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  • 1
    Language: English
    In: Superconductor science & technology, 2019-08-02, Vol.32 (9), p.94007
    Description: The use of practical high temperature superconductors (HTS), REBCO tapes especially, in magnet applications has become possible thanks to the increasing interest of manufacturers. One difficulty has been the nonlinear material properties that are challenging to measure and model. To advance in such, demo systems are needed and they must be thoroughly analyzed. Recently, one of the first HTS dipole magnets was built to study the usability of REBCO Roebel cables in particle accelerator magnets. The prototype magnet Feather-M2 was designed, constructed and tested within EUCARD2 collaboration project at CERN in 2017. In the measurements, the magnet behaved in an unexpected way: the magnet was able to be operated at operation currents above the maximum current that was predicted based on short-sample measurements. Additionally, unexpectedly gradual dependency between magnet's resistive voltage and operation current was observed. In this work, a thermodynamical model is formulated in order to study the behavior of Feather-M2. The model was parametrized and the parameters were solved via inverse problem by finding the best match to experimental results. Thereby insight was gained on the prospects of the utilized thermodynamical model and also on the behavior and operation conditions of the magnet via the inverse problem solutions. To summarize, this paper presents a new methodology for analyzing magnets in operation and applies it to a state-of-the-art magnet.
    Subject(s): thermal stability ; optimization ; HTS magnets ; modelling
    ISSN: 0953-2048
    E-ISSN: 1361-6668
    Source: IOPscience extra
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  • 2
    Language: English
    In: IEEE transactions on applied superconductivity, 2016-06, Vol.26 (4), p.1-6
    Description: With the Large Hadron Collider (LHC) up and running, studies have started for its successor. Under study is the Future Circular Collider (FCC), which has a circumference of about 100 km, aiming at a proton-proton collision energy of 100 TeV. Consequently, the main bending dipole magnets have to operate at a magnetic field of 16 T. As a first step towards its realization, this paper presents the results of a parametric study of the cross-sectional layout for dipole magnets with a field in the range of 13-17 T using Nb-Ti and Nb 3 Sn superconductors. The principal layouts included are the classical Cosine-Theta, the Canted Cosine-Theta, and the Block type. Conductor cost can be reduced significantly when a graded hybrid solution is chosen. Optimizing such complex magnet layouts requires an iterative algorithm, which arranges the positions of the various blocks of coil windings in the coil cross section, thereby finding the thickness of the coil layers. The iterative algorithm is coupled to an adiabatic quench model, which finds an optimal copper-to-superconductor fraction for each of the layers. Outside the iterative cycle, a pattern search algorithm is applied to find a cost optimal distribution of the magnetic field generated by each coil layer.
    Subject(s): Niobium-tin ; Superconducting magnets ; Conductors ; Future Circular Collider ; Optimization ; Niobium-Titanium ; tri-Niobium Tin ; Layout ; High Magnetic Field ; Accelerator Magnet ; Low Temperature Superconductor ; Iterative algorithms ; Magnetic fields ; Grading ; Condensed Matter Physics ; Electrical and Electronic Engineering ; Electronic, Optical and Magnetic Materials
    ISSN: 1051-8223
    E-ISSN: 1558-2515
    Source: IEEE Electronic Library (IEL)
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  • 3
    Language: English
    In: Superconductor science & technology, 2018-04-25, Vol.31 (6), p.65002
    Description: This paper describes the standalone magnet cold testing of the high temperature superconducting (HTS) magnet Feather-M2.1-2. This magnet was constructed within the European funded FP7-EUCARD2 collaboration to test a Roebel type HTS cable, and is one of the first high temperature superconducting dipole magnets in the world. The magnet was operated in forced flow helium gas with temperatures ranging between 5 and 85 K. During the tests a magnetic dipole field of 3.1 T was reached inside the aperture at a current of 6.5 kA and a temperature of 5.7 K. These values are in agreement with the self-field critical current of the used SuperOx cable assembled with Sunam tapes (low-performance batch), thereby confirming that no degradation occurred during winding, impregnation, assembly and cool-down of the magnet. The magnet was quenched many tens of times by ramping over the critical current and no degradation nor training was evident. During the tests the voltage over the coil was monitored in the microvolt range. An inductive cancellation wire was used to remove the inductive component, thereby significantly reducing noise levels. Close to the quench current, drift was detected both in temperature and voltage over the coil. This drifting happens in a time scale of minutes and is a clear indication that the magnet has reached its limit. All quenches happened approximately at the same average electric field and thus none of the quenches occurred unexpectedly.
