50 research outputs found
Modeling of a mixed?load fluvio?deltaic system
No full textPresent?day observations and classical classification schemes of alluvial deltas address feeder channel dynamics and multiple sediment fractions. However, high?resolution physics?based mathematical models have not been applied to address formation of both fluvio?deltaic links (channels) and nodes (diffluences and confluences), and their stratigraphy. Here, we present a simulated delta system under riverine forcing that shows striking similarity to its counterparts recognized in field and laboratory studies. These findings include distinct shifts in river planimetrical mode and altimetry, deltaic mouth bar and distributary formation, lateral fining in migrating?meander bend axes and fining?upward patterns in passive delta?plain distributaries.GeotechnologyCivil Engineering and Geoscience
The impact of changes in sediment supply and sea-level on fluvio-deltaic stratigraphy
No full textStudies in stratigraphy are often driven by the predicted climate change and possible gains for the oil and gas industry. Because, at present predictions of the development of future deltaic architecture are insufficient. This thesis addresses the problem of qualitative and quantitative understanding of sedimentary systems in two stages. In the first stage the stratigraphy of Holocene delta deposits of the Kura and Mahakam deltas (respectively in Azerbaijan en Indonesia) are studied. Results from these studies provide insights as an analogue to ancient systems and serve as an example for expected future conditions. The results form the Kura delta show a prominent role for the rapid sea-level change of the Caspian Sea, while the results of Mahakam delta suggest an important role for the eustatic Holocene sea-level curve and the absence of floods of the Mahakam River. Information obtained from studies in a similar context have the potential to reduce uncertainties and increase confidence in models. The second stage of this thesis covers the development of a process-response simulation model to assess the impact of changes in sediment supply and sea-level on fluvio-deltaic stratigraphy. Anticipating on the dominant role of sediment supply on fluvial dominated deltas, a choice is made for a detailed investigation in how to incorporate good estimates of sediment supply in the numerical model, that enable to explore the possibilities of using a probabilistic approach instead of a deterministic output or geostatistical analysis.Civil Engineering and Geoscience
Process-response simulation of fluvio-deltaic stratigraphy
No full textCivil Engineering and Geoscience
Fluopsin C for treating multidrug-resistant infections: In vitro activity aganist clinically important strains and in vivo efficacy against carbapenemase-producing Klebsiella pneumoniae
No full textThe increasing emergence of multidrug-resistant (MDR) organisms in hospital infectionsis causing a global public health crisis. The development of drugs with effective antibioticaction against such agents is of the highest priority. In the present study, the actionof Fluopsin C against MDR clinical isolates was evaluated underin vitroandin vivoconditions. Fluopsin C was produced in cell suspension culture ofPseudomonasaeruginosaLV strain, purified by liquid adsorption chromatography and identified bymass spectrometric analysis. Bioactivity, bacterial resistance development risk againstclinically important pathogenic strains and toxicity in mammalian cell were initiallydetermined byin vitromodels.In vivotoxicity was evaluated inTenebrio molitorlarvae and mice. The therapeutic efficacy of intravenous Fluopsin C administration wasevaluated in a murine model ofKlebsiella pneumoniae(KPC) acute sepsis, using sixdifferent treatments. Thein vitroresults indicated MIC and MBC below 2μg/mL and lowbacterial resistance development frequency. Electron microscopy showed that FluopsinC may have altered the exopolysaccharide matrix and caused disruption of the cell wallof MDR bacteria. Best therapeutic results were achieved in mice treated with a singledose of 2 mg/kg and in mice treated with two doses of 1 mg/kg, 8 h apart. Furthermore,acute and chronic histopathological studies demonstrated absent nephrotoxicity andmoderate hepatotoxicity. The results demonstrated the efficacy of Fluopsin C againstMDR organisms inin vitroandin vivomodels, and hence it can be a novel therapeuticagent for the control of severe MDR infectionspublishedVersion© 2019 Navarro, Simionato, Pérez, Barazetti, Emiliano, Niekawa, Andreata, Modolon, Dealis, Araújo, Carlos, Scarpelim, da Silva, Chryssafidis, Bruheim and Andrade. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms
Impacto da suplementação com extrato de Curcuma longa L. na microbiota intestinal de pacientes em hemodiálise
No full textResumo Introdução: O impacto da curcumina na microbiota intestinal de pacientes com doença renal crônica (DRC) não é bem conhecido. O objetivo deste estudo foi avaliar o efeito da Curcuma longa L. na microbiota intestinal de pacientes com DRC submetidos à hemodiálise (HD). Métodos: Análise secundária de dados provenientes de um ensaio clínico randomizado, duplo-cego e controlado por placebo. Os pacientes receberam 100 mL de suco de laranja, 12 gramas de cenoura e 2,5 gramas de Curcuma longa L., três vezes por semana, após a sessão de HD (grupo curcumina), ou o mesmo suco sem adição de curcumina (grupo controle) durante 12 semanas. A composição da microbiota fecal foi estimada utilizando sequenciamento de leitura curta da região V4 do gene 16S rRNA na plataforma Illumina. Resultados: Onze pacientes participaram deste estudo, cinco no grupo curcumina (66,7% homens, 59 ± 16,7 anos, tempo médio de hemodiálise de 97 ± 62,6 meses, IMC 25,3 ± 2,9 kg/m2) e seis no grupo controle (60% homens, 57,5 ± 12,5 anos, tempo médio de hemodiálise de 48,3 ± 32,2 meses, IMC 25,2 ± 3,1 kg/m2). A suplementação com extrato de Curcuma longa L. não alterou a biodiversidade alfa nem a composição taxonômica dos indivíduos nos níveis de filo, família e gênero. Conclusão: A suplementação com 2,5 g de extrato de Curcuma longa L., três vezes por semana durante 12 semanas, mostrou-se ineficaz na modulação da microbiota intestinal de pacientes com DRC em HD. Esses resultados devem ser interpretados levandose em consideração o pequeno tamanho da amostra, sendo recomendada a realização de estudos futuros com coortes maiores.<br
