565 research outputs found
Sponge-associated fungi and their bioactive compounds - the Suberites case
No full textSpecimens of Suberites domuncula that had been cultured in aquaria for 4 weeks were analyzed for their associated fungi. A total of 81 fungal strains belonging to 20 different genera was isolated and identified by morphological and molecular methods. The most frequently isolated taxa were Cladosporium spp., Penicillium spp., Petriella sp., Phialophora spp. and Engyodontium album. Based on chromatographic and mass spectrometric analysis of fungal extracts, as well as on bioassay results, Aspergillus ustus, Penicillium sp., Petriella sp. and Scopulariopsis sp. were selected for in-depth analysis of their natural products. A total of 19 different fungal metabolites, including three new natural products, was isolated and structurally identified. A. ustus yielded two sesquiterpenes, a drimane derivative and deoxyuvidin, as well as a sesterterpene ophiobolin H. The drimane derivative had an ED50 value against L5178Y cells of 1.9 mu g ml(-1) in vitro. The crude extract of Petriella sp. was also strongly cytotoxic against the L5178Y cell line. The cyclic tetrapeptide WF-3161 was primarily responsible for the activity; the ED50 value was <0.1 mu g ml(-1). It was identical to the known compound WF-3161 and had been previously isolated from Petriella guttulata. In addition to WF-3161, three further natural products were obtained and unequivocally identified as new derivatives of infectopyrone by one-and two-dimensional NMR spectroscopy and by mass spectroscopy. Of the new compounds, only dihydroinfectopyrone was active against L5178Y cells; the ED50 value was 0.2 mu g ml(-1). Penicillium sp. yielded the largest number of metabolites. Viridicatin, viridicatol, cyclopenin and cyclopenol suppressed larval growth of the polyphagous pest insect Spodoptera littoralis when incorporated into an artificial diet at an arbitrarily chosen concentration of 237 ppm. Viridicatol was the most active compound and had an ED50 value of ca. 50 ppm. Scopulariopsis sp. yielded three metabolites, including the known acetylcholinesterase inhibitors quinolactacin A1 and A2
MULTIPHOTON DISSOCIATION AND IONIZATION OF Ni(CO), AND VARIOUS COBALT COMPLEXES IN A JET-COOLED MOLECULAR BEAM: COMPARISON WITH MPI OF WF.
No full textAuthor Institution: Department of Chemistry, University of Illinois at ChicagoMutiphoton ionization spectroscopy of Ni(CO), and various cobalt complexes have been investigated. Their MPI spectra exhibited relatively sharp and narrow peaks, namely atomic lines, in the 410-510nm region. Two-photon resonance ionization spectra of metal atoms have been observed in Ni(CO), and cobalt complexes. The multiphoton process for dissociation and ionization in these complexes will be discussed. However, MPI spectra of WF, have exhibited broad bands over the 450-500nm region. The MPI spectra of WF, are quite different than those of Ni(CO), and cobalt complexes: no atomic bands have been observed. The spectra can be instead assigned to three-photon molecular resonance ionization of WF,. All the MPI spectra observed have been assigned and predicted pathways of the MPD/MPI mechanism have been postulated based on energertic thresholds and a power study. Comparison between molecular MPI and atomic MPI in the supersonic jet expansion will be discussed
Tungsten Fibre Reinforced Tungsten (Wf /W) using Yarn Based Textile Preforms
No full textTungsten Fibre Reinforced Tungsten (Wf/W) using Yarn Based Textile PreformsJ.W.Coenena,e,∗,P.Huberb, L.Raumanna, D.Schwalenberga,d, Y.Maoa, J.Rieschc,Ch.Linsmeiera, R.Neuc,da)Forschungszentrum J ̈ulich GmbH, Institut f ̈ur Energie- und Klimaforschung 52425J ̈ulich, Germany,b)Institut f ̈ur Textiltechnik (ITA) der RWTH Aachen University,Aachen, Germany,c)Max-Planck-Institut f ̈ur Plasmaphysik, 85748 Garching,Germany,d)Technische Universit ̈at M ̈unchen, 85748 Garching, Germany,e)Department of Engineering Physics, University of Wisconsin Madison, WI 53706Madison, USAMaterial issues pose a significant challenge for the design of future fusion reactors.Tungsten (W) is the main candidate material as it is resilient against erosion, has thehighest melting point of any metal and shows rather benign transmutations under neu-tron irradiation. However, W is intrinsically brittle and faces operational embrittlement.To overcome these issues new advanced materials are being developed. W-fibre re-inforced W-composite material (Wf/W) incorporates extrinsic toughening mechanismsallowing the redistribution of stress peaks and thus allowing steps towards applica-tion in a future fusion reactor. Recently progress has been made towards fully densemulti short-fibre powder metallurgical production of Wf/W [2] as well as optimising theprocess understanding for the routes using chemical deposition [3].In this contribution the recent