Mapping the N=40 island of inversion: Precision mass measurements of neutron-rich Fe isotopes

International audienceNuclear properties across the chart of nuclides are key to improving and validating our understanding of the strong interaction in nuclear physics. We present high-precision mass measurements of neutron-rich Fe isotopes performed at the TITAN facility. The multiple-reflection time-of-flight mass spectrometer (MR-ToF-MS), achieving a resolving power greater than 600000 for the first time, enabled the measurement of Fe63–70, including first-time high-precision direct measurements (δm/m≈10−7) of Fe68–70, as well as the discovery of a long-lived isomeric state in Fe69. These measurements are accompanied by both mean-field and ab initio calculations using the most recent realizations which enable theoretical assignment of the spin-parities of the Fe69 ground and isomeric states. Together with mean-field calculations of quadrupole deformation parameters for the Fe isotope chain, these results benchmark a maximum of deformation in the N=40 island of inversion in Fe and shed light on trends in level densities indicated in the newly refined mass surface

Mass Measurements of Neutron-Deficient Yb Isotopes and Nuclear Structure at the Extreme Proton-Rich Side of the N=82 Shell

International audienceHigh-accuracy mass measurements of neutron-deficient Yb isotopes have been performed at TRIUMF using TITAN’s multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). For the first time, an MR-TOF-MS was used on line simultaneously as an isobar separator and as a mass spectrometer, extending the measurements to two isotopes further away from stability than otherwise possible. The ground state masses of Yb150,153 and the excitation energy of Ybm151 were measured for the first time. As a result, the persistence of the N=82 shell with almost unmodified shell gap energies is established up to the proton drip line. Furthermore, the puzzling systematics of the h11/2-excited isomeric states of the N=81 isotones are unraveled using state-of-the-art mean field calculation

Storage of organic and inorganic carbon of biogenic origin in the soils of the parkland-prairie ecosystem

The objective of this study is to estimate the storage of biogenic C in the soils of the Weyburn-Virden map area, a 20,917 km2 parkland-prairie region in southeastern Saskatchewan between 49° and 50° N latitude, and 101\sp\circ15\sp\prime and 104\sp\circ00\sp\prime W longitude. The estimate includes both organic C and previously biogenic C stored in pedogenic carbonates. Quantitative data available on horizons, pedons and landscapes were scaled up to the regional level using soil survey data and maps. A soil organic C distribution map made from 186 catenas over the map area indicates Black soils in the northeastern of the study area have a high organic C storage, in the range of 15 to 24 kg m-2 gradually decreasing through a transitional area to a lower organic C in the range of 6 to 12 kg m-2 in the western part where Dark Brown and Solonetzic soils are dominant. Organic C stores in sandy and Solonetzic soils were less than medium and fine-textured Chernozemic soilsin the same general area. A total of 323 Tg organic C was estimated in soils to a 90-cm depth based on the organic C distribution map. About one third of this C was stored in the Ap horizons. To assess the effects of cultivation on organic C storage, four catenas that included Dark Brown Amulet and Solonetzic Brooking soils were studied. The native catena had a higher organic C store (129 Mg ha-1) compared to the cultivated catenas (114 Mg ha-1 for 90 y, 82 Mg ha-1 for 47 y and 69 Mg ha-1 for 27 y). The high organic C store in the catena with 90 y of cultivation appears to relate with the several periods of forage cropping in the recent past. X-ray diffraction analyses showed that pedogenic carbonates occur mainly as calcite, whereas lithogenic carbonates are mainly dolomite. The \delta\sp{13}3C values of $-$8.2 to $-$5.5% indicate that 70 to nearly 100% of the carbonates in the clay and fine silt fractions of Cca horizons is pedogenic, compared to 7 to 10% in the coarse silts, where the pedogenic carbonates mainly occur as surface coatings. A carbonate distribution map based on the CaCO3 contents of 67 pedons over the map area indicated that carbonate storage in Black soils in the northeast ranged from 330 to 410 kg m-2, compared to 80-250 kg m-2 in Dark Brown and Solonetzic soils of the western regions. (Abstract shortened by UMI.

Condition evaluation of asbestos cement water mains

This paper focuses on the condition evaluation of asbestos cement (AC) pipe samples from three utilities located in different geographic regions and climatic zones in the USA and Canada. Various means of examination or testing were used to evaluate the condition of the samples. These included visual inspection, hardness testing, phenolphthalein testing, crush testing, and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Climate and soil information was also collected for the areas where the three utilities are located to assess the external environments facing the AC pipes. The condition evaluation results were correlated with the external soil characteristics and internal water quality data, collected through a survey, to identify factors contributing to the deterioration of the AC pipes belonging to these utilities. The paper also discusses the variation in the deterioration of the AC water mains from the three utilities.Peer reviewed: NoNRC publication: Ye

Development of an analytical microbial consortia method for enhancing performance monitoring at aerobic wastewater treatment plants