Alignment of fluvio-tidal point bars in the middle McMurray Formation: implications for structural architecture of the Lower Cretaceous Athabasca Oil Sands Deposit, northern Alberta
No full textThe northern Athabasca Oil Sands Deposit accumulated on sub-Cretaceous structure partially configured by multi-stage pre-Cretaceous salt dissolutions in Prairie Evaporite (Middle Devonian) substrate that continued concurrent with deposition of McMurray Formation (Aptian) strata. Dissolution fronts only 250 m below advanced along NW- and NE-oriented fracture-fault lineaments that coalesced into larger salt removal areas. This structural grain was transmitted to the overlying dissected Upper Devonian karst topography draped by lower McMurray braided rivers along a lattice-like channel network. The dominant NW structural grain continued during middle McMurray deposition with fluvial-estuarine point bars aligned along subparallel tidal channels. Regional salt removal fronts concurrent with middle McMurray deposition migrated north of the Bitumount Trough, resulting in the 200 km² central collapse. The northern Athabasca Deposit area was configured as a funnel-shaped lower estuary structure consisting of aligned Upper Devonian-lower McMurray fault block terraces that stepped down northward into the central collapse. Sinuous river channels of the upper estuary, constrained along stable substrate of the main paleovalley, flowed northward onto the unstable floor of this funnel-form lower estuary. The main paleovalley fairway branched into multiple 10s of km long sub-parallel fluvio-estuarine tidal channels aligned parallel to the NW structural grain. Sand transport fairways cascaded over the step down terraces and permitted aggradations of overlying fluvio-tidal point bars to accumulate into giant commercially attractive sand complexes. The internal architecture of these 10s of meters thick sand deposits included deposit-wide erosion surfaces resulting from cycles of collapse-subsidence, stabilized substrate and erosion, and renewed subsidence and aggradation.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Changjiang Delta in the Anthropocene: Multi-scale hydro-morphodynamics and management challenges
No full textThe Changjiang Delta (CD) is one of well-studied large deltas of critical socio-economical and ecological importance regionally and global representativeness. Cumulated field data and numerical modeling has facilitated scientific understanding of its hydro-morphodynamics at multiple spatial and time scales, but the changing boundary forcing conditions and increasing anthropogenic influences pose management challenges requiring integrated knowledge. Here we provide a comprehensive synthesis of the multi-scale deltaic hydro-morphodynamics, discuss their relevance and management perspectives in a global context, and identify knowledge gaps for future study. The CD is classified as a river-tide mixed-energy, muddy and highly turbid, fluvio-deltaic composite system involving large-scale land-ocean interacted processes. Its hydro-morphodynamic evolution exhibits profound temporal variations at the fortnightly, seasonal, and inter-annual time scales, and strong spatial variability between tidal river and tidal estuary, and between different distributary channels. As the river-borne sediment has declined >70%, the deltaic morphodynamic adaptation lags behind sediment decline because sediment redistribution within the delta emerges to play a role in sustaining tidal flat accretion. However, the deltaic channels have become narrower, deepened and growingly constrained under cumulated human activities, e.g., extensive embankment and construction of jetties and groins, possibly initiating a decrease in morphodynamic activities and sediment trapping efficiency. Overall, the CD undergoes transitions from net sedimentation and naturally slow morphodynamic adaptation to erosion and human-driven radical adjustment. A shift in management priority from delta development to ecosystem conservation provides an opportunity for restoring the resilience to flooding and erosion hazards. The lessons and identified knowledge gaps inform study and management of worldwide estuaries and deltas undergoing intensified human interferences.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Coastal Engineerin
Multi-scale simulation of fluvio-deltaic and shallow marine stratigraphy
