Structural and dielectric properties of CaSnO3-doped Sr2.1Na0.8Nb5O15 ceramics

The crystallographic, microstructural, and dielectric properties of Sr2.1Na0.8-xCaxNb5-xSnxO15 (x = 0.00, 0.01, 0.05, 0.10) polycrystalline ceramics have been studied by X-ray diffraction, scanning electron microscopy, dielectric spectroscopy (DS) and impedance spectroscopy (IS). For x = 0.00, 0.05, and 0.10, samples are single phase with P4bm symmetry at room temperature with x = 0.01 showing a small quantity of secondary phase(s). All compositions show typical ceramic microstructures and d50 grain sizes ranging from 5.1 to 26.6 μm. DS shows a clear trend in the high temperature ferroelectric-paraelectric transition with the Curie temperature, T0, decreasing from ∼ 160 to ∼ 110 °C, and an additional relaxation at approximately 120 °C with increasing CaSnO3. IS reveals all samples have a homogeneous electrical microstructure with predominantly electronic conduction. The activation energy of conduction calculated from Arrhenius plots of the conductivity increases with CaSnO3 content from 1.27 to 1.38 eV likely due to the expansion of the band gap

PRADA – Next Steps

The PRADA (Collaborative Project on Proliferation Resistance: Acquisition/Diversion Pathway Analysis) study was tasked to further develop the INPRO (International Project on Innovative Nuclear Reactors and Fuel Cycles) methodology in the area of assessing proliferation resistance (mitigating proliferation risk). This paper reports on the results. A DUPIC (Direct Use of Spent PWR Fuel In CANDU) fuelled CANDU reactor was used as a test case in order to develop appropriate methods for the identification and analysis of plausible acquisition paths and to determine the multiplicity and robustness of barriers against proliferation. The study resulted in several recommendations: • The proliferation assessment should be performed at three levels: the State level, the INS (Innovative Nuclear Energy System) level, and the facility level. • The robustness of barriers against proliferation depends on the State’s capabilities, and the relevance of each barrier is dependent on assessment level. • The robustness of barriers is not a function of individual barrier characteristics but is an integrated function of all of the barriers, and is measured by determining whether the safeguards goals can be met. • The INPRO assessment methodology requires information regarding proliferation risks derived from quantitative analysis. The PRADA study identified several areas where the INPRO proliferation resistance manual could be expanded and improved: 1) through a better explanation of acceptance limits, 2) through a restructuring of the evaluation tables, and 3) by provision of more explanatory details. An important conclusion was a proposal to form a “GIF (Generation IV International Forum) / INPRO coordinated set of Proliferation Resistance and safeguardability assessment tools”. This set of tools would bring together the complementary strengths of the GIF and INPRO approaches and demonstrate that the two methods can be used in harmony and provide consistent results. The PRADA study also recommended that an expanded test of the methodology be applied inter alia to an open fuel cycle in a State with an emerging nuclear energy system, or to a generic pyroprocessing fuel cycle building on the GIF ESFR (Example Sodium Fast Reactor) evaluation study.JRC.E.9-Nuclear security (Ispra

Proximal Splenic Artery Embolization In Blunt Splenic Trauma

Proximal embolization of the splenic artery (PSAE) has recently been reported for traumatic splenic injury. The suggested mechanism of action entails a decrease in the splenic blood pressure without ischemia due to collateral blood supply. The main complications of selective embolization are continuous bleeding, splenic infarcts and splenic abscesses. The main complications of observation alone are continuous bleeding and formation of splenic pseudoaneurysms. Our aim was to assess the efficacy of PSAE in the cessation of bleeding without formation of pseudoaneurysms, and the outcome of the spleen after such intervention. A prospective observational study of all patients undergoing PSAE for traumatic splenic injury in our institution over a 33-month period. Clinical and Doppler sonographic examinations were performed to assess cessation of bleeding, splenic blood flow, and formation of splenic pseudoaneurysms, infarcts or abscesses. During 33 months, 11 patients with blunt abdominal trauma and tomographic evidence of either high grade or actively bleeding splenic injuries were treated by PSAE. During follow-up, no patient underwent surgery or repeated embolization. Preserved blood flow was found on Doppler sonography in 82% of the patients and no pseudoaneurysms were demonstrated. A perisplenic collection was found in one patient and responded well to percutaneous drainage. Proximal embolization of the splenic artery for severe splenic injury is highly successful in cessation of bleeding while preserving splenic architecture. There were minimal complications in this series demonstrated by clinical and Doppler examinations

Radio galaxies and feedback from AGN jets

We review current understanding of the population of radio galaxies and radio-loud quasars from an observational perspective, focusing on their large-scale structures and dynamics. We discuss the physical conditions in radio galaxies, their fuelling and accretion modes, host galaxies and large-scale environments, and the role(s) they play as engines of feedback in the process of galaxy evolution. Finally we briefly summarise other astrophysical uses of radio galaxy populations, including the study of cosmic magnetism and cosmological applications, and discuss future prospects for advancing our understanding of the physics and feedback behaviour of radio galaxies