rRNA and mcrA genes were the highest when anthraquinone-2,6-disulfonic acid and anthraquinone-2-sulfonic acid were electron acceptors. The high-throughput sequencing results suggested that ANME-2d were the dominant methane oxidation archaea after humics reduction, although the partner bacteria NC10 trended downward, other reported humics reduction bacteria (Geobactor and Anammox) appeared. The potential electron transfer models from ANME-2d to humics were proposed. These results enable a better understanding of available electron acceptors for AOM in natural environments and broaden our insight into the significant role of ANME-2d.
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  • 21
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    Elsevier
    In:  Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1866 (4). pp. 699-712.
    Publication Date: 2020-01-02
    Description: The prevailing models of stress induced Programmed Cell Death (PCD) posit that excess extracellular chemicals interact with or enter cells and disrupts cellular homeostasis. This activates signalling cascades involving the mitochondria, an increase in the steady state levels of Reactive Oxygen Species (ROS) as well as the activation of Bax and caspases. Further, the increased ROS also causes cellular damage that triggers or enhances PCD responses. The models have been modified in a number of ways, for example to include the existence of caspase and Bax independent forms of PCD. More recently, the ubiquity of ROS has also been challenged in part based on the failure of anti-oxidants to protect from diseases with increased intensity of oxidative stress. Here we focus on a number of other, often overlooked, observations regarding stress mediated responses that may further increase our mechanistic understanding of PCD. These include the concept of the “milieu intérieur” which suggests that cells actively protect themselves (adaptive homeostasis) in part by limiting entry to most extracellular chemicals. Of similar importance, stress also increases the levels of other stress inducible second messengers including ceramide, iron and calcium. This review focuses on the concept that stress is an agonist that conveys information that is transduced into the cell to activate the appropriate genetically encoded cell death and survival responses.
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  • 22
    Publication Date: 2020-01-02
    Description: The U.N. Framework Convention on Climate Change’s (UNFCCC’s) Paris Agreement—which aims to limit climate change and increase global resilience to its effects—was a breakthrough in climate diplomacy, committing its Parties to develop and update national climate plans. Yet the Parties to the Agreement have largely overlooked the effect of climate change on ocean-based communities, economies, and ecosystems—as well as the role that the ocean can play in mitigating and adapting to climate change. Because the ocean is an integral part of the climate system, stronger inclusion of ocean issues is critical to achieving the Agreement’s goals. Here we discuss four ocean-climate linkages that suggest specific responses by Parties to the Agreement connected to 1) accelerating climate ambition, including via sustainable ocean-based mitigation strategies; 2) focusing on CO2 emissions to address ocean acidification; 3) better understanding ocean-based mitigation; and 4) pursuing ocean-based adaptation. These linkages offer a more complete perspective on the reasons strong climate action is necessary and inform a systematic approach for addressing ocean issues under the Agreement to strengthen climate mitigation and adaptation.
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  • 23
    Publication Date: 2020-01-02
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  • 24
    Publication Date: 2020-01-02
    Description: Shallow coral reefs provide food, income, well-being and coastal protection to countries around the Indian Ocean and Asia. These reefs are under threat due to many anthropogenic stressors including pollution, sedimentation, overfishing, sea surface warming and habitat destruction. Ocean acidification interacts with these factors to exacerbate stress on coral reefs. Effective solutions in tackling the impact of ocean acidification require a thorough understanding of the current adaptive capacity of each nation to deal with the consequences. Here, we aim to help the decision-making process for policy makers in dealing with these future challenges at the regional and national levels. We recommend that a series of evaluations be made to understand the current status of each nation in this region in dealing with ocean acidification impacts by assessing the climate policy, education, policy coherence, related research activities, adaptive capacity of reef-dependent economic sectors and local management. Indonesia and Thailand, are selected as case studies. We also highlight general recommendations on mitigation and adaptation to ocean acidification impacts on coral reefs and propose well-designed research program would be necessary for developing a more targeted policy agenda in this region.
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  • 25
    Publication Date: 2020-01-02
    Description: Highlights • Hydrodynamic modelling is a useful tool to understand the formation of contourites. • Contourite drifts develop in zones of minimum bottom currents. • Plastered drifts develop in a zone of weak currents between two zones of stronger currents. • High intensity events control the formation of erosional features as moats. • Gyres favour the formation of contourites along starved margins in confined basins. Abstract Contourites are common morphological features along continental margins where currents encounter the seafloor. They can provide long-term archives of palaeoceanography, may be prone to sediment instability, and can have a great potential for hydrocarbon exploration. Despite their importance and increasingly recognised ubiquitous occurrence worldwide, the link between oceanographic processes and contourite features is poorly constrained. In particular, it is unclear under which specific conditions sediments are mobilised, modified and deposited by bottom currents. Here, we aim to determine key bottom current characteristics (velocity and bottom shear stress) affecting contourite deposition, by assuming that recent oceanographic regimes may be extended back in time over the past glacial-interglacial cycles, with strong winter circulation assumed similar to glacial conditions and weak summer circulation to interglacials. We present an integrated study from the NW Mediterranean Sea that couples results of the MARS3D hydrodynamic model with high-resolution sedimentological and geophysical data (piston cores, multibeam bathymetry and high resolution seismic data). Near bottom circulation was modelled during winter and summer 2013 as representative of past periods of high and low current intensity, respectively. Model results match well with the extent of contourite depositional systems and their different localised morphologic elements. We deduce that higher intensity events control the formation of erosional features such as moats and abraded surfaces. The heterogeneous distribution of bottom-current intensity on slopes explains the development of different types of contourite drifts. Plastered drifts form in zones of low bottom-current velocities constrained upslope and downslope by higher current velocities. Separated elongated mounded drifts develop where fast bottom-currents decelerate at foot of the slope. In contrast, no mounded contourite morphologies develop when the current velocity is homogeneous across the slope, especially in margins prone to downslope sediment transport processes. In confined basins, gyres may transport sediment in suspension from a margin with a high sediment supply to an adjacent starved margin, favouring the development of fine-grained contourites in the latter. Our results provide new insights into how detailed bottom-circulation modelling and seafloor geomorphological analyses can improve the understanding of palaeoflow-regimes, at least over time spans when the overall paleogeography and the distribution of contourite drifts is comparable to present-day conditions. The approach of coupled hydrodynamic models and geomorphological interpretations proposed here for depositional, erosional and mixed contourite features may be used to understand other areas affected by bottom currents, and for a better conceptual understanding of bottom-current processes and their interactions with the seafloor.
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  • 26
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    Elsevier
    In:  In: Intracellular Signalling Proteins. , ed. by Donev, R. Advances in protein chemistry and structural biology, 116 . Elsevier, Cambridge, pp. 421-449. ISBN 978-0-12-815561-5
    Publication Date: 2019-05-27
    Description: Cell-to-cell signaling is responsible for regulation of many developmental processes such as proliferation, cell migration, survival, cell fate specification and axis patterning. In this article we discussed the role of signaling in the metamorphosis of sponges with a focus on epithelial–mesenchymal transition (EMT) accompanying this event. Sponges (Porifera) are an ancient lineage of morphologically simple animals occupying a basal position on the tree of life. The study of these animals is necessary for understanding the origin of multicellularity and the evolution of developmental processes. Development of sponges is quite diverse. It finishes with the metamorphosis of a free-swimming larva into a young settled sponge. The outer surface of sponge larvae consists of a ciliated epithelial sheath, which ensures locomotion, while their internal structure varies from genus to genus. The fate of larval ciliated cells is the most intriguing aspect of metamorphosis. In this review we discuss the fate of larval ciliated cells, the processes going on in cells during metamorphosis at the molecular level and the regulation of this process. The review is based on information about several sponge species with a focus on Halisarca dujardini, Sycon ciliatum and Amphimedon queenslandica. In our model sponge, H. dujardini, ciliated cells leave the larval epithelium during metamorphosis and migrate to the internal cell mass as amoeboid cells to be differentiated into choanocytes of the juvenile sponge. Ciliated cells undergo EMT and internalize within minutes. As EMT involves the disappearance of adherens junctions and as cadherin, the main adherens junction protein, was identified in the transcriptome of several sponges, we suppose that EMT is regulated through cadherin-containing adherens junctions between ciliated cells. We failed to identify the master genes of EMT in the H. dujardini transcriptome, possibly because transcription was absent in the sequenced stages. They may be revealed by a search in the genome. The master genes themselves are controlled by various signaling pathways. Sponges have all the six signaling pathways conserved in Metazoa: Wnt, TGF-beta, Hedgehog, Notch, FGF and NO-dependent pathways. Summarizing the new data about intercellular communication in sponges, we can put forward two main questions regarding metamorphosis: (1) Which of the signaling pathways and in what hierarchical order are involved in metamorphosis? (2) How is the organization of a young sponge related to that of the larva or, in other words, is there a heredity of axes between the larva and the adult sponge?
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  • 27
    Publication Date: 2020-01-02
    Description: Background and aims: The extracellular calcium-binding protein family member thrombospondin-4 (THBS4) regulates cell migration, proliferation, attachment, adhesion, angiogenesis, neural development, tissue structure, organ development, pain signal transduction, and tumor growth. The aim of this study was to study THBS4 expression in hepatocellular carcinoma (HCC) and determine if it was a prognostic marker for this malignancy. Methods: We used immunohistochemistry and tissue microarrays to evaluate THBS4 expression in 84 HCC and matched para-cancerous tissues. Then, we assessed relationships between THBS4 expression and clinicopathological parameters. Results: THBS4 expression was higher in HCCs than in matched para-cancerous tissues (P 〈 0.001). There was a significant correlation between high THBS4 levels and preoperative serum alanine aminotransferase (P 〈 0.04). In HCC patients, high THBS4 expression was associated with shorter overall and disease-free survival compared with low THBS4 expression. Additionally, subgroup analysis showed that high THBS4 levels were only associated with poor overall survival for alpha-fetoprotein 〉40 ng/mL (P = 0.028) and cirrhosis (P = 0.002). Multivariate analysis showed that high THBS4 expression was an independent prognostic factor for both overall and disease-free survival. Conclusions: Our data suggest that THBS4 may play a role in HCC development, and thus may be an independent prognostic marker and/or potential therapeutic target for HCC patients.
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  • 28
    Publication Date: 2020-01-02
    Description: Highlights • Compilation of rifting events in the Neoproterozoic • Analysis of continental arc, continental rift and connectedness of continental lithosphere for the last 1 Ga • Two stage supercontinent cycle may better explain changes in the connectedness of continental lithosphere • Extraversion and introversion models of successive supercontinents occur on different timescales Abstract The extent of continental rifts and subduction zones through deep geological time provides insights into the mechanisms behind supercontinent cycles and the long term evolution of the mantle. However, previous compilations have stopped short of mapping the locations of rifts and subduction zones continuously since the Neoproterozoic and within a self-consistent plate kinematic framework. Using recently published plate models with continuously closing boundaries for the Neoproterozoic and Phanerozoic, we estimate how rift and peri-continental subduction length vary from 1 Ga to present and test hypotheses pertaining to the supercontinent cycle and supercontinent breakup. We extract measures of continental perimeter-to-area ratio as a proxy for the existence of a supercontinent, where during times of supercontinent existence the perimeter-to-area ratio should be low, and during assembly and dispersal it should be high. The amalgamation of Gondwana is clearly represented by changes in the length of peri-continental subduction and the breakup of Rodinia and Pangea by changes in rift lengths. The assembly of Pangea is not clearly defined using plate boundary lengths, likely because its formation resulted from the collision of only two large continents. Instead the assembly of Gondwana (ca. 520 Ma) marks the most prominent change in arc length and perimeter-to-area ratio during the last billion years suggesting that Gondwana during the Early Palaeozoic could explicitly be considered part of a Phanerozoic supercontinent. Consequently, the traditional understanding of the supercontinent cycle, in terms of supercontinent existence for short periods of time before dispersal and re-accretion, may be inadequate to fully describe the cycle. Instead, either a two-stage supercontinent cycle could be a more appropriate concept, or alternatively the time period of 1 to 0 Ga has to be considered as being dominated by supercontinent existence, with brief periods of dispersal and amalgamation.
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  • 29
    Publication Date: 2020-01-02
    Description: Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) present a viable alternative column system to conventional reinforced concrete for new construction. A CFFT system consists of two parts: the prefabricated FRP tube and the concrete core. The exterior shell provides longitudinal and transverse reinforcement for the concrete core. Many design variables of the FRP shell, including its thickness and winding angle, can be altered to achieve desirable confinement, axial capacity, and ductility in CFFT columns. This research proposes a methodology to determine the minimum fiber angle for filament wound FRP tubes to provide confinement to the concrete core in CFFTs. The proposed approach was used to calculate the threshold winding angle for glass FRPs, which was found to be ±51.5°. To evaluate the proposed fiber angle threshold, 11 circular specimens with a concrete core diameter of 152 mm, a height of 597 mm, and glass fibers at angles of ±45°, ±55°, or ±65° were tested under cyclic axial compression. The effect of fiber angle and thickness of the shell were studied. The experimental results show that the level of confinement increases with winding angle and number of layers of fiber reinforcing, and the specimens with wind angles below the threshold, i.e. ±45°, behave similarly to unconfined concrete.
