Spatial diastereomer patterns of hexabromocyclododecane (HBCD) in a Norwegian fjord

Hexabromocyclododecane (HBCD) is the third most used brominated flame retardant globally, and has been found widely distributed in the environment. The present study reports concentrations and spatial patterns of α, β and γ-HBCD in a contaminated Norwegian fjord. Intertidal surface sediment and selected species from the marine food web were sampled at five locations in increasing distance from a known point source of HBCD. All sediment and biota samples were analyzed for the three HBCD diastereomers by liquid chromatography and mass spectrometry (LC/MS). The results demonstrated a HBCD gradient with decreasing concentrations at increasing distance from the point source in sediment and sedentary species, but less so in the species with large feeding ranges. Mean concentrations of ΣHBCD at the closest/most remote locations relative to the point source were 9000/300 ng g^− 1 TOC in sediment and 150/90 ng g^− 1 lw in the species with largest feeding range (great black-backed gull). The HBCD diastereomer patterns were similar for each of the matrices (sediment, organisms) independent of distance from the source, indicating no difference in environmental partitioning between the diastereomers. However, the concentration ratio of diastereomers in each matrix ranged from 3:1:10 (α:β:γ) in the sediments to 55:1 (α:γ) in the highest trophic level species, suggesting diastereomer-specific bioaccumulation in the organisms.     

Ultrasonic techniques for quality assessment of ITER Divertor plasma facing component

The divertor is one of the most challenging components of ITER machine. Its plasma facing components contain thousands of joints that should be assessed to demonstrate their integrity during the required lifetime. Ultrasonic (US) techniques have been developed to study the capability of defect detection and to control the quality and degradation of these interfaces after the manufacturing process. Three types of joints made of carbon fibre composite to copper alloy, tungsten to copper alloy, and copper-to-copper alloy with two types of configurations have been studied. More than 100 samples representing these configurations and containing implanted flaws of different sizes have been examined.US techniques developed are detailed and results of validation samples examination before and after high heat flux (HHF) tests are presented. The results show that for W monoblocks the US technique is able to detect, locate and size the degradations in the two sample joints; for CFC monoblocks, the US technique is also able to detect, locate and size the calibrated defects in the two joints before the HHF, however after the HHF test the technique is not able to reliably detect defects in the CFC/Cu joint; finally, for the W flat tiles the US technique is able to detect, locate and size the calibrated defects in the two joints before HHF test, nevertheless defect location and sizing are more difficult after the HHF test.     

An assessment of the skid resistance effect on traffic safety under wet-pavement conditions

Pavement-tire friction provides the grip that is required for maintaining vehicle control and for stopping in emergency situations. Statistically significant negative correlations of skid resistance values and wet-pavement accident rates have been found in previous research. Skid resistance measured with SCRIM and crash data from over 1750 km of two-lane rural roads in the Spanish National Road System were analyzed to determine the influence of pavement conditions on safety and to assess the effects of improving pavement friction on safety. Both wet- and dry-pavement crash rates presented a decreasing trend as skid resistance values increased. Thresholds in SCRIM coefficient values associated with significant decreases in wet-pavement crash rates were determined. Pavement friction improvement schemes were found to yield significant reductions in wet-pavement crash rates averaging 68%. The results confirm the importance of maintaining adequate levels of pavement friction to safeguard traffic safety as well as the potential of pavement friction improvement schemes to achieve significant crash reductions.     

Size Effect on Properties of Varistors Made From Zinc Oxide Nanoparticles Through Low Temperature Spark Plasma Sintering

Conditions for the elaboration of nanostructured varistors by spark plasma sintering (SPS) are investigated, using 8‐nm zinc oxide nanoparticles synthesized following an organometallic approach. A binary system constituted of zinc oxide and bismuth oxide nanoparticles is used for this purpose. It is synthesized at room temperature in an organic solution through the hydrolysis of dicyclohexylzinc and bismuth acetate precursors. Sintering of this material is performed by SPS at various temperatures and dwell times. The determination of the microstructure and the chemical composition of the as‐prepared ceramics are based on scanning electron microscopy and X‐ray diffraction analysis. The nonlinear electrical characteristics are evidenced by current–voltage measurements. The breakdown voltage of these nanostructured varistors strongly depends on grain sizes. The results show that nanostructured varistors are obtained by SPS at sintering temperatures ranging from 550 to 600 °C.     

