27 research outputs found
Unitarity, Chiral Perturbation Theory, and Meson Form Factors
The inverse-amplitude method is applied to the one-loop chiral expansion of
the pion, kaon, and form factors. Since these form factors are
determined by the same chiral low-energy constants, it is possible to obtain
finite predictions for the inverse-amplitude method. It is shown that this
method clearly improves one-loop chiral perturbation theory, and a very good
agreement between the inverse-amplitude method and the experimental information
is obtained. This suggests that the inverse-amplitude method is a rather
systematic way of improving chiral perturbation theory.Comment: 15 pages, 5 figs, uses REVTeX and epsfig.st
Corrosion Performance of Friction Stir Linear Lap Welded AM60B Joints
A corrosion investigation of friction stir linear lap welded AM60B joints used to fabricate an Mg alloy-intensive automotive front end sub-assembly was performed. The stir zone exhibited a slightly refined grain size and significant break-up and re-distribution of the divorced Mg17Al12 (β-phase) relative to the base material. Exposures in NaCl (aq) environments revealed that the stir zone was more susceptible to localized corrosion than the base material. Scanning vibrating electrode technique measurements revealed differential galvanic activity across the joint. Anodic activity was confined to the stir zone surface and involved initiation and lateral propagation of localized filaments. Cathodic activity was initially confined to the base material surface, but was rapidly modified to include the cathodically-activated corrosion products in the filament wake. Site-specific surface analyses revealed that the corrosion observed across the welded joint was likely linked to variations in Al distribution across the surface film/metal interface
Surface modification processes on European Union bronze reference materials for analytical studies of cultural artefacts
Surface modification processes on European Union bronze reference materials for analytical studies of cultural artefacts
Surface modification processes on European Union bronze reference materials for analytical studies of cultural artefacts
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A supramolecular approach for modulated photoprotection, lysosomal delivery, and photodynamic activity of a photosensitizer
Prompted by a knowledge of the photoprotective mechanism operating in photosystem supercomplexes and bacterial antenna complexes by pigment binding proteins, we have appealed to a boxlike synthetic receptor (ExBox·4Cl) that binds a photosensitizer, 5,15-diphenylporphyrin (DPP), to provide photoprotection by regulating light energy. The hydrophilic ExBox4+ renders DPP soluble in water and modulates the phototoxicity of DPP by trapping it in its cavity and releasing it when required. While trapping removes access to the DPP triplet state, a pH-dependent release of diprotonated DPP (DPPH22+) restores the triplet deactivation pathway, thereby activating its ability to generate reactive oxygen species. We have employed the ExBox4+-bound DPP complex (ExBox4+⊃DPP) for the safe delivery of DPP into the lysosomes of cancer cells, imaging the cells by utilizing the fluorescence of the released DPPH22+ and regulating photodynamic therapy to kill cancer cells with high efficiency
The new Algerian Digital Seismic Network (ADSN): towards an earthquake early-warning system
Seismic monitoring in Algeria has seen great changes since the Boumerdes
earthquake of 21 May 2003. Indeed, the installation of a new digital
seismic network has resulted in a significant upgrade of the previous analog
telemetry network.
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During the last four years, the number of stations in operation has
increased substantially from 25 to 69, and 20 of these are broadband, 2 are
very broadband, 47 are short period. 21 are equipped with accelerometers.
They are all managed by Antelope software from Kinemetrics (US Cie), and
they are all connected in real time and use various modes of transmission
(e.g., satellite, internet, mobile phone). The spatial repartition of the
stations now cover most of northern Algeria. In addition, 70 GPS stations
have recently been added to this seismological network, most of them
collocated with the seismological stations.
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Since the installation of the network, the records of local or distant
events have improved significantly. The automatic processing of the data in a
few minutes allows alert messages to be distributed to Civil Defense and
other national authorities to react promptly to any emergency. The current
strategy is to improve the data quality, to increase the density of the
network by adding about 50 new stations, to reduce the processing time, and
to reduce the time needed to send out an alert message. The result should be
greatly improved network performance, which will lead to an effective
early-warning system