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  • 30
    Publication Date: 2020-01-02
    Description: Seaweeds are an important component of human diets, especially in Asia and the Pacific islands, and have shown chemopreventive as well as anti-inflammatory properties. However, structural characterization and mechanistic insight of seaweed components responsible for their biological activities are lacking. We isolated cymopol and related natural products from the marine green alga Cymopolia barbata and demonstrated their function as activators of transcription factor Nrf2-mediated antioxidant response to increase the cellular antioxidant status. We probed the reactivity of the bioactivation product of cymopol, cymopol quinone, which was able to modify various cysteine residues of Nrf2's cytoplasmic repressor protein Keap1. The observed adducts are reflective of the polypharmacology at the level of natural product, due to multiple electrophilic centers, and at the amino acid level of the cysteine-rich target protein Keap1. The non-polar C. barbata extract and its major active component cymopol, reduced inflammatory gene transcription in vitro in macrophages and mouse embryonic fibroblasts in an Nrf2-dependent manner. Cymopol-containing extracts attenuated neutrophil migration in a zebrafish tail wound model. RNA-seq analysis of colonic tissues of mice exposed to non-polar extract or cymopol showed an antioxidant and anti-inflammatory response, with more pronounced effects exhibited by the extract. Cymopolia extract reduced DSS-induced colitis as measured by fecal lipocalin concentration. RNA-seq showed that mucosal-associated bacterial composition and transcriptional profile in large intestines were beneficially altered to varying degrees in mice treated with either the extract or cymopol. We conclude that seaweed-derived compounds, especially cymopol, alter Nrf2-mediated host and microbial gene expression, thereby providing polypharmacological effects.
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  • 31
    Publication Date: 2020-01-02
    Description: The phylum Cercozoa consists of a diverse assemblage of amoeboid and flagellated protists that forms a major component of the supergroup, Rhizaria. However, despite its size and ubiquity, the phylogeny of the Cercozoa remains unclear as morphological variability between cercozoan species and ambiguity in molecular analyses, including phylogenomic approaches, have produced ambiguous results and raised doubts about the monophyly of the group. Here we sought to resolve these ambiguities using a 161-gene phylogenetic dataset with data from newly available genomes and deeply sequenced transcriptomes, including three new transcriptomes from Aurigamonas solis, Abollifer prolabens, and a novel species, Lapot gusevi n. gen. n. sp. Our phylogenomic analysis strongly supported a monophyletic Cercozoa, and approximately-unbiased tests rejected the paraphyletic topologies observed in previous studies. The transcriptome of L. gusevi represents the first transcriptomic data from the large and recently characterized Aquavolonidae-Treumulida-'Novel Clade 12' group, and phylogenomics supported its position as sister to the cercozoan subphylum, Endomyxa. These results provide insights into the phylogeny of the Cercozoa and the Rhizaria as a whole.
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  • 32
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    Elsevier
    In:  Journal of Volcanology and Geothermal Research, 388 (Article number 106686).
    Publication Date: 2021-01-08
    Description: The target of this study is the Fogo Island in Cape Verde, where the hazards (caldera and/or flank collapse) and the timing (120 ka or younger?) are still controversial. Using high-resolution DEM, field geological and structural analysis, and high-precision K-Ar dating, we produced an age-calibrated volcanic stratigraphy of Fogo’s summit (Chã das Caldeiras, for the last ca. 220 ka). From this, we infer the following evolution and associated processes: (1) the Fogo Volcano formed during seven stages of construction and partial destruction; (2) three flank collapses can be recognised, the biggest of which occurred between 60 and 43 ka; (3) this collapse occurred retrogressively, producing at least two distinct collapse blocks; (4) the innermost collapse was only partial, forming a flat step where a new volcano (Pico do Fogo) grew and formed the Chã das Caldeiras (literally Flat of the Calderas); (5) the removal of the buttressing eastern flank by the outermost collapse can be responsible for the seemingly “caldera” structure; (6) the growing load of the young volcano can produce a new flank failure following the innermost fault; (7) the young and closely spaced collapse ages here reported indicate a significant risk for the inhabitants of Fogo, in particular, and for the whole Cape Verde archipelago (and Atlantic seaboard) if a tsunami is produced by a future catastrophic flank collapse.
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  • 33
    Publication Date: 2020-01-02
    Description: Objectively determining the level of ecosystem model complexity necessary to achieve meaningful representations of biogeochemical cycles at different spatial and temporal scales is an outstanding issue in marine ecosystem modeling.As part of the development of a three-dimensional (3D) Regional Ocean Modelling System (ROMS) application for the northwest North Atlantic Ocean, we compare model results from three alternative ecosystem model versions in which ecological complexity was increased in a step-wise fashion. In order to ensure an objective comparison, the models were optimized to replicate observations of satellite surface chlorophyll, and in situ chlorophyll and nitrate profiles. To overcome the high computational cost of optimizing 3D models, we use a surrogate-based optimization method; that is, an ensemble of one-dimensional (1D) models is used as a proxy of the ecosystem model behavior in the 3D setting. The 1D models were configured at locations where in situ profiles are available. A total of 17 optimization experiments aim to evaluate different aspects of the comparison between the ecosystem models. We show that for all ecosystem model versions the optimized model performance degrades when the optimization includes all observed variables at all locations instead of individual locations only. Moreover, the choice of parameters to be optimized can significantly affect the behavior of the optimized models and is most noticeable when multiple phytoplankton and zooplankton groups are included. Additionally, evaluation of spatial patterns in optimal parameter values at individual locations allows us to assess geographical model portability. In general, an optimized complex model can achieve lower model-data misfits against assimilated data than simple models, but is also more prone to generating unintended trophic relations. The more complex model also had decreased performance when applied to locations different than those used for calibration (i.e., “portability experiments”), which is discussed in the context of the design of the cost function and selection of parameters to optimize.
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  • 34
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    Elsevier
    In:  In: Seafloor processes. , ed. by Cochran, J. K., Bokuniewicz, H. J. and Yager, P. L. Encyclopedia of Ocean Sciences, 4 . Elsevier, San Diego, pp. 192-200. ISBN 978-0-12-813082-7
    Publication Date: 2019-10-09
    Description: The particle flux, often termed the biological pump, plays a central role in biogeochemical cycles of carbon and many elements, provides the main food source for life in the ocean interior and controls, in part, ocean uptake of atmospheric carbon dioxide and spatial patterns of ocean productivity. The flux of particles through the water column represents a dynamic balance between processes that generate large sinking particles within the surface photic zone, the export of this material out of the surface zone, and particle cycling processes that consume, modify and produce new sinking particles within the ocean's interior.
    Type: Book chapter , NonPeerReviewed
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  • 35
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 510 . pp. 54-63.
    Publication Date: 2020-01-02
    Description: Seagrass meadows ecosystem engineering effects are correlated to their density (which is in turn linked to seasonal cycles) and often cannot be perceived below a given threshold level of engineer density. The density and biomass of seagrass meadows (Z. marina) together with associated macrophytes undergo substantial seasonal changes, with clear declines in winter. The present study aims to test whether the seasonal changes in the density of recovering seagrass meadows affect the benthic food webs of the southern Baltic Sea (Puck Bay). It includes meiofauna, macrofauna and fish of vegetated and unvegetated habitats in summer and winter seasons. Two levels of organization have been tested – species-specific diet preferences using stable isotopes (δ13C, δ15N) in Bayesian mixing models (MixSIAR) and the community-scale food web characteristics by means of isotopic niches (SIBER). Between-habitat differences were observed for grazers, as a greater food source diversity in species from vegetated habitats was noted in both seasons. Larger between-habitat differences in winter were documented for suspension/detritus feeders. The community-wide approach showed that the differences between the habitats were greater in winter than in summer (as indicated by the lower overlap of the respective isotope niches). Overall, the presence of seagrass meadows increased ecological stability (in terms of the range of food sources utilized by consumers) in the faunal assemblage, while invertebrates from unvegetated areas shifted their diet to cope with winter conditions. Therefore, as a more complex system, not sensitive to seasonal changes, Z. marina meadows create a stable habitat with high resilience potential.
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  • 36
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    Elsevier
    In:  Journal of Computer Languages, 52 . pp. 44-54.
    Publication Date: 2020-01-17
    Description: Business Intelligence applications often handle data sets that contain uncertain values. In this contribution, we focus on product costing, which deals with the average costs of product components – that vary significantly based on many factors such as inflation, exchange rates, and commodity prices. After experts estimate the uncertainty information for single items, decision makers need to quickly ascertain the cost uncertainties within the hierarchical data structure of the complete product. We propose that only a holistic visualization containing both data and uncertainty can provide this kind of quick overview. Such a visualization must be able to visualize tree data structures associated with value attributes. After conducting interviews with product costing experts, we focused on Flow diagrams, which fulfill this basic requirement. However, they need to be extended in order to directly incorporate uncertainty information. We investigated three visualization techniques applicable to the ribbons of Flow diagrams to convey uncertainty information: Color-code, Gradient, and Margin. Moreover, we designed five visual approaches to show the uncertainty on nodes of Flow diagrams that we evaluated with visualization experts. The approaches add different geometries to the nodes such as triangles, blocks, or forks. The preferred solutions for the nodes was adding forks or filled blocks. With regards to the ribbons, we contribute a user study involving the solution of different product costing tasks using the three different visualizations. Although Gradient was considered an intuitive choice to show uncertainty, it yielded the highest error rates. In contrast, Color-code and Margin were superior depending on the performed task. Based on these findings and the subjective feedback, we designed an integrated approach that combines elements from all three distinct techniques and applied it to Sankey diagrams and Parallel sets.
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  • 37
    Publication Date: 2020-01-02
    Description: In this paper, we propose a transmitter with 150°divergence angle and more than 90% uniformity of rndiation intensity for quasi-omni-directional underwater wireless optical communication (UWOC) by applying freeform lens into LED array. We demonstrate its performance under different transmitting directions with 19Mbps data rate and 8m communication distance in an experimental tank whose volume is 20mx20mx14m and attenuation coefficient is about 0.40m-1. The result shows that the variation of bit error rate (BER) is about three orders of magnitude with the help of freefonn lens when direction deviation angle is between -75°and +75°, which is reduced five orders compared with the situation without the lens. The presented result is useful to make it easier lo establish communication link and improve the performance ofUWOC syste"1) when transmitter direction shake exists. Also, it implies that we could apply different freefonn lenses into LED array to reshape transmitting illumination according to different demands for UWOC application.
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  • 38
    Publication Date: 2020-01-02
    Description: In this study, an idealized eddy-resolving model is employed to examine the interplay between the downwelling, ocean convection and mesoscale eddies in the Labrador Sea and the spreading of dense water masses. The model output demonstrates a good agreement with observations with regard to the eddy field and convection characteristics. It also displays a basin mean net downwelling of 3.0 Sv. Our analysis confirms that the downwelling occurs near the west Greenland coast and that the eddies spawned from the boundary current play a major role in controlling the dynamics of the downwelling. The magnitude of the downwelling is positively correlated to the magnitude of the applied surface heat loss. However, we argue that this connection is indirect: the heat fluxes affect the convection properties as well as the eddy field, while the latter governs the Eulerian downwelling. With a passive tracer analysis we show that dense water is transported from the interior towards the boundary, predominantly towards the Labrador coast in shallow layers and towards the Greenland coast in deeper layers. The latter transport is steered by the presence of the eddy field. The outcome that the characteristics of the downwelling in a marginal sea like the Labrador Sea depend crucially on the properties of the eddy field emphasizes that it is essential to resolve the eddies to properly represent the downwelling and overturning in the North Atlantic Ocean, and its response to changing environmental conditions.
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  • 39
    Publication Date: 2020-01-02
    Description: Laccase-like multicopper oxidases (LMCOs) are a heterogeneous group of oxidases, acting mainly on phenolic compounds and which are widespread among many microorganisms, including Basidiomycetes and Ascomycetes. Here, we report the cloning, heterologous expression, purification and characterization of a novel LMCO from the thermophilic fungus Thermothelomyces thermophila. The 1953 bp lmco gene sequence comprises of 3 exons interrupted by 2 introns and according to the LccED database the translated sequence belongs to superfamily 6 of multicopper oxidases. After removal of the introns, the gene was transformed into Pichia pastoris, under the control of the alcohol oxidase (AOX1) promoter. The heterologous enzyme was purified with an apparent molecular weight of 80 kDa. TtLMCO1 displayed optimum activity at pH 4 and 50 °C and appeared thermostable up to 50 °C. A variety of phenolic compounds were oxidized by TtLMCO1, including standard laccase substrates such as ABTS and 2,6 dimethoxyphenol. The UV/Vis spectrum of purified TtLMCO1 indicates that it belongs to yellow laccase-like oxidases. The enzyme was used for the bioconversion of 2′,3,4-trihydroxychalcone to 3′,4′-dihydroxy-aurone, a bioactive aurone recently shown to possess inhibitory activity against several isoforms of the histone deacetylase complex (HDAC). Overall, the thermophilic yellow LMCO TtLMCO1 presents a number of superior properties with potential use in industrial biocatalysis.
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  • 40
    Publication Date: 2020-01-02
    Description: Highlights • Methane hydrate formation was studied by low-field NMR technology under formation conditions. • The spatial distribution of methane hydrate is heterogeneous. • The mechanism of methane hydrate formation in small pores is different from that in large pores. • Methane hydrate tends to form in the pore center of sandstone. Abstract Kinetics of hydrate formation in the porous media is important for carbon storage and the feasibility assessment of developing natural gas hydrates. In this study, we used a novel and real-time monitoring apparatus which combined the hydrate formation system with the low-field nuclear magnetic resonance measurement system to study on the characteristics of methane hydrate formation in a partially saturated sandstone. Results show that hydrate coexists with water and methane in the sandstone at the end of methane hydrate formation by an excess-gas method. Magnetic resonance imaging shows that the spatial distribution of hydrate is affected by the initial distribution of water in the sandstone. Water content plays a role in controlling the termination of hydrate formation. Based on the transverse relaxation time distribution analysis, free gas exists mainly in the large pores, while methane molecules can enter the small pores by dissolution and diffusion, forming methane hydrate with water molecules in the absence of free gas. Methane hydrate is formed in the center of both large and small pores by the excess-gas method. The rate of methane hydrate formation is slower in the small pores than that in the large pores. The range of pore size gradually decreases with the hydrate formation.