    Subject(s): high temperature superconductors ; cold testing ; superconducting accelerator magnets ; superconducting magnets ; Condensed Matter Physics ; Materials Chemistry ; Electrical and Electronic Engineering ; Superconducting magnets ; High temperature superconductors ; Metals and Alloys ; Ceramics and Composites ; Superconducting accelerator magnets ; Cold testing
    ISSN: 0953-2048
    E-ISSN: 1361-6668
    Source: IOPscience extra
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  • 4
    Language: English
    In: IEEE transactions on applied superconductivity, 2018-04, Vol.28 (3), p.1-10
    Description: The EuCARD2 collaboration aims at the development of a 10 kA-class superconducting, high current density cable suitable for accelerator magnets, to be tested in small coils and magnets capable to deliver 3-5 T when energized in stand-alone mode, and 15-18 T when inserted in a 12-13 T background magnet. REBCO tape, assembled in a Roebel cable, was selected as conductor. The developed REBCO tape has reached a record engineering critical current density, at 4.2 K and 18 T of 956 A/mm 2 . Roebel cable carried up to 13 kA at 20 K when tested in a small coil (FeatherM0.4). Then a first dipole magnet, wound with two low-grade Roebel cables of 25 m each, was assembled and tested. The dipole reached the short sample critical current of 6 kA generating more than 3 T central field at about 5.7 K, with indications of good current transfer among cable strands and of relatively soft transition. The construction of a costheta dipole is also discussed. Eucard2 is reaching its objective and is continuing with the H2020-ARIES program aiming at doubling the Je at 20 T to obtain 6 T as standalone and 18 T as insert in a high field facility.
    Subject(s): Coils ; High-temperature superconductors ; accelerator magnets ; Critical current density (superconductivity) ; Collaboration ; HTS dipoles ; Superconducting magnets ; Conductors ; HTS conductor ; Condensed Matter Physics ; Electrical and Electronic Engineering ; Electronic, Optical and Magnetic Materials
    ISSN: 1051-8223
    E-ISSN: 1558-2515
    Source: IEEE Electronic Library (IEL)
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  • 5
    Language: English
    In: Development (Cambridge), 2013-06, Vol.140 (11), p.2365-2376
    Description: In development, lymphatic endothelial cells originate within veins and differentiate via a process requiring Prox1. Notch signaling regulates cell-fate decisions, and expression studies suggested that Jag1/Notch1 signaling functions in veins during lymphatic endothelial specification. Using an inducible lymphatic endothelial Prox1CreER(T2) driver, Notch signaling was suppressed by deleting Notch1 or expressing dominant-negative Mastermind-like in Prox1+ endothelial cells. Either loss of Notch1 or reduced Notch signaling increased Prox1+ lymphatic endothelial progenitor cell numbers in the veins, leading to incomplete separation of venous and lymphatic vessels. Notch loss of function resulted in excessive Prox1+ lymphatic cells emerging from the cardinal vein and significant lymphatic overgrowth. Moreover, loss of one allele of Notch1 in Prox1 heterozygous mice rescued embryonic lethality due to Prox1 haploinsufficiency and significantly increased Prox1+ lymphatic endothelial progenitor cell numbers. Expression of a constitutively active Notch1 protein in Prox1+ cells suppressed endothelial Prox1 from E9.75 to E13.5, resulting in misspecified lymphatic endothelial cells based upon reduced expression of podoplanin, LYVE1 and VEGFR3. Notch activation resulted in the appearance of blood endothelial cells in peripheral lymphatic vessels. Activation of Notch signaling in the venous endothelium at E10.5 did not arterialize the cardinal vein, suggesting that Notch can no longer promote arterialization in the cardinal vein during this developmental stage. We report a novel role for Notch1 in limiting the number of lymphatic endothelial cells that differentiate from the veins to assure proper lymphatic specification.