An analytical method to produce profiles of bacterial biomass fatty acid methyl esters (FAME) was developed employing rapid agitation followed by static incubation (RASI) using selective media of wastewater microbial communities. The results were compiled to produce a unique library for comparison and performance analysis at a Wastewater Treatment Plant (WWTP). A total of 146 samples from the aerated WWTP, comprising 73 samples of each secondary and tertiary effluent, were included analyzed. For comparison purposes, all samples were evaluated via a similarity index (SI) with secondary effluents producing an SI of 0.88 with 2.7% variation and tertiary samples producing an SI 0.86 with 5.0% variation. The results also highlighted significant differences between the fatty acid profiles of the tertiary and secondary effluents indicating considerable shifts in the bacterial community profile between these treatment phases. The WWTP performance results using this method were highly replicable and reproducible indicating that the protocol has potential as a performance-monitoring tool for aerated WWTPs. The results quickly and accurately reflect shifts in dominant bacterial communities that result when processes operations and performance change. \ua9 2012 Copyright Taylor and Francis Group, LLC.Peer reviewed: YesNRC publication: Ye

An integrated multi-level watershed-reservoir modeling system for examining hydrological and biogeochemical processes in small prairie watersheds

Eutrophication of small prairie reservoirs presents a major challenge in water quality management and has led to a need for predictive water quality modeling. Studies are lacking in effectively integrating watershed models and reservoir models to explore nutrient dynamics and eutrophication pattern. A water quality model specific to small prairie water bodies is also desired in order to highlight key biogeochemical processes with an acceptable degree of parameterization. This study presents a Multi-level Watershed-Reservoir Modeling System (MWRMS) to simulate hydrological and biogeochemical processes in small prairie watersheds. It integrated a watershed model, a hydrodynamic model and an eutrophication model into a flexible modeling framework. It can comprehensively describe hydrological and biogeochemical processes across different spatial scales and effectively deal with the special drainage structure of small prairie watersheds. As a key component of MWRMS, a three-dimensional Willows Reservoir Eutrophication Model (WREM) is developed to addresses essential biogeochemical processes in prairie reservoirs and to generate 3D distributions of various water quality constituents; with a modest degree of parameterization, WREM is able to meet the limit of data availability that often confronts the modeling practices in small watersheds. MWRMS was applied to the Assiniboia Watershed in southern Saskatchewan, Canada. Extensive efforts of field work and lab analysis were undertaken to support model calibration and validation. MWRMS demonstrated its ability to reproduce the observed watershed water yield, reservoir water levels and temperatures, and concentrations of several water constituents. Results showed that the aquatic systems in the Assiniboia Watershed were nitrogen-limited and sediment flux played a crucial role in reservoir nutrient budget and dynamics. MWRMS can provide a broad context of decision support for water resources management and water quality protection in the prairie region.Peer reviewed: YesNRC publication: Ye

Microplate tectonics: new insights from micro-blocks in the global oceans, continental margins and deep mantle

Any plate has a growth process from small to large. The micro-blocks or micro-plates are sometimes the precursors of large plates. The origin, growth, aborting, extinction and residual process of micro-blocks are of great significance for the study of plate tectonics and pre-plate tectonics. The micro-block can be divided into continental, oceanic and mantle micro-blocks according to their compositions. In this paper, the micro-blocks in the global oceans have been summarized according to the following five environments: mid-ocean ridge system, subduction system, transform fault system, deep-sea intraplate system and extension-rift system. We first propose a genetic classification of micro-blocks comprising: detachment-derived, rifting-derived, transform-derived, propagation-derived, ridge jumping-derived, subduction-derived, accretion-derived, collision-derived and delamination-derived micro-blocks. The different types of micro-block boundaries such as active or fossil detachment fault, subduction zone, mid-ocean ridge, transform fault, fracture zone, transfer fault, accommodation zone, lithosphere-scale strike-slip fault, pseudofault, intra-oceanic convergent zone, overlapping spreading centre, non-transform offset, rheological crustal or mantle discontinuity, are systematically discussed for different micro-blocks. Thus, the number of triple junctions will be more than the 16 in the traditional Plate Tectonic Theory. A stability analysis of these triple junctions is the key to understanding the causes of micro-blocks. However, the micro-block has no ultimate cause, so it is unnecessary to pursue one ultimate cause or initiation of plate tectonics. These micro-blocks within oceanic basins, along oceanic margins or within the deep mantle, can not only be used to develop deep ocean fine structural analysis and plate tectonic reconstruction, but also to explain the causes of micro-blocks in some orogens. This will enrich the research of more detailed pre-orogenic or syn-orogenic evolution of orogenic belts, and even extend to the study of early Precambrian pre-plate tectonic mechanisms. The micro-block can be a transition among microplate, plate and terrane under a plate tectonic regime. It can also be formed in inter-sphere tectonic processes. It helps better our understanding of regimes of cratonic basin formation and intra-continental deformation which are the difficulties faced by the Plate Tectonics Theory. We speculate that the Micro-block Tectonics Theory is a unified tectonic theory of cross-layer, cross-phase, cross-space-time scale and cross-planet