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  • 41
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    Elsevier
    In:  Current Opinion in Biotechnology, 57 . pp. 137-144.
    Publication Date: 2020-01-02
    Description: Mixed culture anaerobic processes are important to environmental systems, including the global carbon cycle, and industrial and environmental biotechnology. Mixed culture metabolic modelling (MM) is an essential tool to analyse these systems. MM predicts microbial function based on knowledge or assumption of cellular metabolism. It may be developed based on observations at the process level – biochemical process modelling (BPM) or fundamental knowledge of the cell being modelled – cellular level modelling (CLM). There is a substantial gap between these two fields, with BPM not considering genetic constraints, particularly where this may be important to interspecies interactions (e.g. amino acid transfer), and CLM commonly not considering mass transfer principles, such as advection/diffusion/migration. No unified approach is useful for all applications, but there is an increasing need to consider genetic information and constraints in developing BPM, and translate BPM principles (including mass-transfer and inorganic chemistry) for application to CLM.
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  • 42
    Publication Date: 2020-01-02
    Description: Even though ca 1746 people and over 3000 cattle were killed in 1986 by sudden release of about 800 million m3 of CO2 from Lake Nyos volcano in northwest Cameroon, the lake's formation history is not known. Here we report results of a lithostratigraphic and petrogenetic study of Nyos volcano that allows us to confirm its phreatomagmatic (maar) origin. Eruptive products are divided into 2 units, the phases of each of which are closely related in time. Unit A comprises 4 phases, the last (A-4) represents the cataclysmic phreatomagmatic formation of Nyos maar and may have been triggered by collapse of the vent system of the previous (A-1 to A-3) phases, and/or reactivation of basement faults. After a repose period, activity shifted NE of the maar to form Unit B products. The B-1 phase of this unit deposited the scoria now covering most of the Lake Nyos area. Unit B-2 constructed the Fon's cone. A small lava flow (Unit B-3) represents the latest phase of volcanic activity of Nyos volcano. Based on area-thickness estimation methods, a total of ca 0.8 km3 of eruptive material was produced from the volcano. Geochemical data suggest that magma of the 2 units probably formed by melting of the same garnet-bearing OIB-like asthenospheric mantle source, and evolved mainly by crustal contamination and fractional crystallization in independent magma batches that erupted without mixing. Our results provide a basis for advice on general hazard mitigation in the Lake Nyos area.
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  • 43
    Publication Date: 2020-01-02
    Description: Rivers are an important source of marine anthropogenic litter, but the particular origins of riverine litter itself have not been well established. Here we used a citizen science approach where schoolchildren examined litter at riversides and identified possible sources at over 250 sampling spots along large and small rivers in Germany, during autumn 2016 and spring 2017. Litter densities have an overall median of 0.14, interquartile range 0–0.57 items m−2 and an overall average (±standard deviation) of 0.54 ± 1.20 litter items m−2. Litter quantities differed only little by sampling year. The principal litter types found were plastics and cigarette butts (31% and 20%, respectively), followed by glass, paper, and metal items, indicating recreational visitors as the principal litter source. At many sites (85%), accumulations of litter, consisting principally of cigarettes and food packaging, have been found. At almost all sampling sites (89%), litter potentially hazardous to human health has been observed, including broken glass, sharp metal objects, used personal hygiene articles and items containing chemicals. In the search for litter sources, the schoolchildren identified mainly people who use the rivers as recreational areas (in contrast to residents living in the vicinity, illegal dumping, or the river itself depositing litter from upstream sources). These results indicate the urgent need for better education and policy measures in order to protect riparian environments and reduce input of riverine litter to the marine environment.
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  • 44
    Publication Date: 2020-01-02
    Description: Thrombospondin 1 (TSP-1) is an extracellular matrix protein that interacts with a wide array of ligands including cell receptors, growth factors, cytokines and proteases to regulate various physiological and pathological processes. Constitutively expressed by certain ocular surface tissues (e.g. corneal and conjunctival epithelium), TSP-1 expression is modulated during ocular surface inflammation. TSP-1 is an important activator of latent TGF-β, serving to promote the immunomodulatory and wound healing functions of TGF-β. Mounting research has deepened our understanding of how TSP-1 expression (and lack thereof) contributes to ocular surface homeostasis and disease. Here, we review current knowledge of the function of TSP-1 in dry eye disease, ocular allergy, angiogenesis/lymphangiogenesis, corneal transplantation, corneal wound healing and infectious keratitis.
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  • 45
    Publication Date: 2020-01-02
    Description: The aim of this study was to test the effect of long-term dissolved CO2 exposure on white grouper (Epinephelus aeneus). 45 day post hatching (dph) groupers (0.4 ± 0.05 g; 2.1 ± 0.1 cm) were equally distributed to 15 aquaria (17 L) at a density of 40 larvae per aquarium. The fish were grown for 60 days at a salinity of 25 ppt (26.5 οC) while being exposed to three dissolved CO2 concentrations: Control (0.8 ± 0.1 mg L−1; pH 7.9 ± 0.1), Medium (5.5 ± 0.2 mg L−1; pH 7.1 ± 0.1) and High (28.5 ± 1.5 mg L−1; pH 6.2 ± 0.1). Analysis of bone mineral contents showed that at the end of the CO2 exposure period (105 dph), the Ca levels were significantly higher (P 〈 .001) in the skeleton of fish from the high CO2 treatment as compared to the medium and control treatments. However, the P levels were not significantly different between the three treatments (P 〉 .05). The gene expression of bone Gla protein (BGP, Osteocalcin), a marker for skeletal mineralization, was significantly higher in the vertebral column of the fish from the control treatment as compared to the medium (P 〈 .05) and high (P 〈 .01) treatments. The expression of BGP mRNA was positively correlated with the fish growth rate, as the fish from the control treatment presented the highest body weight at the end of the experiment.
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  • 46
    Publication Date: 2020-01-02
    Description: We discuss several continuum cell-cell adhesion models based on the underlying microscopic assump-tions. We propose an improvement on these models leading to sharp fronts and intermingling invasionfronts between different cell type populations. The model is based on basic inciples of localizedrepulsion and nonlocal attraction due to adhesion forces at the microscopic level. The new model isable to capture both qualitatively and quantitatively experiments by Katsunuma et al. (2016) [J. CellBiol. 212(5), pp. 561–575]. We also review some of the applications of these models in other areas oftissue growth in developmental biology. We finally explore the resulting qualitative behavior due tocell-cell repulsion.
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  • 47
    Publication Date: 2020-01-02
    Description: The marine CO2 system in Tempelfjorden (Svalbard) was investigated between August 2015 and December 2017 using total alkalinity, pH, temperature, salinity, oxygen isotopic ratio, and nutrient data. Primary production resulted in the largest changes that were observed in the partial pressure of CO2 (pCO2, 140 μatm) and the saturation state of aragonite (ΩAr, 0.9). Over the period of peak freshwater discharge (June to August), the freshwater addition and air-sea CO2 uptake (on average 15.5 mmol m−2 day−1 in 2017) governed the surface pCO2. About one fourth of the uptake was driven by the freshening. The sensitivity of ΩAr to the freshwater addition was investigated using robust regressions. If the effect of air-sea CO2 exchange was removed from ΩAr, a freshwater fraction larger than 50% (lower range of uncertainty) was needed to provide aragonite undersaturated waters. This study shows that ΩAr and freshwater fraction relationships that are derived from regression techniques and the interpretation thereof are sensitive to the effect of air-sea CO2 exchange. Since the freshening in itself only drives a fraction of the air-sea CO2 uptake, studies that do not account for this exchange will overestimate the impact of freshwater on ΩAr. Finally, in the summer an excess in the salinity normalized dissolved inorganic carbon, corrected for aerobic primary production/respiration, of on average 86 μmol kg−1 was found in the deepest water of the fjord. This excess is suggested to be a result of enhanced CO2 uptake and brine release during the period of sea ice growth.
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  • 48
    Publication Date: 2020-01-02
    Description: The effect of ocean currents on fish eggs and larvae during their journey from spawning to nursery grounds in the Southern Benguela upwelling system is poorly understood. The survival and successful transport of fish eggs and larvae results from complex biological and physical processes. This study focuses on the advective processes, more specifically on how the dynamics and characteristics of the ocean currents shape the Lagrangian pathways in the Southern Benguela. A mesoscale eddy resolving interannual (1989–2010) simulation of the region, with a horizontal resolution of 7.5 km, is used to study processes impacting the connectivity between the western edge of the Agulhas Bank and the west coast upwelling region. A set of Lagrangian experiments are conducted with particles being released within the top 100 m of the water column along an across-shore transect off Cape Point (34∘ S). Transport success is given by the ratio of the number of particles that reach St Helena Bay (32∘ S) over the total number of particles released. The model results show a strong seasonal cycle in transport success which is governed by the complex three-dimensional structure of the along-shore jets, their variability, together with the wind-induced Ekman drift. Transport success is most efficient in spring when the Benguela Jet consists of one coherent intensified single-core branch that flows over the 300 m isobath, and when wind-induced Ekman transport favours the retention of particles within the jet. At this time of the year, the pathway leading to successful transport is located inshore, with 90% of particles released inshore the 300 m isobath being successfully transported to St Helena Bay in 〈15 days. This pathway is also characterized by low eddy kinetic energy values. During the upwelling season (December–March), transport success becomes less efficient, and less sensitive to the initial across-shore position of the particles. The inshore route no longer dominates, as the majority of particles follow offshore pathways. The Benguela Jet shifts offshore and splits into several branches due to the shoaling of the poleward undercurrent. The entrainment of particles within the offshore branch of the jet is favored by the dominating offshore wind-induced Ekman transport. Particles trapped in the offshore branch get exposed to higher mesoscale variability. Their northward progression is slower, which leads to journeys generally exceeding 20 days. This study shows that successful transport from the Agulhas Bank to the west coast upwelling region cannot be attributed to only a simple wind induced modulation of the jet. It explores how the seasonal modulation of the Benguela Jet, poleward undercurrent and offshore Ekman transport combine together with the turbulent off-shelf eddy field to set-up the characteristics of transport success.
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  • 49
    Publication Date: 2020-02-05
    Description: Among comparative metabolomic studies used in marine sciences, only few of them are dedicated to macroalgae despite their ecological importance in marine ecosystems. Therefore, experimental data are needed to assess the scopes and limitations of different metabolomic techniques applied to macroalgal models. Species of the genus Lobophora belong to marine brown algae (Family: Dictyotaceae) and are widely distributed, especially in tropical coral reefs. The species richness of this genus has only been unveiled recently and it includes species of diverse morphologies and habitats, with some species interacting with corals. This study aims to assess the potential of different metabolomic fingerprinting approaches in the discrimination of four well known Lobophora species (L. rosacea, L. sonderii, L. obscura and L. monticola). These species present distinct morphologies and are found in various habitats in the New Caledonian lagoon (South-Western Pacific). We compared and combined different untargeted metabolomic techniques: liquid chromatography-mass spectrometry (LC-MS), nuclear magnetic resonance (1H-NMR) and gas chromatography (GC-MS). Metabolomic separations were observed between each Lobophora species, with significant differences according to the techniques used. LC-MS was the best approach for metabotype distinction but a combination of approaches was also useful and allowed identification of chemomarkers for some species. These comparisons provide important data on the use of metabolomic approaches in the Lobophora genus and will pave the way for further studies on the sources of metabolomic variations for this ecologically important macroalgae.
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  • 50
    Publication Date: 2020-07-24
    Description: The growing demand for aquaculture products can only be maintained by increasing the production of lower trophic species such as bivalves and tunicates. Low trophic species avoid the energy losses during trophic transfers to build animal protein, making them ideal candidates to exploit available resources in coastal waters. In the particular case of fjords, forced upwelling of deep nutrient-rich waters can promote phytoplankton growth, or in other words, the growth of bivalve and tunicate food. However, the density at which bivalves and tunicates are cultured can compromise phytoplankton populations and consequently, marine food chains. A highly configurable environmental model was constructed to study the ecosystem effects and potential biomass production of hypothetical bivalve and tunicate aquaculture scenarios in a Norwegian fjord under forced upwelling conditions. The simulations objectively determined the level of aquaculture development that maximizes the sustainable utilization of resources towards bivalves and tunicates biomass production. The model also highlighted the positive effect of the forced upwelling on both cultured production and phytoplankton abundance under aquaculture scenarios. Finally, the model predicted that tunicates would be more efficient than mussels at extracting resources due to their lower metabolic cost and higher filtration capacity. Although a full economic analysis would be required to decide on the preferred species to be cultured, these results encourage current pilot studies in which tunicates are explored as a sustainable way to efficiently exploit marine resources for aquafeed production.
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  • 51
    Publication Date: 2020-01-02
    Description: A new mucin-binding lectin (AFL) was isolated from the marine sponge Aplysina fulva. AFL was purified by affinity chromatography on Sepharose™ matrix. Its hemagglutinating activity was independent of divalent ions, and it was weakly inhibited by simple sugars. However, porcine stomach mucin was a powerful inhibitor. In SDS PAGE, piridylethylated AFL showed one band of approximately 16 kDa, whereas in the non-reducing conditions, AFL showed at least two bands of 30 and 70 kDa. Mass spectrometry MALDI-ToF analysis showed one major ion of 31,652 ± 5 Da, which corresponded to a dimer formed by subunits linked by disulfide bonds. The first fifteen amino acids of AFL were determined, and no sequence similarity was observed with any known protein. Internal sequences were obtained by mass spectrometry analysis of tryptic digestion of AFL spots. These peptides showed similarity with a lectin from marine sponge Aplysina lactuca. Secondary structure of AFL was predominantly formed by β-conformations, which were stable at variations of pH and temperature. AFL did not inhibit planktonic growth of Gram-positive and Gram-negative bacteria tested. However, the lectin did significantly reduce the biomass biofilm of the bacteria Staphylococcus aureus, S. epidermidis, and Escherichia coli.
