907 research outputs found

    The NA62 experiment for the study of kaon rare decays at the CERN Super Proton Synchrotron

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    The NA62 experiment has been designed to measure the branching fraction of the decay K+ Ôćĺ ¤Ç+╬Ż╬Ż with Ôł╝ 10% precision in two years of data taking at the CERN SPS. The branching fraction of this decay is calculated with a precision of few percents within the Standard Model and its measurement can put constraints on new physics scenarios complementary to LHC physics. In this paper, the NA62 experimental layout and the current status of detector construction will be presented

    Sant'Imbenia (Alghero): further archaeometric evidence for an Iron Age market square

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    AbstractLead isotope compositions were determined for 18 metal objects from the archaeological site of Sant'Imbenia, NW Sardinia, dating to the end of the ninth century BCE onwards. The provenance of some objects is unambiguously traced to SW Sardinia; other objects could derive either from central Sardinia or the Iberian coastal ranges. The variety of the provenances attests to a wide trade network that spanned the entire island of Sardinia and extended to the Iberian sites

    Luminescent protein staining with Re(i) tetrazolato complexes

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    Within the general framework of our past and current studies dealing with the investigation of the photophysical properties and the biological behavior of the family of tetrazolato and tetrazole Re(i) complexes, we have endeavored to investigate their potential in the luminescent staining of proteins purified by acrylamide gel electrophoresis. With the aim to provide the first examples of luminescent Re(i) complexes to be exploited for this specific purpose, we have designed and prepared four new Re(i)-based species with the general formula fac-[Re(CO)3(N^N)(Tph)]2-/0, where Tph is the 5-(phenyl)tetrazolato anion and N^N is in turn represented by bathophenanthroline disulfonate (BPS), bathocuproine disulfonate (BCS) or by the SO3-free bathocuproine (BC). In this latter case, the neutral complex fac-[Re(CO)3(BC)(Tph)] served as a model species for the characterization of the former disulfonate complexes. Its cationic analogue fac-[Re(CO)3(BC)(Tph-Me)]+was also prepared by a straightforward methylation reaction. All complexes displayed bright phosphorescence in organic media and, relative to their water solubility, the dianionic species fac-[Re(CO)3(BPS)(Tph)]2-and fac-[Re(CO)3(BCS)(Tph)]2-were also highly emissive in aqueous solution. The sulfonate groups played a key role in promoting and significantly enhancing the luminescent staining performances of both the Re(i) complexes fac-[Re(CO)3(BPS)(Tph)]2-and fac-[Re(CO)3(BCS)(Tph)]2-for proteins. Highlighting a response superior to that of Coomassie Blue and comparable to the one obtained by the well-known silver staining method, these dianionic Re(i)-complexes could efficiently detect up to 50 ng of pure Bovine Serum Albumin (BSA), as well as all proteins found in a Standard Protein Marker mix and from a total protein extract. A lower but still good response for luminescent protein staining was surprisingly obtained by employing the-SO3-free neutral and cationic complexes fac-[Re(CO)3(BC)(Tph)] and fac-[Re(CO)3(BC)(Tph-Me)]+, respectively. These preliminary results open up new possibilities for the further widening of the use of Re(i)-based complexes as luminescent protein staining agents

    Monte Carlo and experimental evaluation of a Timepix4 compact gamma camera for coded aperture nuclear medicine imaging with depth resolution

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    Purpose: We designed a prototype compact gamma camera (MediPROBE4) for nuclear medicine tasks, including radio-guided surgery and sentinel lymph node imaging with a 99mTc radiotracer. We performed Monte Carlo (MC) simulations for image performance assessment, and first spectroscopic imaging tests with a 300┬á╬╝m thick silicon detector. Methods: The hand-held camera (1┬ákg weight) is based on a Timepix4 readout circuit for photon-counting, energy-sensitive, hybrid pixel detectors (24.6┬á├Ś┬á28.2┬ámm2 sensitive area, 55┬á╬╝m pixel pitch), developed by the Medipix4 Collaboration. The camera design adopts a CdTe detector (1 or 2┬ámm thick) bump-bonded to a Timepix4 readout chip and a coded aperture collimator with 0.25┬ámm diameter round holes made of 3D printed 1-mm thick tungsten. Image reconstruction is performed via autocorrelation deconvolution. Results: Geant4 MC simulations showed that, for a 99mTc source in air, at 50┬ámm source-collimator distance, the estimated collimator sensitivity (4┬á├Ś┬á10-4) is 292 times larger than that of a single hole in the mask; the system sensitivity is 0.22 cps/kBq (2┬ámm CdTe); the lateral spatial resolution is 1.7┬ámm FWHM. The estimated axial longitudinal resolution is 8.2┬ámm FWHM at 40┬ámm distance. First experimental tests with a 300┬á╬╝m thick Silicon pixel detector bump-bonded to a Timepix4 chip and a high-resolution coded aperture collimator showed time-over-threshold and time-of-arrival capabilities with 241Am and 133Ba gamma-ray sources. Conclusions: MC simulations and validation lab tests showed the expected performance of the MediPROBE4 compact gamma camera for gamma-ray 3D imaging