Sustainability metrics for eco-technologies assessment, Part II. Life cycle analysis

This work presents a sustainability analysis of CO₂ reuse to produce dimethyl carbonate (DMC) via ethylene oxide (ROUTE A) and via urea methanolysis (ROUTE B). Two different technologies are considered in ROUTE A: reaction followed by separation and reactive distillation. Life cycle analyses of the ROUTES are presented employing sustainability analysis performed in HYSYS process simulator, along with WAR Algorithm. Process economical optimization is performed to maximize the processes profitability. A sustainability function, defined as a 2D indicator involving both economical and environmental aspects, is calculated for the optimized processes. Additional sustainability indexes are evaluated: material index, energy index, and ecoefficiency. The results, under both economical and environmental aspects, show that ROUTE A is the most sustainable. The study also points to the relevance of the frontier set between the domains cradle-to-gate and gate-to-gate in assessing process sustainability during LCA.     

Can Brazil replace 5% of the 2025 gasoline world demand with ethanol?

Increasing use of petroleum, coupled with concern for global warming, demands the development and institution of CO₂ reducing, non-fossil fuel-based alternative energy-generating strategies. Ethanol is a potential alternative, particularly when produced in a sustainable way as is envisioned for sugarcane in Brazil. We consider the expansion of sugarcane-derived ethanol to displace 5% of projected gasoline use worldwide in 2025. With existing technology, 21 million hectares of land will be required to produce the necessary ethanol. This is less than 7% of current Brazilian agricultural land and equivalent to current soybean land use. New production lands come from pasture made available through improving pasture management in the cattle industry. With the continued introduction of new cane varieties (annual yield increases of about 1.6%) and new ethanol production technologies, namely the hydrolysis of bagasse to sugars for ethanol production and sugarcane trash collection providing renewable process energy production, this could reduce these modest land requirements by 29–38%.     

Influence of water type and maturation time on the properties of kaolinite–saponite peloids

We studied the effects of maturation time and water type on the properties of peloids. The peloids were prepared artificially by mixing the same amount of solid phase of kaolin and bentonite (9:1, m:m) with hypersaline mineral water (sodium potassium chloride water) from a spring in La Malahá (Granada, Spain) and bidistilled water (oligometallic water). The liquid/solid ratio was 2:1, m:m, with periodic manual homogenization and maturation time of one to three months. The water content of the peloids was maintained constant during the entire period of maturation.The peloid properties considered were the composition of the liquid phase, the thermal behaviour, the amount of defects in the structure of the main minerals present in the solid phase (kaolinite and saponite) and the ultramicroscopic fabric of the material, determined by scanning electron microscopy (SEM) and image analysis (IA). To date, the latter aspect has been very little studied.The composition of the liquid phases changed with maturation time. Most of the parameters measured showed a tendency to increase with increasing maturation time, as a consequence of releasing ions from the clay minerals into the liquid phase. Thus, the bidistilled water became mineral water. The initial differences between the two waters employed in the mixture were maintained in the liquid phases.The investigation of the thermal behaviour of the peloid revealed that the decrease in temperature followed, with time, a fitted logarithmic curve where R² > 0.9. The maximum change occurred in the first stage, later cooling being slower. A statistic relationship was found between the cooling kinetic and pore size and the size of the particle aggregates measured by SEM-IA. The peloids cooled more rapidly with increasing maturation time, as in the case of saline water.Both the Hinckley index of kaolinite and Integral Breadth index of saponite changed with the maturation time of the peloid. At the end of the maturation process similar values were reached regardless of the water employed.The main effect of maturation time was the increase in the size of the particle aggregates, the formation of a fabric with a more reticular morphology, and the increase in the area occupied by the pores in the SEM micrographs.     

Structural cast-in-place SFRC: technology,control criteria and recent applications in spain

Steel fiber-reinforced concrete (SFRC) has been traditionally applied to pavements or tunnelling. However, classical structural applications have not been developed so fully. This paper examines different reasons which may justify the lack of this application. Several technologies on the fiber dosing system are presented and assessed. The SFRC reception control and acceptance criteria have been developed in accordance with the upcoming Spanish code. Adopting such criteria is justified on previous experiences and test viability under cast-in-place conditions. Some lines of action to promote the use of fibers with structural purposes are proposed. Two examples of recent applications are also set out, and a justification of the convenience of SFRC in terms of structural evaluation and durability under seawater conditions is provided.     

A comparison of loop closing techniques in monocular SLAM

Loop closure detection systems for monocular SLAM come in three broad categories: (i) map-to-map, (ii) image-to-image and (iii) image-to-map. In this paper, we have chosen an implementation of each and performed experiments allowing the three approaches to be compared. The sequences used include both indoor and outdoor environments and single and multiple loop trajectories.