    Subject(s): Tumor Suppressor Proteins - metabolism ; Membrane Glycoproteins - metabolism ; Signal Transduction ; Endothelial Cells - metabolism ; Homeodomain Proteins - metabolism ; Humans ; Cells, Cultured ; Glycoproteins - metabolism ; Male ; Mice, Transgenic ; Receptor, Notch1 - metabolism ; Vascular Endothelial Growth Factor Receptor-3 - metabolism ; Microcirculation ; Animals ; Time Factors ; Gene Expression Regulation, Developmental ; Alleles ; Female ; Heterozygote ; Cell Differentiation ; Mice ; Index Medicus ; Prox1 ; Lymphatic endothelial cells ; Mouse ; Notch1
    ISSN: 0950-1991
    E-ISSN: 1477-9129
    Source: HighWire Press (Free Journals)
    Source: Company of Biologists
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 6
    Language: English
    In: Nature cell biology, 2011-09-11, Vol.13 (10), p.1202-1213
    Description: Angiogenesis, the growth of new blood vessels, involves specification of endothelial cells to tip cells and stalk cells, which is controlled by Notch signalling, whereas vascular endothelial growth factor receptor (VEGFR)-2 and VEGFR-3 have been implicated in angiogenic sprouting. Surprisingly, we found that endothelial deletion of Vegfr3, but not VEGFR-3-blocking antibodies, postnatally led to excessive angiogenic sprouting and branching, and decreased the level of Notch signalling, indicating that VEGFR-3 possesses passive and active signalling modalities. Furthermore, macrophages expressing the VEGFR-3 and VEGFR-2 ligand VEGF-C localized to vessel branch points, and Vegfc heterozygous mice exhibited inefficient angiogenesis characterized by decreased vascular branching. FoxC2 is a known regulator of Notch ligand and target gene expression, and Foxc2(+/-);Vegfr3(+/-) compound heterozygosity recapitulated homozygous loss of Vegfr3. These results indicate that macrophage-derived VEGF-C activates VEGFR-3 in tip cells to reinforce Notch signalling, which contributes to the phenotypic conversion of endothelial cells at fusion points of vessel sprouts.
    Subject(s): Neovascularization, Physiologic - drug effects ; Human Umbilical Vein Endothelial Cells - metabolism ; Receptors, Notch - metabolism ; Humans ; Vascular Endothelial Growth Factor A - metabolism ; Vascular Endothelial Growth Factor A - genetics ; Receptors, Notch - antagonists & inhibitors ; Transfection ; RNA Interference ; Time Factors ; Forkhead Transcription Factors - metabolism ; Vascular Endothelial Growth Factor D - genetics ; Phosphatidylinositol 3-Kinase - metabolism ; Vascular Endothelial Growth Factor Receptor-3 - deficiency ; Transduction, Genetic ; Retinal Vessels - metabolism ; Endothelial Cells - metabolism ; Rhombencephalon - blood supply ; Gene Expression Regulation ; Vascular Endothelial Growth Factor Receptor-3 - metabolism ; Forkhead Transcription Factors - genetics ; Vascular Endothelial Growth Factor C - genetics ; Mice, Knockout ; Antibodies - pharmacology ; Macrophages - metabolism ; Vascular Endothelial Growth Factor D - metabolism ; Animals ; Signal Transduction - drug effects ; Vascular Endothelial Growth Factor B - metabolism ; Vascular Endothelial Growth Factor C - metabolism ; Cell Line, Tumor ; Neovascularization, Pathologic - genetics ; Vascular Endothelial Growth Factor B - genetics ; Mice ; Neovascularization, Pathologic - metabolism ; Protein Kinase Inhibitors - pharmacology ; Vascular Endothelial Growth Factor Receptor-3 - genetics ; Endothelial Cells - drug effects ; Physiological aspects ; Blood vessels ; Cellular signal transduction ; Growth factor receptors ; Research ; Vascular endothelial growth factor ; Index Medicus ; Medicin och hälsovetenskap
    ISSN: 1465-7392
    ISSN: 1476-4679
    E-ISSN: 1476-4679
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 7
    Language: English
    In: Development (Cambridge), 2014-06, Vol.141 (12), p.2446-2451
