IN-SITU STUDIES OF ELECTROCHEMICAL INTERFACES USING X-RAY RADIATION AT GRAZING ANGLES. APPLICATION TO LIQUID MERCURY

Après un énoncé sommaire des méthodes permettant l'étude in-situ des interfaces électrochimiques au moyen des rayons X, on expose des résultats nouveaux relatifs à la réflexion des rayons X sur la surface du mercure liquide en contact avec sa vapeur ou un gaz inerte et, pour la première fois, en contact avec l'eau ou un électrolyte.After a survey of the in-situ techniques used to probe the structure of electrochemical interfaces, we present new results obtained by specular X-ray reflectivity on the liquid-vapor, the liquid-gas and, for the first time, the liquid-water and liquid-electrolyte interface of mercury

Comparison of air kerma area product and air kerma meter calibrations for X-ray radiation qualities used in diagnostic radiology. Report on the EURAMET project #1177, identified in the BIPM key comparison database (KCDB) as EURAMET RI(I) – S9

Kalibrointilaboratorioiden tarkkuutta ja luotettavuutta testattiin röntgendiagnostiikan annosmittareiden kalibrointiprojektissa EURAMET#1177 (vertailun tunnus EURAMET.RI(I)-S9). Mukana oli 22 eurooppalaista kalibrointilaboratoriota, joiden kalibroitavana kiersi annoksen ja pinta-alan tulon mittareita (DAP, KAP). Vertailu tehtiin vuosien 2011 ja 2012 aikana ja pilottilaboratorio oli kreikkalainen (IRCL/GAEC-EIM). Mittausvertailu oli ensimmäinen laajamittainen kansainvälinen kalibrointivertailu KAP-mittareille. Vertailu toteutettiin yhdessä EURAMET järjestön, IAEA/WHOn laboratorioverkoston ja EURADOS järjestön kanssa. Kaikkiaan 216 suoritetusta KAP mittarin kalibroinnista 176 oli 5% sisällä yhtäpitäviä. Kahdeksalla laboratoriolla tuloksissa oli yli 5% - 45 % ylityksiä vertailuarvosta. Tavanomaisten KAP mittareiden tuloksen riippuvuus röntgenspektristä ja käytetystä annosnopeudesta osoittautui arvioitua suuremmaksi ja myös nämä tekijät vaikuttivat myös joidenkin laboratorioiden tuloksiin. Vertailun tuloksia käytetään varmistamaan kansainvälisen paino- ja mittakomitean hyväksymiä mittaus- ja kalibrointisuoritteita (CIPM-MRA). STUKin kansallinen mittanormaalitoiminta on mukana em. sopimuksessa ja STUKin tulokset kalibrointivertailussa olivat tarkimpien joukossa

Comparison of air kerma area product and air kerma meter calibrations for X-ray radiation qualities used in diagnostic radiology

The EURAMET #1177 project, identified as EURAMET RI(I)-S9 comparison, was the first EURAMET wide scale supplementary comparison in the field of diagnostic radiology for air kerma area product, P-KA, and air kerma, K. It was conducted with the goal of testing the measurement and calibration capabilities for P-KA and K, as well as of supporting the relevant CMCs of the participating laboratories. Two commercial KAP meters and an ionization chamber were selected as transfer instruments and circulated between the 22 European participants. The measurements were performed from April 2011 until July 2012. The stability and the performance of the transfer instruments were tested by the pilot laboratory (IRCL/GAEC-EIM) and few other laboratories as well. The test results revealed that the energy (radiation quality), Q, irradiation area, A, and air kerma rate, K dependences of response of the transfer KAP meters influence the comparison of the results when different measurement conditions were pertained and therefore, appropriate correction factors were obtained and applied to the reported calibration results of the laboratories, when necessary. The comparison reference values (CRVs) for each instrument were determined as the weighted mean of the calibration coefficients of the three participating primary laboratories. The relative standard uncertainty of the CRVs were in the range of (0.4-1.6)% depending on the transfer instruments and beam qualities. The comparison result as the ratio of the corrected calibration coefficient of participant and the respective CRV, and its uncertainty were calculated for all beam qualities and transfer instruments. The informative degrees of equivalence (DoE) were calculated for the refrence RQR 5 beam quality. In case of air kema area product measurements the results for the RADCAL PDC KAP meter were used. The 216 KAP meter calibration results of the two different transfer instruments in terms of air kerma area product were consistent within 5% except 40 results of 8 participants. The 103 air kerma calibration results were consistent within 1.7%, except 10 results of 4 participants

Biomechanical evaluation of the Total Facet Arthroplasty System (R) (TFAS(R)): loading as compared to a rigid posterior instrumentation system

Published online: 10 March 2012PURPOSE: To gain insight into a new technology, a novel facet arthroplasty device (TFAS) was compared to a rigid posterior fixation system (UCR). The axial and bending loads through the implants and at the bone-implant interfaces were evaluated using an ex vivo biomechanical study and matched finite element analysis. Kinematic behaviour has been reported for TFAS, but implant loads have not. Implant loads are important indicators of an implant's performance and safety. The rigid posterior fixation system is used for comparison due to the extensive information available about these systems. METHODS: Unconstrained pure moments were applied to 13 L3-S1 cadaveric spine segments. Specimens were tested intact, following decompression, UCR fixation and TFAS implantation at L4-L5. UCR fixation was via standard pedicle screws and TFAS implantation was via PMMA-cemented transpedicular stems. Three-dimensional 10 Nm moments and a 600 N follower load were applied; L4-L5 disc pressures and implant loads were measured using a pressure sensor and strain gauges, respectively. A finite element model was used to calculate TFAS bone-implant interface loads. RESULTS: UCR experienced greater implant loads in extension (p < 0.004) and lateral bending (p < 0.02). Under flexion, TFAS was subject to greater implant moments (p < 0.04). At the bone-implant interface, flexion resulted in the smallest TFAS (average = 0.20 Nm) but greatest UCR (1.18 Nm) moment and axial rotation resulted in the greatest TFAS (3.10 Nm) and smallest UCR (0.40 Nm) moments. Disc pressures were similar to intact for TFAS but not for UCR (p < 0.04). CONCLUSIONS: These results are most applicable to the immediate post-operative period prior to remodelling of the bone-implant interface since the UCR and TFAS implants are intended for different service lives (UCR--until fusion, TFAS--indefinitely). TFAS reproduced intact-like anterior column load-sharing--as measured by disc pressure. The highest bone-implant moment of 3.1 Nm was measured in TFAS and for the same loading condition the UCR interface moment was considerably lower (0.4 Nm). For other loading conditions, the differences between TFAS and UCR were smaller, with the UCR sometimes having larger values and for others the TFAS was larger. The long-term physiological meaning of these findings is unknown and demonstrates the need for a better understanding of the relationship between spinal arthroplasty devices and the host tissue as development of next generation motion-preserving posterior devices that hope to more accurately replicate the natural functions of the native tissue continues.Simon G. Sjovold, Qingan Zhu, Anton Bowden, Chad R. Larson, Peter M. de Bakker, Marta L. Villarraga, Jorge A. Ochoa, David M. Rosler, Peter A. Cripto