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  • 52
    facet.materialart.
    Unknown
    Elsevier
    In:  Pharmacological Research, 147 . p. 104373.
    Publication Date: 2020-01-02
    Description: Marine natural products represent novel and diverse chemotypes that serve as templates for the discovery and development of therapeutic agents with distinct mechanisms of action. These genetically encoded compounds produced by an evolutionary optimized biosynthetic machinery are usually quite complex and can be difficult to recreate in the laboratory. The isolation from the source organism results in limited amount of material; however, the development of advanced NMR technologies and dereplication strategies has enabled the structure elucidation on small scale. In order to rigorously explore the therapeutic potential of marine natural products and advance them further, the biological characterization has to keep pace with the chemical characterization. The limited marine natural product supply has been a serious challenge for thorough investigation of the biological targets. Several marine drugs have reached the markets or are in clinical trials, where those challenges have been overcome, including through the development of scalable syntheses. However, the identification of mechanisms of action of marine natural products early in the discovery process is potentially game changing, since effectively linking marine natural products to potential therapeutic applications in turn triggers motivation to tackle challenging syntheses and solve the supply problem. An increasing number of sensitive technologies and methods have been developed in recent years, some of which have been successfully applied to marine natural products, increasing the value of these compounds with respect to their biomedical utility. In this review, we discuss advances in overcoming the bottlenecks in marine natural product research, emphasizing on the development and advances of diverse target identification technologies applicable for marine natural product research.
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  • 53
    Publication Date: 2021-01-08
    Description: To better understand the formation of high-temperature metamorphic rocks, we present a detailed petrological and geochronological study of recently discovered cordierite-bearing granulites of the South Liaohe Group in the Jiao-Liao-Ji Belt, North China Craton. Petrographic observations indicate that four distinct mineral assemblages are present in the granulites: pre-peak amphibolite facies (M1), peak granulite facies (M2), post-peak decompression (M3), and late cooling retrogression (M4). M1 is preserved as fine-grained inclusions in the cores of garnet grains, represented by quartz + plagioclase + biotite + ilmenite. M2 is interpreted to have comprised garnet + sillimanite + plagioclase + quartz + biotite + ilmenite + melt. M3 was characterized by the formation of cordierite + sillimanite symplectites and cordierite + quartz coronas replacing garnet. M4 is indicated by the formation of staurolite, accompanied by the crystallization of melt. A combination of multi-equilibria geothermobarometers and pseudosection modeling constrains the P–T conditions of the M1, M2, M3, and M4 stages to P = 0.66–0.71 GPa and T = 620–650 °C, P = 0.96–1.10 GPa and T = 790–840 °C, P = 0.62–0.65 GPa and T = 725–785 °C, and P = 0.43–0.55 GPa and T = 595–625 °C, respectively. Zircon and monazite U–Pb dating yields three distinct and meaningful ages for the granulites: (1) 2200–2100 Ma for the granulite protoliths, (2) ca. 1945 Ma for the near-peak metamorphism, and (3) 1851–1839 Ma for the post-peak and late retrogressive metamorphism. Thus, a clockwise P–T–t path is determined for the cordierite-bearing granulites of the South Liaohe Group. Petrological and geochronological evidence from regional metamorphic rocks in the Jiao-Liao-Ji Belt suggests that the belt experienced a continuous orogenesis from 1950 to 1800 Ma.
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  • 54
    Publication Date: 2021-01-08
    Description: Correlation of the Paleoproterozoic rocks of the Korean Peninsula and China has been considered to be important for the tectonic evolution of Northeast Asia, yet it is still unclear. Recently considerable new data have been obtained from the Korean Peninsula and China providing a better opportunity to correlate the Paleoproterozoic rocks of the Korean Peninsula and China. Intermediate–P/T metamorphism and post–collisional magmatism have been found to have occurred during ca. 1.95–1.83 Ga not only in the Jiao–Liao–Ji belt on the eastern North China Craton but also in the Nangrim and northern Gyeonggi Massifs within the Korean Peninsula representing that these Paleoproterozoic rocks can be correlated. These events occurred as a result of the collision between the Longgang Block of the eastern North China Craton and the Nangrim Massifs of the Korean Peninsula. On the other hand, the southeastern Gyeonggi Massif underwent an arc–related magmatic and metamorphic events during ca. 1.96–1.91 Ga suggesting that the Paleoproterozoic rocks in southeastern Gyeonggi Massif cannot be correlated with those in northern Gyeonggi Massif. The Yeongnam Massif is unlikely correlated to the Nangrim and northern Gyeonggi Massifs and the eastern North China Craton because arc–related igneous activity occurred during ca. 2.00–1.85 Ga in the Sobaeksan Gneiss Complex in the central to northeastern Yeongnam Massif. The Jirisan Gneiss Complex in the southwestern Yeongnam Massif underwent intermediate–P/T metamorphism that is followed by post–collisional magmatic and low–P/T metamorphic events during ca. 1.92–1.86 Ga and these events may be correlated to those in the eastern Cathaysia Block on the South China Craton. The Paleoproterozoic correlation between the Korean Peninsula and China in this study supports a tectonic model in which the Permo–Triassic Dabie–Sulu continental collision belt in China extends into the Hongseong–Odaesan collision belt in the Gyeonggi Massif within the Korean Peninsula.
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  • 55
    Publication Date: 2020-02-05
    Description: In the southern zone of the Paleoproterozoic Jiao-Liao-Ji Belt (JLJB), North China Craton (NCC), abundant granitic leucosomes are widespread within migmatites as irregular layers, lenses, and blocks. They are parallel to or as cross-cut foliations in the host rocks on various scales, and show distinct evidence of migmatization in the formation of these centimeter- to decimeter-scale segregations. The migmatites extend at least 1100 km in length, spreading over the whole JLJB, from the Ji’an Group in south Jilin, through the South Liaohe Group in Liaodong Peninsula, to the Jingshan Group in Jiaodong Peninsula, rather than as sporadic outcrops limited to the Jiaobei Terrane as reported in previous studies. The granitic leucosomes are comprised mainly of quartz, K-feldspar, and antiperthitic plagioclase (albite), with secondary minerals of garnet, biotite, zircon, etc. They are enriched in SiO2 (74.65–75.54 wt%), Al2O3 (13.25–14.87 wt%), and K2O + Na2O (8.19–8.95 wt%), but have a lower TiO2 + Fe2O3 + FeO + MgO + MnO content (0.42–1.34 wt%). The major element components are similar to those of granitic leucosomes of pelitic granulites in typical orogenic belts around the world. A combined study of whole-rock geochemistry, mineral inclusions, cathodoluminescence (CL) images, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dates of zircons revealed the nature and timing of partial melting of the host pelitic granulites. All dated anatectic zircons from various granitic leucosomes display magmatic zones with distinct cores and rims, and contain mineral inclusions of Qtz + Kfs + Ab ± Ap in both domains. Both the cores and rims exhibit unusually high U and Th contents, and anomalously low Th/U ratios (〈0.10), indicative of an anatectic origin. The anatectic zircon cores and rims from eight granitic leucosome samples in the Ji’an and Liaohe groups exhibit two distinct weighted mean age groups ranging from 1870 ± 8 to 1865 ± 9 Ma and 1843 ± 13 to 1835 ± 11 Ma, with age peaks at ca. 1868 ± 3 Ma and 1841 ± 4 Ma, respectively. Similarly, abundant anatectic zircon cores and rims from granitic leucosomes in the Jingshan Group from the Jiaobei Terrane also showed two distinct groups with age peaks at 1862 ± 2 Ma and 1843 ± 3 Ma, respectively. These two distinct age groups can be interpreted as the initial timing of partial melting and crystallization end age of melts for the migmatites in the whole JLJB. The southern zone of the JLJB experienced a complicated granulite facies metamorphic evolution characterized by clockwise P-T-t paths, rather than anticlockwise P-T-t paths as reported in previous studies. The post-peak MP-LP granulite facies retrogression with a near isothermal decompression P-T path occurred at 1870–1840 Ma, which is completely consistent with the ages of partial melting. These age data provide powerful evidence that the widespread partial melting event within the southern zone of the JLJB occurred at the post-peak near-isothermal decompression stage, rather than at the peak granulite facies stage or the late amphibolite facies cooling stage. Thus, decompression melting is a major control factor on the generation of partial melting, and formation of the granitic leucosomes and migmatites within the southern zone of the JLJB. Under water-unsaturated conditions, hydrous minerals such as biotite underwent dehydration melting, and water released from the biotite results in felsic minerals occurring partial melting. These lines of evidence suggest that the pelitic granulites in the JLJB underwent intensive partial melting during the MP-LP granulite facies “hot” exhumation stage related to the extension and thinning tectonic setting. The resultant melts did not escape from the host rocks, leading to regionally extensive migmatization and subsequent retrogression.
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  • 56
    Publication Date: 2021-01-08
    Description: Poor pancreatic cancer (PC) prognosis has been attributed to its resistance to apoptosis and propensity for early systemic dissemination. Existing therapeutic strategies are often circumvented by the molecular crosstalk between cell-signalling pathways. p53 is mutated in more than 50% of PC and NFκB is constitutively activated in therapy-resistant residual disease; these mutations and activations account for the avoidance of cell death and metastasis. Recently, we demonstrated the anti-PC potential of fucoidan extract from marine brown alga, Turbinaria conoides (J. Agardh) Kützing (Sargassaceae). In this study, we aimed to characterize the active fractions of fucoidan extract to identify their select anti-PC efficacy, and to define the mechanism(s) involved. Five fractions of fucoidan isolated by ion exchange chromatography were tested for their potential in genetically diverse human PC cell lines. All fractions exerted significant dose-dependent and time-dependent regulation of cell survival. Fucoidans induced apoptosis, activated caspase −3, −8 and −9, and cleaved Poly ADP ribose polymerase (PARP). Pathway-specific transcriptional analysis recognized inhibition of 57 and 38 nuclear factor κB (NFκB) pathway molecules with fucoidan-F5 in MiaPaCa-2 and Panc-1 cells, respectively. In addition, fucoidan-F5 inhibited both the constitutive and Tumor necrosis factor-α (TNFα)-mediated NFκB DNA-binding activity in PC cells. Upregulation of cytoplasmic IκB levels and significant reduction of NFκB-dependent luciferase activity further substantiate the inhibitory potential of seaweed fucoidans on NFκB. Moreover, fucoidan(s) treatment increased cellular p53 in PC cells and reverted NFκB forced-expression-related p53 reduction. The results suggest that fucoidan regulates PC progression and that fucoidans may target p53–NFκB crosstalk and dictate apoptosis in PC cells.
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  • 57
    Publication Date: 2021-01-08
    Description: The anthropogenic marine debris, especially abandoned, lost or otherwise discarded Fishing Gear (ALDFG), represents a rising concern, because of its potential harmful impact on the marine animal forests. We carried out 13 km of video recordings, by means of a remotely operated vehicle, from 10 to 210 m depth, in an anthropised area of the Tyrrhenian Sea (Mediterranean Sea). This site, for its high ecological importance and biodiversity value, has been identified for the establishment of a new marine protected area (MPA). The aim of this paper was to assess marine litter abundance and its effects on the benthic fauna. The debris density, in the study area, ranged from 0.24 to 8.01 items/100 m2, with an average of 3.49 (±0.59) items/100 m2. The derelict fishing gear, mainly fishing lines, were the main source of marine debris, contributing 77.9% to the overall litter. The impacts of debris on the benthic fauna were frequently recorded, with 28.5% of the litter entangling corals and impacting habitats of conservation concern. These impacts were exclusively caused by the derelict fishing gear (91.2% by longlines), and the highest percentage (49.1%) of ALDFG causing impacts was observed from 41 to 80 m depth, in the coralligenous biocenosis. The results of the present study will help the fulfilment of “harm” monitoring, as recommended by the Marine Strategy Framework Directive (MSFD) and the UN Environment/MAP Regional Plan on the marine litter management in the Mediterranean Sea. Regarding the actions to reduce the derelict fishing gear, preventive measures are usually preferred instead of the extensive removals based on cost-effectiveness and sustainability. The establishment of a new MPA in the area could be a good solution to reduce ALDFG, resulting in the improvement of the ecological status of this coastal area.
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  • 58
    facet.materialart.
    Unknown
    Elsevier
    In:  Physics of the Earth and Planetary Interiors, 293 (Article number 106267).
    Publication Date: 2021-01-08
    Description: The southeast (SE) Asia - Australia collision zone is one of the most tectonically active and seismogenic regions in the world. Here, we present new 3-D P- and S-wave velocity models of the crust and upper mantle by applying regional earthquake travel-time tomography to global catalogue data. We first re-locate earthquakes provided by the standard ISC-Reviewed and ISC-EHB catalogues using a non-linear oct-tree scheme. A machine learning algorithm that clusters earthquakes depending on their spatiotemporal density was then applied to significantly improve the consistency of travel-time picks. We used the Fast Marching Tomography software package to retrieve 3-D velocity and interface structures from starting 1-D velocity and Moho models. Synthetic resolution and sensitivity tests demonstrate that the final models are robust, with P-wave speed variations (~130 km horizontal resolution) generally recovered more robustly than S-wave speed variations (~220 km horizontal resolution). The retrieved crust and mantle anomalies offer a new perspective on the broad-scale tectonic setting and underlying mantle architecture of SE Asia. While we observe clear evidence of subducted slabs as high velocity anomalies penetrating into the mantle along the Sunda arc, Banda arc and Halmahera arc, we also see evidence for slab gaps or holes in the vicinity of east Java. In the Banda arc, we image the slab as a single curved subduction zone. Furthermore, a high-velocity region in the mantle lithosphere connects northern Australia with Timor and West Papua. The S-wave model shows broad-scale features similar to those of the P-wave model, with mantle earthquakes generally distributed within high-velocity slabs. The high velocity mantle connection between northern Australia and the eastern margin of the Sunda arc is also present in the S-wave model. While the S-wave model has a lower resolution than the P-wave model due to the availability of fewer paths, it nonetheless provides new and complementary insights into the structure of the upper mantle beneath southeast Asia.