    Description: Collecting lymphatic ducts contain intraluminal valves that prevent backflow. In mice, lymphatic valve morphogenesis begins at embryonic day 15.5 (E15.5). In the mesentery, Prox1 expression is high in valve-forming lymphatic endothelial cells, whereas cells of the lymphatic ducts express lower levels of Prox1. Integrin α9, fibronectin EIIIA, Foxc2, calcineurin and the gap junction protein Cx37 are required for lymphatic valve formation. We show that Notch1 is expressed throughout the developing mesenteric lymphatic vessels at E16.5, and that, by E18.5, Notch1 expression becomes highly enriched in the lymphatic valve endothelial cells. Using a Notch reporter mouse, Notch activity was detected in lymphatic valves at E17.5 and E18.5. The role of Notch in lymphatic valve morphogenesis was studied using a conditional lymphatic endothelial cell driver either to delete Notch1 or to express a dominant-negative Mastermind-like (DNMAML) transgene. Deletion of Notch1 led to an expansion of Prox1(high) cells, a defect in Prox1(high) cell reorientation and a decrease in integrin α9 expression at sites of valve formation. Expression of DNMAML, which blocks all Notch signaling, resulted in a more severe phenotype characterized by a decrease in valves, failure of Prox1(high) cells to cluster, and rounding of the nuclei and decreased fibronectin-EIIIA expression in the Prox1(high) cells found at valve sites. In human dermal lymphatic endothelial cells, activation of Notch1 or Notch4 induced integrin α9, fibronectin EIIIA and Cx37 expression. We conclude that Notch signaling is required for proper lymphatic valve formation and regulates integrin α9 and fibronectin EIIIA expression during valve morphogenesis.
    Subject(s): Lymphatic Vessels - embryology ; Dermis - metabolism ; Signal Transduction ; Humans ; Cells, Cultured ; Receptors, Notch - physiology ; Mice, Transgenic ; Gene Expression Profiling ; Integrin alpha Chains - metabolism ; Receptor, Notch1 - metabolism ; Fibronectins - metabolism ; Connexins - metabolism ; Cell Lineage ; Lymphatic Vessels - metabolism ; Animals ; Genes, Dominant ; Gene Expression Regulation, Developmental ; Gene Deletion ; Proto-Oncogene Proteins - physiology ; Mice ; Transgenes ; Receptor, Notch1 - physiology ; Receptor, Notch4 ; Index Medicus ; Integrin α9 ; Mouse ; Research Reports ; Notch ; Lymphatic valve morphogenesis
    ISSN: 0950-1991
    E-ISSN: 1477-9129
    Source: HighWire Press (Free Journals)
    Source: Company of Biologists
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 8
    Language: English
    In: Biomacromolecules, 2018-07-09, Vol.19 (7), p.2795-2804
    Description: We show that composite hydrogels comprising methyl cellulose (MC) and cellulose nanocrystal (CNC) colloidal rods display a reversible and enhanced rheological storage modulus and optical birefringence upon heating, i.e., inverse thermoreversibility. Dynamic rheology, quantitative polarized optical microscopy, isothermal titration calorimetry (ITC), circular dichroism (CD), and scanning and transmission electron microscopy (SEM and TEM) were used for characterization. The concentration of CNCs in aqueous media was varied up to 3.5 wt % (i.e, keeping the concentration below the critical aq concentration) while maintaining the MC aq concentration at 1.0 wt %. At 20 °C, MC/CNC underwent gelation upon passing the CNC concentration of 1.5 wt %. At this point, the storage modulus (G′) reached a plateau, and the birefringence underwent a stepwise increase, thus suggesting a percolative phenomenon. The storage modulus (G′) of the composite gels was an order of magnitude higher at 60 °C compared to that at 20 °C. ITC results suggested that, at 60 °C, the CNC rods were entropically driven to interact with MC chains, which according to recent studies collapse at this temperature into ring-like, colloidal-scale persistent fibrils with hollow cross-sections. Consequently, the tendency of the MC to form more persistent aggregates promotes the interactions between the CNC chiral aggregates towards enhanced storage modulus and birefringence. At room temperature, ITC shows enthalpic binding between CNCs and MC with the latter comprising aqueous, molecularly dispersed polymer chains that lead to looser and less birefringent material. TEM, SEM, and CD indicate CNC chiral fragments within a MC/CNC composite gel. Thus, MC/CNC hybrid networks offer materials with tunable rheological properties and access to liquid crystalline properties at low CNC concentrations.