status for the Wf/W production will be given with a focuson the introduction of advanced textile preforms produced from W-yarns [1]. In thepast, typically monofilamantes with a diameter of150μm(OSRAM) have been used toweave textile preforms to facilitate large scale production of e.g. for CVD-Wf/W [3].However, the high stiffness of the tungsten fibers with 150 um diameter oftenpresents some challenges, i.e. positioning of a flat preform during the CVD processes.Here less stiff16μmor25μmfibres can be used where the strength of the16μmfibresis at4500MPa[3] and thus significant higher than the strength of the150μmfibre.After the initial success in yarn production [1] a larger amount of yarns were indus-trially produced at Bossert&Kast and used for Weaving. The superior weavability ofthe yarn allows a much more flexible textile preform to be manufactured. Here threetypes of weaves are being compared, firstly of course the original monofilamant basedweave and then the yarn based options utilising first a classical50μmtungsten fila-ment in the weft direction and a second one utilising the identical yarn type in bothwarp and weft direction. Testing of these weaves in the CVD (Wf/W) production isessential to optimise density and fibre volume fraction.For the individual yarns already a dense infiltration is observed and needs nowto be established for the woven product. Modelling shows that utilising a yarn basedweave and thus making the layer placement more accurate, which is crucial to allowWf/W production with optimal density and mechanical properties.[1] Coenen J.W. et al.Physica Scripta, IOP, T171, 014061, (2020).[2] Mao, Y. et al.Composites Part A:,Elsevier BV, 2018, 107, 342-353.[3] Gietl, H. et al.Journal of Composite Materials, (2018), 002199831877114.∗Corresponding Author: tel +492461615536 e-mail [email protected]
Corn-bran: Alternative cellulosic filler for polypropylene
No full textIn this study, the use-ability of corn bran (CB) as a reinforcing filler in polypropylene (PP) matrix was investigated. The properties of CB/PP composites were compared with wood fiber (WF) filled PP composites. In order to enhance the interfacial adhesion, maleated-PP (PP-g-MAH) (MaPP) was used. The CB/PP and WF/PP composites were compounded in an Xplore laboratory compounder. The CB/PP/MaPP and WF/PP/MaPP composites were characterized by tensile test, differential scanning calorimetry (DSC), thennogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The morphology investigated by scanning electron microscopy (SEM). It was shown that corn bran can be an alternative candidate to be used as a reinforcing natural filler source for thermoplastic composites
Long-term warfarin therapy and biomarkers for osteoporosis and atherosclerosis
No full textAbstractBackgroundStroke prevention by warfarin, a vitamin K antagonist, has been an integral part in the management of atrial fibrillation. Vitamin K-dependent matrix Gla protein (MGP) has been known as a potent inhibitor of arterial calcification and osteoporosis. Therefore, we hypothesized that warfarin therapy affects bone mineral metabolism, vascular calcification, and vascular endothelial dysfunction.MethodsWe studied 42 atrial fibrillation patients at high-risk for atherosclerosis having one or more coronary risk factors. Twenty-four patients had been treated with warfarin for at least 12months (WF group), and 18 patients without warfarin (non-WF group). Bone alkaline phosphatase (BAP) and under carboxylated osteocalcin (ucOC) and receptor activator of nuclear factor-kappa B ligand (RANKL) were measured as bone metabolism markers. Reactive hyperemia-peripheral arterial tonometry (RH-PAT) index measured by Endo-PAT2000 was used as an indicator of vascular endothelial function.ResultsThere were no significant differences in patient background characteristics and other clinical indicators between the two groups. In WF group, the ucOC levels were significantly higher than those in the non-WF group (10.3±0.8 vs. 3.4±0.9ng/mL; P<0.01), similarly, the RANKL levels in the WF group were higher than those in the non-WF group (0.60±0.06 vs. 0.37±0.05ng/mL; P=0.007). Moreover, RH-PAT index was significantly lower in the WF group compared to those in the non-WF group (1.48±0.11 vs. 1.88±0.12; P=0.017).ConclusionsLong-term warfarin therapy may be associated with bone mineral loss and vascular calcification in 60–80year old hypertensive patients
Closed-loop model-based wind farm control using FLORIS under time-varying inflow conditions