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  • 59
    facet.materialart.
    Unknown
    Elsevier
    In:  Physics of the Earth and Planetary Interiors, 293 (Article number 106267).
    Publication Date: 2021-01-08
    Description: The southeast (SE) Asia - Australia collision zone is one of the most tectonically active and seismogenic regions in the world. Here, we present new 3-D P- and S-wave velocity models of the crust and upper mantle by applying regional earthquake travel-time tomography to global catalogue data. We first re-locate earthquakes provided by the standard ISC-Reviewed and ISC-EHB catalogues using a non-linear oct-tree scheme. A machine learning algorithm that clusters earthquakes depending on their spatiotemporal density was then applied to significantly improve the consistency of travel-time picks. We used the Fast Marching Tomography software package to retrieve 3-D velocity and interface structures from starting 1-D velocity and Moho models. Synthetic resolution and sensitivity tests demonstrate that the final models are robust, with P-wave speed variations (~130 km horizontal resolution) generally recovered more robustly than S-wave speed variations (~220 km horizontal resolution). The retrieved crust and mantle anomalies offer a new perspective on the broad-scale tectonic setting and underlying mantle architecture of SE Asia. While we observe clear evidence of subducted slabs as high velocity anomalies penetrating into the mantle along the Sunda arc, Banda arc and Halmahera arc, we also see evidence for slab gaps or holes in the vicinity of east Java. Furthermore, a high-velocity region in the mantle lithosphere connects northern Australia with Timor and West Papua. The S-wave model shows broad-scale features similar to those of the P-wave model, with mantle earthquakes generally distributed within high-velocity slabs. The high velocity mantle connection between northern Australia and the eastern margin of the Sunda arc is also present in the S-wave model. While the S-wave model has a lower resolution than the P-wave model due to the availability of fewer paths, it nonetheless provides new and complementary insights into the structure of the upper mantle beneath southeast Asia.
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  • 60
    Publication Date: 2021-01-08
    Description: Dissimilatory sulfate reduction mediated by sulfate-reducing microorganisms (SRMs) has a pivotal role in the sulfur cycle, from which the generation of zero valent sulfur (ZVS) represents a novel pathway. Molecular details in the sulfite reduction to sulfide are still in debate. Also, the community composition and metabolic potential in sulfate-to-ZVS microbial communities remain to be elucidated. In this study, we employed genome-centric metagenomics approach to investigate the major players in a sulfate-to-ZVS bioreactor (ZVS-SR). Totally 51 metagenome assembled genomes (MAGs) were retrieved from the ZVS-SR microbiome, most belonging to phyla Proteobacteria, Actinobacteria, Bacteroides and Chloroflexi. Major players possibly responsible for ZVS generation included Desulfobacter, Desulfococcus, Desulfobacula and Desulfobacterales. A Desulfobacterales bacterium (SRB-bin23) was selected for subsequent detailed characterization of genome-encoded metabolic pathways and key functional genes involved in ZVS generation. This study expands our knowledge on the dissimilatory sulfate reduction in SRMs and may have important environmental implications.
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  • 61
    facet.materialart.
    Unknown
    Elsevier
    In:  In: Encyclopedia of Ocean Sciences. , ed. by Cochran, J. K., Bokuniewicz, H. J. and Yager, P. L. Elsevier, London, pp. 684-705. 3. edition
    Publication Date: 2020-03-02
    Description: Foraminifera are immensely successful and diverse components of deep-sea benthic communities, encompassing an extraordinary range of morphotypes and ecological traits. Bathymetric and geographic distributions are strongly influenced by organic-matter fluxes and carbonate dissolution. Species occupying different microhabitats within the sediment exhibit different ecological characteristics. Shallow-infaunal species are often active in processing labile organic matter and show seasonal population fluctuations; deeper infaunal species are less responsive and have more stable populations. Some foraminifera are highly tolerant of hypoxia, exhibiting ultrastructural and physiological adaptations to these stressful conditions, including the ability to respire nitrate. The structure and composition of fossil foraminiferal assemblages, and geochemical signals preserved in their calcareous shells, provide important proxies for reconstructing ancient oceans, particularly during the Late Cenozoic.
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  • 62
    Publication Date: 2021-01-08
    Description: Interactions between nano/microplastics and suspended sediment (SS) in natural waters are important for the environmental fate of plastic particles. This study investigated the effect of heteroaggregation between nano/microplastics and SS on the settling of aggregates. In NaCl solutions (0.05–0.5 M), large SS (100–500 μm in diameter) significantly increased the settling ratio of polystyrene nanoplastics (PSNPs) with an average diameter of 100 nm due to the formation of PSNPs-SS aggregates. The settling ratio of the heteroaggregates increased significantly when the NaCl concentration increased from 50 to 200 mM. This was primarily because higher ionic strength reduced the electrostatic repulsion between large SS and PSNPs, and subsequently increased the heteroaggregation rate. No obvious differences in settling ratios were observed in 200 or 500 mM NaCl solutions because the heteroaggregation entered the diffusion-controlled regime. However, in HA solutions (10–50 mg L−1), the surface adsorption of HA on PSNPs and large SS reduced the heteroaggregation of PSNPs-SS and thus led to the low co-settling ratio due to the steric hindrance according to the DLVO theory. In contrast, polyethylene microplastics (PEMPs) with diameters of 1.0–1.2 mm were found to always float on water surface (up to 8 months), even after addition of 500 mg L−1 small SS (〈10 μm in diameter). Clearly, the heteroaggregation of PEMPs and small SS had minor effect on the settling of PEMPs due to the overwhelming boyanccy. These results provided new insight into the fate and distribution of nano/microplastics in aquatic environment, which affect the bioavailability of plastic particles in natural waters.
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  • 63
    Publication Date: 2021-01-08
    Description: Microplastic pollution within the marine environment is of pressing concern globally. Accordingly, spatial monitoring of microplastic concentrations, composition and size distribution may help to identify sources and entry pathways, and hence allow initiating focused mitigation. Spatial distribution patterns of microplastics were investigated in two compartments of the southern North Sea by collecting sublittoral sediment and surface water samples from 24 stations. Large microplastics (500−5000 μm) were detected visually and identified using attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The remaining sample was digested enzymatically, concentrated onto filters and analyzed for small microplastics (11−500 μm) using Focal Plane Array (FPA) FTIR imaging. Microplastics were detected in all samples with concentrations ranging between 2.8 and 1188.8 particles kg−1 for sediments and 0.1–245.4 particles m−3 for surface waters. On average 98% of microplastics were 〈100 μm in sediments and 86% in surface waters. The most prevalent polymer types in both compartments were polypropylene, acrylates/polyurethane/varnish, and polyamide. However, polymer composition differed significantly between sediment and surface water samples as well as between the Frisian Islands and the English Channel sites. These results show that microplastics are not evenly distributed, in neither location nor size, which is illuminating regarding the development of monitoring protocols.
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  • 64
    Publication Date: 2021-01-08
    Description: Changes in the characteristics of cyclone activity (frequency, depth and size) in the Arctic are analyzed based on simulations with state-of-the-art regional climate models (RCMs) from the Arctic-CORDEX initiative and global climate models (GCMs) from CMIP5 under the Representative Concentration Pathway (RCP) 8.5 scenario. Most of RCMs show an increase of cyclone frequency in winter (DJF) and a decrease in summer (JJA) to the end of the 21st century. However, in one half of the RCMs, cyclones become weaker and substantially smaller in winter and deeper and larger in summer. RCMs as well as GCMs show an increase of cyclone frequency over the Baffin Bay, Barents Sea, north of Greenland, Canadian Archipelago, and a decrease over the Nordic Seas, Kara and Beaufort Seas and over the sub-arctic continental regions in winter. In summer, the models simulate an increase of cyclone frequency over the Central Arctic and Greenland Sea and a decrease over the Norwegian and Kara Seas by the end of the 21st century. The decrease is also found over the high-latitude continental areas, in particular, over east Siberia and Alaska. The sensitivity of the RCMs' projections to the boundary conditions and model physics is estimated. In general, different lateral boundary conditions from the GCMs have larger effects on the simulated RCM projections than the differences in RCMs' setup and/or physics.
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  • 65
    Publication Date: 2020-11-12
    Description: Carbonate escarpments are submarine limestone and dolomite cliffs that have been documented in numerous sites around the world. Their geomorphic evolution is poorly understood due to difficulties in assessing escarpment outcrops and the limited resolution achieved by geophysical techniques across their steep topographies. The geomorphic evolution of carbonate escarpments in the Mediterranean Sea has been influenced by the Messinian salinity crisis (MSC). During the MSC (5.97–5.33 Ma), the Mediterranean Sea became a saline basin due to a temporary restriction of the Atlantic-Mediterranean seaway, resulting in the deposition of more than one million cubic kilometres of salt. The extent and relative chronology of the evaporative drawdown phases associated to the MSC remain poorly constrained. In this paper we combine geophysical and sedimentological data from the central Mediterranean Sea to reconstruct the geomorphic evolution of the Malta Escarpment and infer the extent and timing of evaporative drawdown in the eastern Mediterranean Sea during the MSC. We propose that, during a MSC base-level fall, fluvial erosion formed a dense network of canyons across the Malta Escarpment whilst coastal erosion developed extensive palaeoshorelines and shore platforms. The drivers of geomorphic evolution of the Malta Escarpment after the MSC include: (i) canyon erosion by submarine gravity flows, with the most recent activity taking place 〈2600 cal. years BP; (ii) deposition by bottom currents across the entire depth range of the Malta Escarpment; (iii) tectonic deformation in the southern Malta Escarpment in association with a wrench zone; (iv) widespread, small-scale sedimentary slope failures preconditioned by oversteepening and loss of support due to canyon erosion, and triggered by earthquakes. We carry out an isostatic restoration of the palaeoshorelines and shore platforms on the northern Malta Escarpment to infer an evaporative drawdown of 1800–2000 m in the eastern Mediterranean Sea during the MSC. We interpret the occurrence of pre-evaporite sedimentary lobes in the western Ionian Basin as suggesting that either evaporative drawdown and canyon formation predominantly occurred before salt deposition, or that only the latest salt deposition at the basin margin occurred after the formation of the sedimentary lobes.
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  • 66
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    Elsevier
    In:  In: Encyclopedia of Ocean Sciences. Elsevier, ., pp. 437-444. ISBN 978-0-12-813082-7
    Publication Date: 2020-02-17
    Description: The Peru-Chile Current System (PCCS) is the combined name for the equatorward and poleward currents along the Chilean and Peruvian coasts. The PCCS is a “typical” eastern boundary current system with predominately coast parallel equatorward winds, intensive upwelling, and high biological productivity. An important peculiarity of the PCCS is its tight connection to the equatorial Pacific communicating the globally strongest mode of interannual variability, the “El Niño/Southern Oscillation”, into the region. In addition, at intermediate depths, the PCCS region hosts one of the most intense oxygen-minimum zones that reaches from the coastal areas into the open ocean and influences the ecology and biogeochemical cycling in the region.
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  • 67
    Publication Date: 2021-01-08
    Description: The selection of suitable and indigenous microalgae species is a fundamental requirement in developing added-value bioactive compounds recoverable in the food, health, and cosmetics markets. In this work, an integrated screening approach was developed to characterize the lipid rate of 33 diatom species (including 15 species studied for the first time) belonging to 16 genera from the Nantes Culture Collection, with the main objective of discovering bioactive lipid producers. For that purpose, a simple reliable method for establishing growth kinetics of strains and semi-quantitative analysis of lipid rates was developed. Growth kinetics measurements were achieved by daily minimal measurement fluorescence (F0) whereas lipid rate analyses were performed by high-throughput Fourier Transform Infrared spectroscopy on entire cells and lipid extracts. Results indicated that the method could be used directly on entire cells in spite of the presence of silica for the FTIR approach (due to frustule). The total lipid rate was species-dependant and ranged from 3.7% to 30.5% DW. Six strains out of 33 were found to present a higher total lipid rate superior to 15% DW, and 11 showed medium lipid rates ranging from 10% to 15% DW. The results revealed that five diatom species i.e. Amphora sp. NCC169, Nitzschia sp. NCC109, Nitzschia alexandrina NCC33, Opephora sp. NCC366 and Staurosira sp. NCC182 presented interesting growth capabilities and should be further investigated as potential sources for their original lipid rate.
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  • 68
    Publication Date: 2021-01-08
    Description: The development of natural-based anti-tumor medicaments has acquired a great interest especially in the last few decades. Hence, cytotoxic activity of different fractions of fucoidan was evaluated. The fractions, produced from the total crude extract of the brown alga Fucus vesiculosus and purified by the recently-developed immobilized cationic dyes at different conditions, had different physicochemical properties and named fucoidan_1, fucoidan_6 and fucoidan_PDD. The activity of these fractions was studied in vitro against different kinds of cancerous mammalian cell lines including MCF-7 and Caco-2 and compared to their effects against skin primary fibroblasts. The results indicated a potent cytotoxic activity with regard to MCF-7 cells, while negligible (〉1500 μg mL−1) towards primary fibroblasts. Moreover, higher general toxicity of crude fucoidan indicated that purification process succeeded to remove extraneous, co-extracted, cytotoxic compounds (e.g., polyphenols), which has a strong activity and possible interference in previously-published studies. Furthermore, a correlation was made between the cytotoxic activity and physico-chemical properties of fucoidan fractions, such as the sulfation degree and molecular weight. These findings reflected a real picture and expected low side effects regarding the cytotoxic activity of fucoidan purified by affinity chromatography.