    Subject(s): Elasticity ; Methylcellulose - chemistry ; Birefringence ; Nanoparticles - chemistry ; Hydrogels - chemistry ; Index Medicus
    ISSN: 1525-7797
    E-ISSN: 1526-4602
    Source: Hellenic Academic Libraries Link
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 9
    Language: English
    In: Chemical engineering research & design, 2019-06, Vol.146, p.518-527
    Description: [Display omitted] •Models (1D, 3D CFD) were prepared for the extraction of levulinic acid.•The models fit the experimental extraction column data with an excellent accuracy.•The models proved to be a very valuable tool for scale-up and design purposes. 1D axial dispersion and 3D CFD models for the extraction of levulinic acid from dilute aqueous solution by applying 2-methyltetrahydrofuran as a solvent are presented. The models are validated by comparison with the measured levulinic acid concentration profile data obtained in a bench-scale Kühni column. The 1D model contains NRTL parameters for the system levulinic acid-water-2MTHF. Correlations for drop size and hold-up for Kühni columns were taken from literature. The values for overall mass transfer coefficient ranged from 1.4E-5 to 2.2E-5 ms−1, and increased as a function of the rotor speed. The fitting of the column performance resulted in a very good prediction of the solute concentration profiles in the extraction column, and the average absolute value of relative error for the 1D model was 23%. CFD model visualized the column performance at the column height of 150.5–160 cm giving valuable information on back mixing, phase velocities, dispersed phase volume fraction, and mass transfer. Dispersed phase volume fraction and mass transfer contours revealed, that the mass transfer rate (app. 0.25 g L−1s−1) is at its highest just below the rotor, and that there are blind spots in the compartments close to the extractor and just above each down comer. Values for the dispersed phase volume fraction are highest in the same area where the mass transfer reaches the highest values. The highest slip velocity values (app. 0.03 m−1) are located in the tip of each compartment partition plates. General correlations, such as hold-up and drop size correlations, can successfully be applied in levulinic acid-water-2MTHF system reported in this work. The 1D axial dispersion model proved to be valuable tool for scale-up purposes, and CFD model, despite the long time needed for each simulation, gave useful information for the design purposes.
    Subject(s): CFD ; Back-mixing model ; Kühni-column ; Levulinic acid ; Modeling ; 2-methyltetrahydrofuran
    ISSN: 0263-8762
    Source: Academic Search Ultimate
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  • 10
    Language: English
    In: IEEE transactions on applied superconductivity, 2018-04, Vol.28 (3), p.1-5
    Description: The large hadron collider (LHC) upgrade, called high-luminosity LHC is planned for the next decade. A wide range of magnets and new technologies are currently under development. One of these systems will be a set of twin aperture beam orbit correctors positioned on the approaches to the ATLAS and CMS experiments. This twin aperture magnet system comprising 16 magnets, approximately 2 m long, with large 105-mm clear aperture coils. Each aperture will independently deliver 5-T·m integral field, between apertures the field vectors are rotated by 90° from each other, and individually powered. This paper presents the sequence of component developments to produce a cost-effective canted cosine theta model magnet. We describe the challenges encountered during the manufacture of the coil formers with their helical canted coil winding process which places a number of insulated wires into the 2-mm-wide 5-mm-deep slot. We describe the: pressurized impregnation process, multiple jointing to connect inner and outer sets of wires within the confines of the coil assembly, and magnet assembly into support structure and yoke. Finally, we present the quench performance and initial test results of this novel coil configuration.
    Subject(s): Coils ; Insulation ; Large Hadron Collider ; accelerators magnets ; Wires ; Windings ; canted cosine theta (C.C.T.) ; Superconducting magnets ; Apertures
    ISSN: 1051-8223
    E-ISSN: 1558-2515
    Source: IEEE Electronic Library (IEL)
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