No full textWind farm (WF) controllers adjust the control settings of individual turbines to enhance the total performance of a wind farm. Most WF controllers proposed in the literature assume a time-invariant inflow, whereas important quantities such as the wind direction and speed continuously change over time in reality. Furthermore, properties of the inflow are often assumed known, which is a fundamentally compromising assumption to make. This paper presents a novel, closed-loop WF controller that continuously estimates the inflow and maximizes the energy yield of the farm through yaw-based wake steering. The controller is tested in a high-fidelity simulation of a 6-turbine wind farm. The WF controller is stress-tested by subjecting it to strongly-time-varying inflow conditions over 5000 s of simulation. A time-averaged improvement in energy yield of 1.4% is achieved compared to a baseline, greedy controller. Moreover, the instantaneous energy gain is up to 11% for wake-loss-heavy situations. Note that this is the first closed-loop and model-based WF controller tested for time-varying inflow conditions (i.e., where the mean wind direction and wind speed change over time) at such fidelity. This solidifies the WF controller as the first realistic closed-loop control solution for yaw-based wake steering.Team Jan-Willem van Wingerde
Adsorption of elemental S and Cs on si (100) 2x1 surfaces, 1995
No full textThis study examined the adsorption of elemental S onclean Si(lOO) surfaces and Cs on s- covered Si(lOO) surfaces. The study was performed in an UHV system using LEED, AES and WF measurements. The objective was the protection of the\ surface against degradation. The s adsorption process may be enhanced by the addition of Cs. Results indicate that S adsortion forms: a hemisulfide, (~0.5 ML) with a (2xl) structure and a monosulfide, (~1 ML) with a (lxl) structure. Adsorption of Cs on clean Si(100)2xl reduces the WF to a minimum value with a subsequent increase towards the value of metallic Cs. Preadsorption of Son Si(100)2xl lowers the WF to a final plateau without the increase. The presence of S increases the binding energy and the maximum amount of Cs that can be deposited on the Si(lOO) surface. Structural models for S and Cs on Si(lOO) surfaces have been given in the text
GPU implementation for spline-based wavefront reconstruction
No full textThis paper presents an adaptation of the distributed-spline-based aberration reconstruction method for Shack–Hartmann (SH) slope measurements to extremely large-scale adaptive optics systems and the execution on graphics processing units (GPUs). The introduction of a hierarchical multi-level scheme for the elimination of piston offsets between the locally computed wavefront (WF) estimates solves the piston error propagation observed for a large number of partitions with the original version. To obtain a fully distributed method for WF correction, the projection of the phase estimates is locally approximated and applied in a distributed fashion, providing stable results for low and medium actuator coupling. An implementation of the method with the parallel computing platform CUDA exploits the inherently distributed nature of the algorithm. With a standard off-the-shelf GPU, the computation of the adaptive optics correction updates is accomplished in under 1 ms for the benchmark case of a 200×200 SH array.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.Team Raf Van de PlasControl & SimulationNumerical Analysi
Efficacy of dual antiplatelet therapy for preventing recurrence of arterial thrombosis in patients with antiphospholipid syndrome
No full textObjective. Warfarin is regarded as the standard treatment for preventing thrombotic events in APS, but the recurrence rate is still high. Dual antiplatelet therapy (DAPT) has been shown to be effective for the prevention of acute coronary syndrome or stroke. The objective of this study was to evaluate the efficacy of DAPT for the prevention of thrombosis recurrence in APS patients with history of arterial thrombosis. Methods. This retrospective cohort study of APS patients was conducted at Hokkaido University Hospital between 1990 and 2016. The secondary prophylactic effects and safety of warfarin monotherapy (Wf), antiplatelet monotherapy (AP), warfarin and antiplatelet combination therapy (Wf + AP) and DAPT were evaluated. The primary endpoints were set as thrombosis-free and adverse events-free survival period. Adverse events were defined as severe bleeding and death. Results. A total of 90 APS patients were enrolled. Thrombotic recurrence was found in 40 patients (35 arterial and 5 venous thromboses) and serious adverse events in 20 patients (9 severe bleeding events and 14 deaths). Kaplan-Meier analysis demonstrated a 10-year recurrence-free survival rate of 62%. The recurrence rate per 100 patient-years was as follows: Wf: 11.6, AP: 5.5, Wf: + AP: 3.7, DAPT: 1.8. We demonstrated that DAPT significantly reduced the rate of recurrence compared with Wf (log-rank P = 0.001). There were no significant differences in the rate of serious adverse events among the groups. Conclusion. DAPT might be considered as an effective and safe option for the prophylaxis of recurrent arterial thrombosis in APS
- …