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  • 69
    Publication Date: 2021-01-08
    Description: Curvulamine is a novel framework alkaloid with prominent antibacterial and acetylcholinesterase inhibitory activities produced by marine fungus, Curvularia sp. IFB-Z10. However, the low yield severely restricts its further pharmaceutical researches and applications. The study was aimed to enhance curvulamine production based on CaCl2 addition strategy and further clarify the underlying regulation mechanism of Ca2+. In this work, the optimal addition conditions of CaCl2 were firstly obtained, and curvulamine production achieved 42.96 mg/L under supplying 5 mM CaCl2 at 0 h, which was 3.33-fold that of control in shake flask. It was further found that cytosolic Ca2+ level was markedly increased through calcium channel under CaCl2 stimulation. Relatively high intracellular Ca2+ level could induce fungus to principally form pellets with small diameter and compact structure (morphology), and significantly up-regulate the transcriptional and expression levels of key biosynthetic genes, which collectively promoted curvulamine synthesis. Finally, CaCl2 addition strategy was successfully applied in 5-L bioreactor. This work provided an effective regulation strategy to improve curvulamine production in submerged fermentation of Curvularia sp. and it would facilitate further research on the synthesis regulation of secondary metabolites from other marine filamentous fungi.
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  • 70
    Publication Date: 2021-01-08
    Description: Climate drivers are key stress factors affecting upland rice yields in Sahel because the region is vulnerable to unfavorable weather and has a very low adaptive capacity. This study modeled upland rice yield responses to climate factors using multiple linear regression, boosted tree regression, and artificial neural networks (ANNs). Four ANNs were explored: ANNMLP (multilayer perceptron), ANNPNN (probabilistic neural network), ANNGFF (generalized feedforward), and ANNLR (linear regression). Then the modeled rice yield function was calibrated and tested against the observed yield data and climate variables of three provinces of Burkina Faso, West Africa. The global climate model (GCM) outputs under the AR4-SR-A1B, A2, and B1 mean ensemble CO2 emissions scenarios were then downscaled and used as input of the calibrated yield response model, in order to forecast yield trends over 2052. The results are three-fold: first, rain (R = 0.402) is the most dominant climate driver in Sahel, followed by the maximum and minimum temperatures (R = -0.313 and R = -0.237, respectively), which clearly reduce yield. Second, the ANNPNN (R = 0.952, MSE = 0.033 ton/ha, NMSE = 0.109 ton/ha, MAE = 0.115 ton/ha) has a great capability in rice yield responses function modeling outperforming boosted tree (R = 0.920, MSE = 0.077 ton/ha, NMSE = 0.208 ton/ha, MAE = 0.223 ton/ha) and the multiple linear regression (R = 0.385, MSE = 0.259 ton/ha, NMSE = 0.852 ton/ha, MAE = 0.340 ton/ha). All linear models performed unsatisfactorily. Third, the projected yields showed a gap of 57.29% with the site-recorded maximum average yields over 2052. From application of ANNPNN, we anticipate that site-specific rice yield may substantially decline with climate change, as rainfall is projected to decrease while temperatures increase. These results should assist in identifying priority adaptation measures for Sahel, such as village rainwater catchment basins supplemented with adapted irrigation technologies, to enhance the resilience of crops.
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  • 71
    Publication Date: 2021-02-08
    Description: The formation of toxic disinfection by-products (DBPs) is among the main concerns in the use of chlorine sanitizers for washing fresh and fresh-cut produce to minimize microbial cross-contamination. Even so, robust analytical methods for measuring various DBPs in produce have been lacking. This study has established two liquid-liquid extraction methods, followed by gas chromatography with electron capture detection, to measure 32 conventional and emerging DBPs in different produce types including lettuce, cabbage and strawberry. Good recoveries (50–130%) were achieved for most DBPs in the different produce. The method detection limits were in the range of 0.3–10 ng/g for trihalomethanes, haloacetic acids, nitrogenous DBPs, and other carbonaceous DBPs. Preliminary screening analysis indicated one-third of the target DBPs were found in unwashed produce, and washing with chlorine significantly promoted DBPs’ formation and concentrations in the produce. The developed analytical methods will be useful tools for future research on food DBPs.
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  • 72
    Publication Date: 2020-01-17
    Description: Changes in labile organic carbon in wetland soils as indicators of soil quality and climate change have received attention worldwide. Soil samples were collected in 2012 and 2013 in estuarine wetlands with different water tables in the Yellow River Delta, and soil salinity, water content (WC), microbial biomass carbon (MBC), and dissolved organic carbon (DOC) were determined to investigate the effects of water and salinity on labile organic carbon in wetland soils. Our results showed that the response of labile organic carbon to salt and water conditions was different in soil samples with different water tables. The MBC in soils with low water tables (LW) was the lowest when soil WC was 25% and then exhibited an increase with increasing WC. The DOC in LW soils increased and MBC and DOC contents in soils with middle water tables (MW) and high water tables (HW) decreased with increasing WC. MBC in three wetlands presented a “decreasing before increasing” tendency with increasing salinity, whereas DOC totally showed an “increasing before decreasing” tendency. Soil microbial biomass and soil fertility in estuarine wetlands with salinity between 1.8 and 2.0 ppt were relatively high, which was conducive to plant growth. The findings of this study will be helpful to better understand the relationships between soil labile organic carbon and water and salt conditions in estuarine wetlands and provide basic data for carbon sequestration and blue carbon management of estuarine wetlands.
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  • 73
    Publication Date: 2021-01-08
    Description: Eutrophication and subsequent harmful cyanobacteria blooms are global water quality problems, and identifying the key drivers of water eutrophication and estimating nutrient thresholds for it in waterbodies have long been challenges for water quality managers. Data-intensive machine learning models have been shown to be better able to reveal the nonlinear relationships between variables in the study of complex biotic community dynamics than traditional mechanistic models. In this study, we applied random forest models to long-term datasets from nutrient monitoring and meteorological observations to characterize the relationships between algal growth and different environmental drivers in three eutrophic lakes in China. We further attempted to estimate the season-specific nutrient thresholds in these lakes, and assess the potential decreases in chlorophyll a concentrations that could be achieved through nutrient management. In general, chlorophyll a concentrations predicted by the random forest models were consistent with the values observed in the lakes, and successfully displayed the same seasonal variations. The estimated total nitrogen (TN) and total phosphorus (TP) nutrient thresholds were quite variable among months, and were higher in summer than in winter. To maintain chlorophyll a concentrations below 20 μg/L, the estimated TN thresholds in Lakes Taihu, Dianchi, and Chaohu in August were 2145 ± 683, 2372 ± 918 and 1527 ± 71 μg/L (mean ± standard deviation), respectively, and the corresponding TP thresholds were 82 ± 24, 149 ± 22, and 120 ± 22 μg/L. The modelling results indicated that it was more important to control the TP concentrations in these lakes than the TN concentrations to control algal growth in summer. In summary, the strong seasonal variation in the estimated nutrient thresholds suggests that a ‘one-size-fits-all’ nutrient control target could overprotect these water bodies. Seasonal variation in nutrient concentrations and environmental drivers should thus be considered when establishing nutrient criteria and setting nutrient control targets.
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  • 74
    Publication Date: 2021-01-08
    Description: Background Nutritional well-being is the prerequisite condition for a sustainable improvement in human welfare. Human gut microbiota plays a magnificent role in balancing the condition of metabolic syndrome management. Currently, the gut microbiome mediated immune system is gaining attention for the treatment of several health ailments such as diabetes, gastrointestinal disorders, and malnourishment. Bioactive compounds from marine polysaccharides from seaweeds are found beneficial for enhancing the activity of gut microbes. Scope and approach There were limited reviews in recent times to discuss the updates on extraction, purification and biological activities of dietary fibers using non-conventional methods. The present review inspects on the proximal and structural composition of seaweed polysaccharides and their methods of extraction and purification aspects. It also focuses on the immune modulating mechanisms of prebiotic-probiotic synergetic interaction by stimulating beneficial gut microbial activity and by the production of short-chain fatty acids. The mutual relationship between prebiotics and probiotics that leads to a healthy gut was targeted in the present review. Key findings and conclusions Marine seaweeds polysaccharides are the untapped bioresources to be explored for its biotherapeutic properties of dietary fibers. The practical complications on extracting polysaccharides by a single technique could be overcome by adopting the strategy of utilizing combinatorial extraction and purification techniques. Its prebiotic effect aids in the enhancement of gut microbial activity by exhibiting the properties of non-digestibility, fermentability, and pathogen inhibition potential. The impending benefits of dietary fiber from seaweed polysaccharides as prebiotics for formulating functional food ingredients along with probiotic microbes to exhibit immunomodulation applications. Therefore, intended human clinical trials should be carried out to evaluate and discover the probiotic-prebiotic relationship in the human gut, which could step out the research to the next level in the medicinal world.
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  • 75
    Publication Date: 2021-01-08
    Description: Background Recently, the study of marine natural products has gained interest due to their relevant biological activities. Specially, seaweeds produce bioactive compounds that could act as modulators of cell signaling pathways involved in a plethora of diseases. Thereby, the description of the molecular mechanisms by which seaweeds elicit its biological functions will certainly pave the way to the pharmacological development of drugs. Aim This review describes the molecular mechanisms by which seaweeds act and its possible utilization in the design of new drugs. Methods This review was conducted according to the PRISMA-P guidelines for systematic reviews. Two independent authors searched into four different databases using combinations of keywords. Two more authors selected the articles following the eligibility criteria. Information extraction was conducted by two separated authors and entered into spreadsheets. Methodological quality and risk of bias were determined applying a 12-question Risk of Bias criteria tool. Results and discussion We found 2360 articles (SCOPUS: 998; PubMed: 678; Wiley: 645 and EBSCO: 39) using the established keywords, of which 113 articles fit the inclusion criteria and were included in the review. This work comprises studies in cell lines, and animal models, any clinical trial was excluded. The articles were published from 2005 up to March 31st 2018. The biggest amount of articles was published in 2017. Furthermore, the seaweeds tested in the studies were collected in 15 countries, mainly in Eastern countries. We found that the main modulated signaling pathways by seaweeds-derivate extracts and compounds were: L-Arginine/NO, TNF-α, MAPKs, PI3K/AKT/GSK, mTOR, NF-κB, extrinsic and intrinsic apoptosis, cell cycle, MMPs and Nrf2. Finally, the articles we analyzed showed moderate risk of bias in almost all the parameters evaluated. However, the studies fail to describe the place and characteristics of sample collection, the sample size, and the blindness of the experimental design. Conclusion In this review we identified and summarized relevant information related to seaweed-isolated compounds and extracts having biological activity; their role in different signal pathways to better understand their potential to further development of cures for cancer, diabetes, and inflammation-related diseases.
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  • 76
    Publication Date: 2021-01-08
    Description: Algae biomass comprises variety of biochemicals components such as carbohydrates, lipids and protein, which make them a feasible feedstock for biofuel production. However, high production cost mainly due to algae cultivation remains the main challenge in commercializing algae biofuels. Hence, extraction of other high value-added bioproducts from algae biomass is necessary to enhance the economic feasibility of algae biofuel production. This paper is aims to deliberate the recent developments of conventional technologies for algae biofuels production, such as biochemical and chemical conversion pathways, and extraction of a variety of bioproducts from algae biomass for various potential applications. Besides, life cycle evaluation studies on microalgae biorefinery are presented, focusing on case studies for various cultivation techniques, culture medium, harvesting, and dewatering techniques along with biofuel and bioenergy production pathways. Overall, the algae biorefinery provides new opportunities for valorisation of algae biomass for multiple products synthesis.
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  • 77
    Publication Date: 2021-01-08
    Description: Twelve terpenoids, including two new 3,5-dimethylorsellinic acid-based meroterpenoids (1 and 2) and two new monoterpenoids (11 and 12), were obtained from the deep-sea fungus Penicillium sp. YPGA11. Their structures were determined by extensive analyses of spectroscopic data, and the absolute configurations of 1 and 2 were determined by comparisons of experimental and calculated ECD spectra. Compounds 1 and 2, bearing a 23-aldehyde or 23-carboxylic acid group, were rarely found in compounds with similar carbon skeleton. All compounds but 11 were evaluated for inhibitory effects towards nitric oxide production induced by lipopolysaccharide in RAW 264.7 macrophage cells. Compound 9 exhibited significant inhibitory effects with an IC50 value of 7.58 μM, being comparable to the positive control, quercetin (10.97 μM).
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  • 78
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    Elsevier
    In:  In: Encyclopedia of Ocean Sciences Vol. 2. , ed. by Steel, J. H. Elsevier, London, England, pp. 684-705, 22 pp. 3rd edition
    Publication Date: 2020-05-04
    Description: Foraminifera are immensely successful and diverse components of deep-sea benthic communities, encompassing an extraordinary range of morphotypes and ecological traits. Bathymetric and geographic distributions are strongly influenced by organic-matter fluxes and carbonate dissolution. Species occupying different microhabitats within the sediment exhibit different ecological characteristics. Shallow-infaunal species are often active in processing labile organic matter and show seasonal population fluctuations; deeper infaunal species are less responsive and have more stable populations. Some foraminifera are highly tolerant of hypoxia, exhibiting ultrastructural and physiological adaptations to these stressful conditions, including the ability to respire nitrate. The structure and composition of fossil foraminiferal assemblages, and geochemical signals preserved in their calcareous shells, provide important proxies for reconstructing ancient oceans, particularly during the Late Cenozoic.