No full textSimClast is a basin-scale 3D stratigraphic model, which allows several interacting sedimentary environments. We developed it from 2004 to 2008 at Delft University of Technology and implemented part of the Meijer (2002) code for accounting, loading and storing algorithms. SimClast is a fully plan view 2D, depth-averaged model, allowing the complex interaction between fluvial and wave influences on deltaic and shoreface development to be studied. It focuses on theoretical experiments, as quantitative experiments are intrinsically difficult to recreate in real world settings. Yet there lies the great strength of numerical modelling, as we can improve upon the understanding of these systems by focussing on the process forming and removing the deposits. The modelling applications focus especially on the erosional and nondepositional events as these probably represent the greatest amount of “stratigraphic time”. Short-term, high-resolution processes are coupled with the long-term stratigraphic model by nesting a parameterised version of the high-resolution processes. We extrapolate physical and empirical relationships of the geomorphological development and implement these. A necessary constraint on these long-term models is a relatively large grid sizing (i.e. km scale), as the area to be modelled is on the scale of continental margins and the modelling time is on the scale of many millennia. Areas of special importance are modelled by implementing sub-grid scale processes into a large-scale basin-filling model; this refines the model dynamics and the resulting stratigraphy. Processes included are; fluvial channel dynamics and overbank deposition, river plume deposition, open marine currents, wave resuspension, nearshore wave induced longshore and crosshore transport. This combined modelling approach allows insight into the processes influencing the flux of energy and clastic material and the effect of external perturbations in all environments. Many governing processes work on relatively small scales, e.g. in fluvial settings an avulsion is a relatively localised phenomenon, yet they have a profound effect on fluvial architecture. This means that the model must mimic these processes, but at the same time maintain computational efficiency. Additionally, long-term models use relatively large grid sizing (km scale), as the area to be modelled is on the scale of continental margins. We solve this problem by implementing the governing processes as sub-grid scale routines into the large-scale basin-filling model. This parameterization greatly refines morphodynamic behaviour and the resulting stratigraphy. SimClast recreates realistic geomorphological and stratigraphic delta behaviour in river and wave-dominated settings.GeotechnologyCivil Engineering and Geoscience
Is there a correlation between TMAO plasma levels and archaea in the gut of patients undergoing hemodialysis?
No full textPatients with chronic kidney disease (CKD) present high plasma levels of trimethylamine N-oxide (TMAO), a uremic toxin produced by gut microbiota associated with atherogenesis. Experimental studies have shown that certain methanogenic archaea members use trimethylamine (TMA), the TMAO precursor in the human gut, to produce methane, suggesting a potential strategy to reduce TMAO levels in patients with CKD. Hence, this study aimed to evaluate the association of Archaea in the gut microbiota and TMAO plasma levels in patients with CKD undergoing hemodialysis. Twenty-five patients were enrolled in the study (15 women, 53 (18) years, BMI, 25.8 (6.75) kg/m2). TMAO plasma levels were evaluated using the HPLC-EM/EM method. Fecal DNA was extracted using a commercial kit. Subsequently, we sequenced the V4 region of the 16S rRNA gene to characterize the microbial composition. NCT04600258 was retrospectively registered in September 2022. According to the reference values in the European Uremic Toxins Work Group (EUTox) database, the patients exhibited high TMAO plasma levels, as expected. The most abundant Archaea members were assigned to the Euryarchaeota phylum, the Methanobacteriaceae family, and the genus Methanobrevibacter. A significant negative correlation between TMAO and Methanobrevibacter was observed. To our knowledge, this study represents the first investigation into the correlation between TMAO levels and the prevalence of Archaea in patients with CKD. Our findings support the archaebiotic hypothesis, suggesting that specific members of the archaea community could play a crucial role in reducing TMA production in the human gut, potentially decreasing TMAO synthesis in CKD patients.The authors would like to thank all the patients who participated in the study and the clinic staf. This work was supported by Conselho Nacional de Desenvolvimento Científco e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) support Denise Mafra research. ASR and JS were supported by a KAUST grant (BAS/1/1096-01-01)
Impact of Curcuma longa L. extract supplementation on the gut microbiota of hemodialysis patients
No full textAbstract Introduction: The impact of curcumin on the gut microbiota of chronic kidney disease (CKD) patients is not well known. The aim of this study was to evaluate the effect of Curcuma longa L. on the gut microbiota of CKD patients undergoing hemodialysis (HD). Methods: This was a secondary analysis of data from a randomized, double-blind, placebo-controlled trial. Patients received 100 mL of orange juice, 12 grams of carrot, and 2.5 grams of Curcuma longa L. three times a week after the HD session (Curcuma group) or the same juice without added curcumin (control group) for 12 weeks. The fecal microbiota composition was estimated using short-read sequencing of the V4 region of the 16S rRNA gene on the Illumina platform. Results: Eleven patients participated in this study, five in the curcumin group (66.7% male, 59 ± 16.7 years old, HD vintage of 97 ± 62.6 months, BMI 25.3 ± 2.9 kg/m2) and six in the control group (60% male, 57.5 ± 12.5 years old, HD vintage of 48.3 ± 32.2 months, BMI 25.2 ± 3.1 kg/m2). Supplementation with Curcuma longa L. extract did not modify alpha biodiversity or the taxonomic composition of individuals at the phylum, family, and genus levels. Conclusion: Supplementation with 2.5 g of Curcuma longa L. extract three times per week for 12 weeks was inefficient in modulating the gut microbiota of CKD patients undergoing HD. These results should be interpreted taking into account the small sample size, and future studies with larger cohorts are encouraged.<br