    Targeting divalent metal cations with Re(I) tetrazolato complexes

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    ┬ę 2015 The Royal Society of Chemistry. In order to exploit their potential as versatile luminescent sensors, four new Re(i)-tetrazolato complexes with the general formula fac-[Re(CO)3(diim)(L)], where diim is 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen) and L- is either the anion 5-(2'-pyridyl)tetrazolato (2-PTZ-) or 5-(2'-quinolyl)tetrazolato (2-QTZ-), were prepared and fully characterized. In all cases, the regioselective coordination of the Re(i) center through the N2 atom of the tetrazolato ring was observed. This particular feature ensures the availability of the diiminic (N^N) site that was systematically incorporated into the structure of the 2-PTZ- and 2-QTZ- ligands for further coordination with metal cations. Such a diimine-type coordination mode was preliminarily tested by using the mononuclear Re(i) complexes as N^N ligands for the preparation of two [(N^N)Cu(POP)] cationic species, where POP is the chelating diphosphine bis[2-(diphenylphosphino)phenyl]ether. The X-ray structures of the resulting Re(i)-Cu(i) dyads revealed that the Re(i) mononuclear complexes effectively behaved as chelating N^N ligands with respect to the [Cu(POP)]+ fragment, the coordination of which also resulted in significant modification of the Re(i)-centered luminescence. With these data in hand, the luminescent sensing abilities of the four new Re(i) tetrazolato complexes were screened with respect to divalent metal ions of toxicological and biological importance such as Zn(ii), Cd(ii) and Cu(ii). The interaction of the Re(i) complexes with Zn(ii) and Cd(ii) was witnessed by the evident blue shift (??max = 22-36 nm) of the emission maxima, which was also accompanied by a significant elongation of the emission lifetimes. On the contrary, the addition of the cupric ion caused substantial quenching of the radiative processes originating from the Re(i) luminophores

    Muonic atom X-ray spectroscopy for non-destructive analysis of archeological samples

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    The implementation in the RIKEN-RAL negative muons facility of a new muon beamline monitoring and novel digital data acquisition system for gamma and X-ray spectroscopy are presented. This work also shows the high potential of the muonic atoms X-ray spectroscopy technique in non-destructive elemental characterization of archaeological samples

    Experimental Study of Crystal Channelling at CERN-SPS for Beam-Halo Cleaning

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    An efficient and robust collimation system is mandatory for any superconducting hadron collider, in particular for the LHC, which will store a beam of unprecedented high intensity and energy. The usage of highly efficient and short primary bent-crystal collimators might be a possibility for reaching nominal and ultimate LHC intensity. Over the last years, groups in Italy (Ferrara) and Russia (St. Petersburg) have developed crystal production methods, that considerably improve the crystal quality. These developments led, in turn, to a surprising increase in the channeling efficiency and to the recent observation of the ├ó´żťvolume reflection├ó mechanism. The aim of the proposed experiment is the setup of a beam test facility, directing primary protons from the SPS onto a bent silicon crystal, and the quantitative study of single-pass efficiency for all involved processes. Final goal will be the extrapolation of important information on the feasibility of a crystal collimator for halo cleaning in the LHC. The experiment will be performed in the H8 beamline at the CERN SPS where a beam with very small divergence can be provided thus representing a unique facility for tests and characterization of crystals to be used for particle channeling studies

    Pure Red Cell Aplasia (PRCA) and Cerebellar Hypoplasia as Atypical Features of Polyglandular Autoimmune Syndrome Type I (APS-1): Two Sisters With the Same AIRE Mutation but Different Phenotypes

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    The polyglandular autoimmune syndrome type I is a rare hereditary autosomal recessive disease. We describe a child with the classic triad of the disease and her sister with pure red cell aplasia and cerebellar hypoplasia. The latter received two haematopoietic stem cell transplantations, complicated by an acute disseminated encephalomyelitis
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