    Type: Book chapter , NonPeerReviewed
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  • 79
    Publication Date: 2021-01-08
    Description: Natural gas hydrate (NGH) has been widely considered as an alternative form of energy with huge potential, due to its tremendous reserves, cleanness and high energy density. Several countries involving Japan, Canada, India and China have launched national projects on the exploration and exploitation of gas hydrate resources. At the beginning of this century, an early trial production of hydrate resources was carried out in Mallik permafrost region, Canada. Japan has conducted the first field test from marine hydrates in 2013, followed by another trial in 2017. China also made its first trial production from marine hydrate sediments in 2017. Yet the low production efficiency, ice/hydrate regeneration, and sand problems are still commonly encountered; the worldwide progress is far before commercialization. Up to now, many gas production techniques have been proposed, and a few of them have been adopted in the field production tests. Nevertheless, hardly any method appears really promising; each of them shows limitations at certain conditions. Therefore, further efforts should be made on the economic efficiency as well as sustainability and environmental impacts. In this paper, the investigations on NGH exploitation techniques are comprehensively reviewed, involving depressurization, thermal stimulation, chemical inhibitor injection, CO2–CH4 exchange, their combinations, and some novel techniques. The behavior of each method and its further potential in the field test are discussed. The advantages and limitations of laboratory studies are also analyzed. The work could give some guidance in the future formulation of exploitation scheme and evaluation of gas production behavior from hydrate reservoirs.
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  • 80
    Publication Date: 2021-01-08
    Description: Numerical modeling shows great potential as a method for investigating and predicting the future development of ice shelves in a warming climate. The quality of ice shelf-ocean models is continuously improving but some limitations remain. For models using a terrain-following vertical coordinate, one such limitation is the enforcement of a minimum water-column thickness beneath ice shelves by adjustment of bottom topography. How this local distortion of bathymetry from reality affects modeled melt rates and cavity circulation is unknown so far. To quantify this effect, simulations with the Finite Element Sea ice–ice shelf–Ocean Model (FESOM) were executed on four different grids with minimum water-column thicknesses of 20 m, 50 m, 100 m and 200 m. While we use a global model grid, modifications of bathymetry are applied only to Filchner–Ronne Ice Shelf. We show that the choice of minimum water-column thickness does not affect the total basal melt rate of this cold-water ice shelf but does in fact impact the distribution of melt rates with significant differences between experiments in the magnitude of melting near the grounding lines.
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  • 81
    Publication Date: 2020-01-17
    Description: Four contrasting coastal systems in Ireland, each with shellfish production activities, were studied to provide a first evaluation of the spatial and seasonal influences on the local carbonate system. The study sites included; (1) a coastal system with sandstone bedrock and minimal freshwater sources, (2) an estuarine system with a catchment limestone bedrock, (3) an estuarine system with a catchment granite bedrock, and (4) a karst groundwater-fed estuary. The type of bedrock was the dominant control on regional carbonate chemistry, where the calcium carbonate catchment bedrock was a strong source of both dissolved inorganic carbon and total alkalinity input in the two limestone regions, which are supersaturated with respect to atmospheric CO2 throughout the year. Primary production played an important role in the non-limestone regions, where both systems were CO2-undersaturated during productive months. Minimum aragonite saturation () was observed at all sites during winter when productivity is lowest; surface winter is 〈1.5 close to the mussel farms in Kinvara Bay and Bantry Bay. was recalculated to account for the higher calcium concentrations in the River Suir from limestone dissolution, which increases by 0.5 in the mid estuary and 〉2 in the inner estuary. The substrate-to-inhibitor ratio (SIR), an alternative indicator of ecosystem vulnerability to acidification, was positively correlated to in all systems, however with more variability in the two limestone regions. Results highlight challenges of assessing local ecosystem vulnerability to future acidification and the importance of understanding the local spatio-temporal biogeochemistry.
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  • 82
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    Elsevier
    In:  Pharmacological Research, 147 . p. 104373.
    Publication Date: 2020-02-05
    Description: Marine natural products represent novel and diverse chemotypes that serve as templates for the discovery and development of therapeutic agents with distinct mechanisms of action. These genetically encoded compounds produced by an evolutionary optimized biosynthetic machinery are usually quite complex and can be difficult to recreate in the laboratory. The isolation from the source organism results in limited amount of material; however, the development of advanced NMR technologies and dereplication strategies has enabled the structure elucidation on small scale. In order to rigorously explore the therapeutic potential of marine natural products and advance them further, the biological characterization has to keep pace with the chemical characterization. The limited marine natural product supply has been a serious challenge for thorough investigation of the biological targets. Several marine drugs have reached the markets or are in clinical trials, where those challenges have been overcome, including through the development of scalable syntheses. However, the identification of mechanisms of action of marine natural products early in the discovery process is potentially game changing, since effectively linking marine natural products to potential therapeutic applications in turn triggers motivation to tackle challenging syntheses and solve the supply problem. An increasing number of sensitive technologies and methods have been developed in recent years, some of which have been successfully applied to marine natural products, increasing the value of these compounds with respect to their biomedical utility. In this review, we discuss advances in overcoming the bottlenecks in marine natural product research, emphasizing on the development and advances of diverse target identification technologies applicable for marine natural product research.
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  • 83
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    Elsevier
    In:  In: Encyclopedia of Ocean Sciences. , ed. by Cochran, J. K., Bokuniewicz, J. H. and Yager, L. P. Elsevier, Oxford, UK, pp. 189-203.
    Publication Date: 2020-12-16
    Type: Book chapter , NonPeerReviewed
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  • 84
    Publication Date: 2021-01-08
    Description: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) products have been widely applied due to their medical and healthcare value. In this paper, the methods for extracting DHA and EPA from microalgae and related purification methods were summarized and analyzed. The yields of DHA and EPA from different species of microalgae were investigated. The optimal extraction and purification methods and microalgae species that are suitable for the extraction of EPA and DHA products were determined. Currently, organic solvents are extensively used to extract oil from microalgal biomasses. The supercritical fluid extraction technique is an ideal method for lipid extraction. Based on the findings presented in this paper, a combination of multiple methods is a better choice to extract and purify EPA and DHA from microalgae.
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  • 85
    Publication Date: 2021-01-08
    Description: Time series of in situ surface seawater partial pressure of CO2 (pCO2) data collected between 2005 and 2017, together with other environmental variables from field or satellite measurements, along the coasts of the United States of America and its territories at different latitudes, are analyzed to separate the temperature effect from the remaining non-temperature effects (i.e., biological and other physical effects) on driving surface pCO2. Similar to the findings in the open ocean, on seasonal time scales, the temperature effect (pCO2_T) tends to override the non-temperature effect (pCO2_nonT) in modulating surface pCO2 in tropical and subtropical oceanic waters. However, the balance between pCO2_T and pCO2_nonT tends to shift towards pCO2_nonT in temperate zone waters, with a few exceptions in some specific oceanic environments. On interannual time scales, both atmospheric pCO2 and surface pCO2 show significant increasing trends over short time scales (i.e., 〈10 years) except for a few outliers. In tropical and subtropical waters, the interannual changes of surface pCO2 are mainly controlled by the non-temperature effect (through air-sea CO2 exchange). In temperate regions, these changes are primarily driven by the temperature effect (through increased SST). Considering that temperature is commonly included in remote sensing algorithms of surface pCO2, this study suggests that, to better capture the seasonal and interannual signals in surface pCO2 from satellites, atmospheric pCO2 must be considered in the surface pCO2 remote sensing algorithms especially in tropical and subtropical waters. The non-temperature effect on surface pCO2, especially the biological effect (e.g., algal blooms), needs further investigation.
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  • 86
    Publication Date: 2021-01-08
    Description: This paper introduces the Sobol’ indices approach for global sensitivity analysis (SA), in the context of marine biogeochemistry. Such an approach is particularly well suited for ocean biogeochemical models, which make use of numerous parameters within large sets of differential equations with complex dependencies. This SA allows for a detailed study of the relative influence of a large number of input parameters on output quantities of interest to be chosen. It is able to distinguish between direct effects of these parameters and effects due to interaction between two or more parameters. Although demanding in terms of computation, such a tool is now becoming affordable, thanks to the development of distributed computing environments. An applicative example is presented with the MODECOGeL biogeochemical model, and illustrates the advantages of this approach over standard local SA.
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  • 87
    Publication Date: 2021-01-08
    Description: Fucoidan is a marine-origin sulfated polysaccharide that can show anticancer activity, to which both pro- and anti-angiogenic responses have been reported. Due to this unpredictability, the angiogenic potential of an effective anticancer crude fucoidan (CF), at a concentration of 0.5 mg mL−1, was evaluated. Tube formation assays demonstrated that CF, either administered while endothelial cells seeding or after their adhesion, migration and organization, inhibited or disrupted the formation of tubular-like structures, respectively. Although CF did not significantly reduced vascular endothelial growth factor (VEGF) secretion, it significantly reduced the expression of platelet-derived growth factor (PDGF), compromising the blood vessels maturation. Two chicken embryo chorioallantoic membrane (CAM) assays were performed: one without tumor (CAM I) and the other with an onplanted tumor mass (CAM II); the CF injection reduced the number of blood of vessels and significantly decreased the tumor size, respectively. In vitro and in vivo results support the effectiveness of fucoidan as a natural antitumor therapeutic agent.
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  • 88
    Publication Date: 2021-01-08
    Description: Energy shortage and carbon emission reduction are the two big problems in the development of human society. The technologies involving CH4-CO2 binary hydrate is considered to be promising for CH4 recovery and carbon emission reduction. The DSC, Raman, FTIR, Cryo-SEM and PXRD are employed to investigate the thermal process, the micro structure and compositions of the CH4-CO2 hydrate formation and decomposition. The investigations reveal that there are not one kind of hydrate but rather multi-kinds of hydrates coexistence during the hydrate formation. The mechanism of gas hydrate formation could be considered as, under a certain condition, the component with lower enthalpy prior to entrap the cavities to stabilize the hydrate cages in the process of constructing hydrate cages by water molecules, and once the relevant cages are stabilized, the hydrates thereby exist. To fully disperse the oil additive (e.g. CP) into water can effectively improve the gas consumption and enhance CO2 separation efficiency in the process of CH4-CO2 binary hydrate formation. The methods presented here can also be employed for other fields such as hydrate-based sea-water desalination, CO2 separation and H2 purification from IGCC syngas, gas transportation, and other fields.
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  • 89
    Publication Date: 2020-01-17
    Description: Subaqueous slopes are susceptible to a broad range of failure mechanisms and deformation styles, many of which are not well characterised. We undertook novel laboratory-based testing using a Dynamic Back-Pressured Shearbox on samples collected from an area subject to ongoing slope failures, situated on the upper slope of New Zealand's Hikurangi Margin, to determine how increases in pore water and gas pressures generate shallow mass movement. Using both water and nitrogen gas we observed similar responses in both cases, indicating that behaviour is dominated by the normal effective stress state regardless of pore-fluid phase. Shear-strain accumulation, representing landslide movement, shows a slow episodic pattern, in common with many shallow terrestrial landslides. Our results are relevant for landslides occurring in shallow near surface sedimentary sequences but have implications for deep-seated landslide behaviour. They suggest that once movement initiates at a critical effective stress, its rate is regulated through dilation and pore expansion within the shear zone, temporarily increasing effective stress within a narrow shear band and suppressing rapid shear. Consequently, under certain conditions, shallow submarine landslides (e.g. spreading failures) can undergo slow episodic movement which allows them to accumulate large shear strains without accelerating to catastrophic movement even when they are unconstrained.
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  • 90
    Publication Date: 2021-01-08
    Description: The Temagami Anomaly is one of the largest unexplained magnetic features in North America. It is similar in size and shape to the geophysical anomaly that marks the 1.85 Ga Sudbury Igneous Complex (SIC) in its immediate vicinity but its geological cause and potential link to the Sudbury impact structure have remained elusive. Here we report on a 2200 m deep diamond drill core intersecting the area of maximum magnetic anomaly and provide evidence of diorite dykes therein being most likely related to the Sudbury impact event. The fine-grained, strongly altered biotite-amphibole diorite occurs below 2000 m, is intrusive into Archaean basement rocks and has the same major- and trace element geochemistry as the SIC, which approximates the bulk composition of the local continental crust that was hit by the impact. A crustal affinity analogous to SIC impact-melt rocks is further supported by whole-rock Nd and Pb isotopes. Low ɛNd0 between −27.6 and −18.7, as well as Nd model ages of 2.75 Ga are considered as inherited from the crustal precursor rocks that became largely homogenized in the course of impact melt formation. The 206Pb/204Pb ratios are between 15.77 and 19.38, 207Pb/204Pb between 15.22 and 15.59 (corresponding to initial 207Pb/204Pb at 1850 Ma between 15.14 and 15.22), yielding an “isochron age” of 1780 +320/−330 Ma, and the 208Pb/204Pb ranges from 35.47 to 41.15, all values that compare well with published data on SIC impact-related igneous rocks of mainly quartz dioritic composition, locally referred to as Offset Dykes, and that are distinctly different to those reported for other magmatic units in the wider region. Although several such dykes have been well known to occur both radially and concentrically around the SIC, none have been described so far from the area east of the SIC. The recognition of former intrusive impact melt at an even greater distance (50 km) from the SIC than has been known so far increases the extent of the impact structure but also the exploration potential of the area of the Temagami magnetic anomaly for Ni-Cu-PGE-sulfide deposits. The actual cause of the Temagami Anomaly remains open to debate.
