253 research outputs found
X-ray view of steel: A 'living' material that does not easily reveal its secrets
No full textSteel is a difficult material, or rather, it tends to guard its secrets jealously. At the Interfaculty Reactor Institute (iri) and the subfaculty of Materials Science and Engineering at TU Delft, Dr. ir. Erik Offerman is doing his utmost to get to the bottom of this enigma. His endeavours even required the support of the synchrotron of the European Synchrotron Radiation Facility (esrf) at Grenoble in France. Using an X-ray beam from this electron accelerator which is about a billion times as strong as the types used in medical X-ray equipment he managed to become the first person to actually observe the changes in steel as they took place, an achievement that got him into Science magazine. In the mean time, Offerman has developed a model that will enable him to explain the observations made at the synchrotron in Grenoble.Delft University of Technolog
Zinc Reduction/Vaporisation Behaviour from Metallurgical Wastes
No full textThe steelmaking industry produces large quantities of zinc-bearing wastes of varying forms that cannot be treated through integrated steelmaking processes. Simultaneously, by-products of the zinc industry containing great amounts of iron and zinc are stored or landfilled. The amount of zinc in these materials is generally below that which is of value to be recycled directly to the zinc smelter, consequently a method of concentration is required. Tata Steel owns and operates the pilot HIsarna ironmaking plant which, due to its high raw materials flexibility, is attractive for the purpose of processing secondary iron sources. Furthermore, it can facilitate the simultaneous recovery of a zinc-enriched flue dust. The high temperature behaviour of various waste materials will be presented with regards to their recyclability in the HIsarna furnace. Blast furnace (BF) sludge and basic oxygen furnace (BOF) sludge from Tata Steel IJmuiden have been studied along with ‘goethite’ waste produced by Nyrstar. The various input materials have been comprehensively characterised and their reduction/vaporisation behaviour recorded. Mixed samples have been produced and tested in order to define the most appropriate form of delivery of these materials to the HIsarna furnace.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.(OLD) MSE-3(OLD) MSE-
Does Auctioning of Entry Licences Affect Consumers Prices? An Experimental Study
No full textOn an increasing scale auctions are used to allocate the licenses to operate on markets which are thought not suited for free entry.According to standard economic arguments, the license fees paid at the auction will not affect consumer prices since they constitute a sunk cost.This standard view is not uncontested though.In the present paper we experimentally investigate two arguments for a potential upward effect of auctioning of prices: the incorporation of entry fees in prices due to the use of mark-up pricing rules, and the tendency of auctions to select the more collusive firms.Our results indicate that auctioning increases the probability of high prices, and that this is mainly due to the use of mark-up pricing rules.
Lentiviral shRNA delivery reduces apical sodium channel activity in differentiated human airway epithelial cells
No full textBACKGROUND: Epithelial sodium channel (ENaC) hyperactivity has been implicated in the pathogenesis of cystic fibrosis (CF) by dysregulation of fluid and electrolytes in the airways. Here we show proof-of-principle for ENaC inhibition by lentiviral-mediated RNA interference.
METHODS:Immortalized normal (H441) and CF mutant (CFBE) airway cells, and differentiated human bronchial epithelial cells in air liquid interface culture (HBEC-ALI) were transduced with a VSV-G pseudotyped lentiviral (LV) vector expressing a short hairpin RNA (shRNA) targeting the alpha subunit of ENaC (ENaCα), and a marker gene. Efficacy of ENaCα down regulation was assayed by real time PCR, membrane potential assay, western blotting, short-circuit currents, and fluid absorption. Off-target effects were investigated by a lab-on-a-chip QPCR array.
RESULTS:Transduction to near one hundred percent efficiency of H441, CFBE and HBEC-ALI was achieved by addition of the LV vector prior to differentiation and polarization. Transduction resulted in inhibition of ENaCα mRNA and antigen expression, and a proportional decrease in ENaC dependent short circuit current and fluid transport. No effect on transepithelial resistance or cAMP induced secretion responses was observed in HBEC-ALI. Production of interferon alpha and pro-inflammatory cytokine mRNA, indicating TLR3 or RISC mediated off-target effects, were not observed in HBEC-ALI transduced with this vector.
CONCLUSIONS:We have established a generic method to study the effect of RNA interference in HBEC-ALI using standard lentiviral vectors. Downregulation of ENaCα by lentiviral shRNA expression vectors as shown here in the absence of off-target effects has potential therapeutic value in the treatment of cystic fibrosi
Austenite nucleation and growth observed on the level of individual grains by three-dimensional X-ray diffraction microscopy
No full textAustenite nucleation and growth is studied during continuous heating using three-dimensional X-ray diffraction (3-D XRD) microscopy at the European Synchrotron Radiation Facility (ESRF) (Grenoble, France). Unique in-situ observations of austenite nucleation and growth kinetics were made for two commercial medium-carbon low-alloy steels (0.21 and 0.35 wt pct carbon with an initial microstructure of ferrite and pearlite). The measured austenite volume fraction as a function of temperature shows a two-step behavior for both steel grades: it starts with a rather fast pearlite-to-austenite transformation, which is followed by a more gradual ferrite-to-austenite transformation. The austenite nucleus density exhibits similar behavior, with a sharp increase during the first stage of the transformation and a more gradual increase in the nucleus density in the second stage for the 0.21 wt pct carbon alloy. For the 0.35 wt pct carbon alloy, no new nuclei form during the second stage. Three different types of growth of austenite grains in the ferrite/pearlite matrix were observed. The combination of detailed separate observations of both nucleation and growth provides unique quantitative information on the phase transformation kinetics during heating, i.e., austenite formation from ferrite and pearlite.Materials Science and EngineeringMechanical, Maritime and Materials Engineerin
Grain Nucleation and Growth of Individual Austenite and Ferrite Grains Studied by 3DXRD Microscopy at the ESRF
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