Prenatal diagnosis of Caudal Regression Syndrome : a case report

BACKGROUND: Caudal regression is a rare syndrome which has a spectrum of congenital malformations ranging from simple anal atresia to absence of sacral, lumbar and possibly lower thoracic vertebrae, to the most severe form which is known as sirenomelia. Maternal diabetes, genetic predisposition and vascular hypoperfusion have been suggested as possible causative factors. CASE PRESENTATION: We report a case of caudal regression syndrome diagnosed in utero at 22 weeks' of gestation. Prenatal ultrasound examination revealed a sudden interruption of the spine and "frog-like" position of lower limbs. Termination of pregnancy and autopsy findings confirmed the diagnosis. CONCLUSION: Prenatal ultrasonographic diagnosis of caudal regression syndrome is possible at 22 weeks' of gestation by ultrasound examination

Limitation of the exponential model for the correction for mass discrimination effects during isotope ratio measurements by MC-ICPMS. Demonstration with Sr at 5-15 microL min-1 continuous liquid flow rates

The need for performing isotope ratio measurements by MC-ICPMS on samples only available in small sizes and not allowing any dilution requires the development of sample introduction systems able to work below 10 μL min-1 (continuous mode). For the torch integrated sample introduction system (TISIS), the optimisation of the conditions involves the study of the temperature of the spray chamber (TSC) and the sample flow rate. This paper investigates the consequences of changing TSC up to 100 oC and the sample flow rate down to 5 μL min-1 on mass discrimination effects. The validity of the exponential model commonly used to correct for these effects was tested for strontium isotopic measurements. Two categories of processes favouring the heaviest isotopes were envisaged: at plasma stage – “mechanism 1”, and within the ion beam – “mechanism 2”. The extraction potential applied inside the interface (HV1) was progressively increased, and results obtained for a range of approximately ± 5-6 V around HV1 = 4004 V at 15 μL min-1 and TSC = 40 ºC were used as reference. The intensity of mass discrimination effects increased at 15 μL min-1 and TSC = 60 or 100 ºC, and decreased at 5 μL min-1 and TSC = 40 ºC. At TSC = 100 ºC (15 μL min-1) or at 5 μL min-1 (TSC = 40 ºC) the stability of mass discrimination effects and the average efficiency of the exponential model were particularly degraded. The contribution of mechanism 1 (and its influence on mechanism 2) seemed to be the determining factor. At TSC = 100 ºC the hypothesis made was the acceleration of the solvent evaporation process inside the TISIS, leading to variations in the characteristics of the tertiary aerosols. And the consequence was an increase of the plasma mass discriminative effects (ion diffusion) reinforced from the extra energy made available to the plasma ions. At 5 μL min-1, changes in the plasma composition arising from the reduction of the water load in combination with the ion production at an earlier stage within the plasma followed by the processes of ion diffusion were also hypothesized as possible causes for the inadequacy of the exponential model.JRC.D.2-Standards for Innovation and sustainable Developmen

Hydrostatic compression behaviour of steel-composite hybrid tubes

International audienceno abstrac

Hydrostatic compression behaviour of steel-composite hybrid tubes

International audienceno abstrac

Neutron capture studies of 206Pb at a cold neutron beam

Gamma-ray transitions following neutron capture in 206Pb have been studied at the cold neutron beam facility of the Budapest Neutron Centre using a metallic sample enriched in 206Pb and a natural lead nitrate powder pellet. The measurements were performed using a coaxial HPGe detector with Compton suppression. The observed gamma-rays have been incorporated into a decay scheme for neutron capture in 206Pb. Partial capture cross sections for 206Pb(n,g) at thermal energy have been derived relative to the cross section for the 1884 keV transition after neutron capture in 14N. From the average crossing sum a total thermal neutron capture cross section of 29+2-1 mb was derived for the 206Pb(n,g) reaction. The thermal neutron capture cross section for 206Pb has been compared with contributions due to both direct capture and distant unbound s-wave resonances. From the same measurements a thermal neutron induced capture cross section of (649 +/- 14) mb was determined for the 207Pb(n,g) reaction.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

MC-ICPMS Isotope Ratio Measurements Using an Ultra-Low Flow Sample Introduction System

This study characterises for the first time isotope ratio measurements by multi-collector ICPMS when performed at liquid flow rates as low as 10-15 µL min-1. An evolution of the torch integrated sample introduction system (TISIS) was employed, which combined an Opalmist nebulizer and a heated single pass spray chamber, allowing the transport of almost 100 % of the solvent. The different factors potentially influencing the isotope ratio measured values and the associated uncertainties (sensitivity and interferences, mass discrimination effects, repeatability of isotope ratio measurement, and rinsing time and memory effects) were investigated systematically under varying experimental conditions. Results showed that the liquid flow rate has a large impact on mass discrimination effects, making the control of this variable critical. From 5 to 30 µL min-1, when using the exponential model, the mass discrimination per mass unit changed from -1.6 to -2.1 and from -1.1 to -1.9, for 88Sr+/86Sr+ and 208Pb+/206Pb+ ratios respectively. Moreover, extrapolations from these results lead to the conclusion that a syringe pump may be required instead of a free aspiration regime to control the liquid flow rate and eliminate the possibility of undesired variations of isotope ratio results (typically, 0.05 per mille error for 1-2 % fluctuations at 10 µL min-1). The validity of the exponential model also depended on the experimental conditions selected. When working at 15 µL min-1 and heating the chamber walls at 60-80 ºC, the performance was as good as it could be with a Micromist/water cooled cinnabar combination operated at 200 µL min-1 (thus, the efficiency was 12 times better for the TISIS). Both systems were compared for the measurement of the Sr isotopic signature in honey samples. Since the TISIS allowed for a pre concentration of samples by a factor 5, the combined uncertainty on results could be improved by 1.6 to 4.4. The main drawback was however the longer rinsing time required to reach a stable background signal (10-12 minutes rather than 4).JRC.DG.D.4-Isotope measurement