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  • 91
    Publication Date: 2021-01-08
    Description: This research is focused on the composition of the sediments produced in volcanic islands when the climate does not favour weathering. The XRD mineralogy (bulk sample and fraction finer than 63 µm), petrography and geochemistry of a set of bedload stream and beach samples collected in the “old” Maio and the “young” Fogo islands of Cape Verde archipelago are used to investigate the compositional transformations promoted by exogenous processes during island denudation. The main factor responsible for the variability in sediment composition is the incorporation of biogenic material derived from the evolving shelves; it largely exceeds the effects of the exhumation of different volcanic and basement units. Given the arid climate (and steep land surface in Fogo), only the most labile components of basaltic rocks, such as volcanic glass, are decomposed. The incipient weathering and sorting processes are responsible for the depletion of Al in bedload deposits. The same happens with other elements usually regarded as non-mobile (namely, Nb, Th, REE, etc.), while Mg is concentrated. Thus, weathering indices grounded on the premise that “mobile” elements are lost and “non-mobile” elements are enriched via weathering are useless in Cape Verde bedload sediments. With time, weathering is able to promote Na leaching and the formation of secondary minerals, which tend to retain non-mobile elements released in the earlier stages of alteration (e.g., LREE, Th, Y, Nb, Ta etc.). Sorting processes are responsible for the selective removal of less-dense grains, explaining local differences between beach and stream deposits. Beach placers are enriched in augitic clinopyroxene (occasionally also in olivine in the Fogo island), and Sc, Cr and Co. Niobium and Ta must be hosted in fine-grained particles that are easily windblown and their abundances in dusts may reveal Cape Verde as a source of airborne material crossing the Atlantic Ocean.
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  • 92
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    Elsevier
    In:  Journal of Atmospheric and Solar-Terrestrial Physics, 187 . pp. 53-62.
    Publication Date: 2021-01-08
    Description: Relation of decadal variations of the North Atlantic Oscillation index (NAOI) to the 11-year solar cycle in the sunspot number is analyzed for almost 200-year observational period with the use of cross-spectral and cross-wavelet techniques. Based on wavelet transforms of a pair of time series, local cross characteristics such as the local coherency and local correlation are used to study time evolution of the solar–NAOI relationship. The analysis of the NAOI is supplemented and confirmed by similar analysis of more than 300-year long data of Central England temperature (CET). Both the solar cycle–NAOI and solar cycle–CET relationships exhibit a quasi-periodic oscillation with the mean period of about 50 years, which includes a subinterval with positive coherency and a subinterval with negative coherency between the solar cycle and the 11-year modes of the NAOI and CET. The same multidecadal modulation of the solar–NAOI relationship is manifested in the temporal structure of the local correlation between the 11-year modes of the NAOI and the sunspot number at specific time lags of the NAOI relative to the sunspot number. It is distinct in the local correlations for the extended winter period (November–March) NAOI lagging by 7 years after the sunspot number. At this lag, the NAOI anticorrelates in general with the sunspot number and the local anticorrelation reinforces periodically with the aforementioned ∼50 year period. At the 1-year lag, which differs from the 7-year lag by a half solar cycle, the 11-year mode of the winter NAOI correlates in general with the solar cycle but the correlation is mainly associated with the last 70-year time interval. The change in the sign of the solar–NAOI relationship is also the case for the extended summer periods of the year (May–September). For this period, the approximately mirror image of the local correlations is observed at the 7-year and 1-year lags. The multidecadal modulation is likely associated with periods of enhanced solar impact on the NAO.
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  • 93
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    Elsevier
    In:  In: Encyclopedia of Ecology. , ed. by Fath, B. D. Elsevier, Oxford, UK, pp. 108-115. 2. ed. ISBN 978-0-444-63768-0
    Publication Date: 2018-10-16
    Type: Book chapter , NonPeerReviewed
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  • 94
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    Elsevier
    In:  Journal of Petroleum Science and Engineering, 172 . pp. 855-877.
    Publication Date: 2020-01-02
    Description: Gas hydrates are crystalline ice-like structures formed from water and gas molecules at high pressure and low temperature conditions. They are considered as near-future energy resources. Recently, there have been many drilling activities in gas hydrates in both permafrost regions (mainly Mallik wells, Canada; Ignik Sikumi #1 well, Alaska; Mount Elbert #1, Alaska) and marine sediments (the wells drilled in Gulf of Mexico and India drilling expeditions). In this study, it is aimed to evaluate and analyze logging-while drilling data (LWD) and other drilling data of these drilling activities. Initially, all drilling parameters (i.e. rate of penetration, weight on bit, torques, mud logs, etc.) of these wells were collected and drawn to see the change in parameters with depths. In order to indicate the changes in drilling parameters in the sediments containing gas hydrates, gas hydrate saturations were estimated from resistivity logs and NMR logs in this study. High resistivity log values and methane peaks in drilling fluid were good indicators of gas hydrate existence. During the drilling of permafrost formations and gas hydrates deposited in coarse sands as pore filling, the rate of penetration generally decreased. Differently, there was not almost any change in the rate of penetration during the drilling of fracture-filling gas hydrates within silts/clay in India. Borehole enlargements (washouts) were commonly seen in the wells drilled in marine sediments (Gulf of Mexico and Indian expeditions). However, this effect was minimum during the drilling of the wells in permafrost regions. This difference is due to the loose sediments in marine environment. Furthermore, gamma and density logs were seriously affected by washouts, mainly in marine sediments. It was observed that pore-filling gas hydrates affect the rate of penetration and keep the sediments stable because well collapses mainly occurred in the sediments without any gas hydrates. However, the temperature of drilling fluid should be close to the temperature of gas hydrate zones to reduce the effect of drilling on gas hydrate dissociation for the wells both in permafrost and marine sediments. In Gulf Mexico and Indian drilling expeditions, riser and wellhead equipment were not used. However, the usage of surface casing might decrease the risk of borehole collapses due to very loose sediments close to sea floor. Another important outcome of this study is that the pressure gradient follows hydrostatic pressure gradients according to the pressure analysis within gas hydrate stability zones of marine sediments. Finally, the analyses of drilling parameters revealed that drilling through gas hydrate bearing strata is not as risky as it might have been considered. The key is hidden in appropriate drilling design.
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  • 95
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    Elsevier
    In:  In: Reference Module in Earth Systems and environmental Sciences. Elsevier, Rotterdam, Netherlands, pp. 204-211. ISBN 978-0-12-409548-9
    Publication Date: 2019-04-29
    Description: The Atlantic Ocean has been the most studied and best understood of the World Oceans, for the reason of its importance for the European and American societies. There is a growing evidence that the Atlantic circulation plays a crucial role in the Earth's climate. In this article we summarize our current knowledge of the large scale currents in the Atlantic as well as the variability of the circulation on multiple space and time scales. We also outline outstanding challenges for future oceanographic investigations of the Atlantic current systems.
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  • 96
    Publication Date: 2022-01-07
    Description: Highlights • The dissolution kinetics of roasted lizardite at different T and pH were studied. • An initial rapid liberation of Mg2+ followed by a very slow extraction was observed. • Increasing temperature caused an increase in the rate of Mg extraction initially. • The extent of extraction of Mg2+ decreased due to precipitation of silica. • Silica re-precipitation at high temperature and S/L was demonstrated. Abstract The dissolution of magnesium silicate minerals such as serpentine in aqueous solutions saturated or near saturated with carbon dioxide (CO2) enables its subsequent reaction to form magnesium carbonate, a process called aqueous mineral carbonation. The dissolution rate of magnesium ions (Mg2+) from thermally activated serpentine and the factors influencing the rate and extent of dissolution have been studied in our research group. The current contribution focuses on the effect of temperature and pH on the dissolution of heat activated lizardite (a polymorph of serpentine). The extent of dissolution of thermally activated lizardite was measured experimentally as a function of temperature (25 °C ≤ T ≤ 75 °C) and pH (1.2 ≤ pH ≤ 9.8). It was found that at higher temperatures the level of Mg extraction is greater during the initial stage of dissolution but is then hindered by the re-precipitation of amorphous silica. Thermodynamic modelling was used to assess the susceptibility of solid phase formation and confirmed the likelihood of re-precipitation of amorphous silica from the solutions. For the first time, in this work, the crackling core model (CCM) was used to model experimental data at different pH values.
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  • 97
    Publication Date: 2022-01-07
    Description: In seawater, trace metals occur in many forms: free ion, labile and non-labile complex, colloid, associated with particles, but only free ions and very labile metal complexes can cross the phytoplankton membrane and be assimilated. In this paper we review the most appropriate determination methods for those metal species, addressing particularly in situ speciation and preconcentration. Focus is on DGT-ICPMS, which is a technique that meets these criteria very well. In coastal environments, DGT probes are widely used for metal pollution monitoring, but in open ocean a carrier such as a glider, is required. In open ocean organic metal complexation has been studied using DGT-ICPMS and electrochemical methods. The use of DGTs with different diffusion domain thicknesses provides information to quantify labilities and dissociation rates of metal complex pools. Labilities of metal complexes in coastal waters appeared to be higher than in open sea.
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  • 98
    Publication Date: 2022-01-07
    Description: Highlights • Velocities of porous basalt decrease as a function of increasing porosity. • Velocities of porous basalt depend on pore aspect ratio. • Velocities of water ice-saturated basalt are higher than gaseous CO2- or liquid water-saturated basalt. • Presented modelling could improve interpretations of the seismic data collected by the InSight lander. The theoretical predictions for the P- and S-wave velocity of basalt with pore spaces filled with gaseous CO2, liquid water, or water ice presented herein could help improve interpretations of the seismic data collected by NASA's InSight lander, which landed on the Martian surface in November 2018.
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  • 99
    Publication Date: 2022-01-07
    Description: Highlights • In water-rich silicic systems effusions can be generated by magmas with higher water contents than explosions. • The paper presents the comparative example of effusive and explosive deposits erupted at Nisyros-Yali. • Explosive eruptions were generated by water-rich magmas that were water-undersaturated during pre-eruptive storage. • Effusive eruptions were generated by water-richer magmas that were water-supersaturated during pre-eruptive storage. • The role of pre-eruptive exsolved volatiles in controlling eruptive styles is explored. Arc volcanoes generally emit water-rich, high-viscosity silicic magmas, which are prone to erupt explosively. However, effusive behavior is a common occurrence despite the high-H2O, high viscosity conditions. The contrasting shift from effusive to explosive behavior (and vice-versa) at any individual volcano raises the question on what controls eruptive style. Permeability development in conduits allows magma to outgas and is clearly a key factor. However, an important question is whether magma reservoir processes can also have an influence on eruptive styles. The answer could have direct impact on predicting eruptive behavior. Hence, we explore this potential connection by analyzing nine alternating effusive and explosive silicic deposits that were emplaced during distinct eruptions at the active Nisyros-Yali volcanic center. The lavas and pyroclastic deposits are compositionally similar. This indicates a negligible influence of the bulk rock composition on different eruptive styles. The crystal contents vary between units, without any clear correlation with eruptive style (from nearly aphyric to ~45 vol% crystals). Mineral textures and chemistry do show variations between effusive and explosive eruptions, with a larger proportion of resorbed plagioclase and, in most cases, more evolved amphiboles present in the lava flows. Mineral thermo-barometry and hygrometry show that the storage zones of magmas generating effusive eruptions evolved towards colder and more water-rich conditions (710–790 °C; 5.6–6.5 wt% H2O) than their explosive counterparts (815–850 °C; 4.2–4.6 wt% H2O). At storage pressures of 1.5–2 kbar, relevant for Nisyros-Yali, the volatile saturation level is reached at 〉5 wt% H2O. Therefore, it is likely that the magmas reached water-saturation before generating effusive eruptions, and were undersaturated before explosive events. We hypothesize that the presence of exsolved volatiles in the subvolcanic reservoir can enhance the outgassing potential of the magma during conduit ascent. Hence, the rhyolitic effusive-explosive transitions can be influenced by the pre-eruptive exsolved versus dissolved state of the volatiles in the magma chamber. This can lead to the less explosive eruptions for the most water-rich reservoir conditions.
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  • 100
    Publication Date: 2022-01-07
    Description: Plastic debris has been recognized as a growing threat to marine biota due to its widespread distribution and possible interactions with marine species. Concerns over the effects of plastic polymers in marine ecosystems is reflected in the high number of toxicological studies, regarding microplastics (〈5 mm) and marine fauna. Although several studies reported that organisms ingest and subsequently eliminate microplastics (MP), the potential effects at organ and tissue level remain unclear, especially considering exposure to different microplastic sizes and concentrations. The present study aimed at investigating potential pathophysiological effects of the ingestion of MP by marine filter-feeders. For the purpose, Mediterranean mussel (Mytilus galloprovincialis) was exposed to spherical polystyrene MP (2 and 10 μm Ø) over short- and medium-term exposure periods, under single and combined concentrations that represent high, yet realistic doses (10 and 1000 MP mL−1). Overall, results suggest rapid MP’ clearance from water column by filtering, regardless of MP size. Ingestion occurred, identified by MP in the lumen of the gut (mostly in midgut region), followed by excretion through faeces. However, no MP were found in gills or digestive gland diverticula. Biochemical indicators for oxidative stress were generally irresponsive regardless of organ and time of exposure. Small foci of haemocytic infiltration in gastric epithelia were found, albeit not clearly related to MP ingestion. Globally, no evident histopathological damage was recorded in whole-body sections of exposed animals. The present findings highlight the adaptative ability of filter-feeding bivalves to cope with filtration of suspended MP, resulting in rapid elimination and reduced internal damage following ingestion of spherical MP. Nevertheless, the fact that the animals are able to translocate MP to the gut reveals that filter feeding organisms may indeed became a target of concern for fragmented materials with smaller, mixed sizes and sharper edges.
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