Levels of hexabromocyclododecane in harbor porpoises and common dolphins from western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome p450

Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which gamma-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (sigma)-HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 microg (g of lipid)(-1)) and the northwest coast of Scotland (median concentration 5.1 microg (g of lipid)(-1)). The median levels in other areas were, for the harbor porpoise south coast of Ireland, 1.2 microg (g of lipid)(-1), for the coasts of The Netherlands, Belgium, and France north of Calais (southern North Sea), 1.1 microg (g of lipid)(-1), for the east coast of Scotland (northern North Sea), 0.77 microg (g of lipid)(-1), and, for Galicia (Spain), 0.1 microg (g of lipid)(-1). The median levels for the common dolphin were, for west coast of Ireland, 0.9 microg (g of lipid)(-1), for the French coast of the English Channel between Normandy and Brest, 0.4 microg (g of lipid)(-1), and, for Galicia, 0.2 microg (g of lipid)(-1). A subset of 10 harbor porpoise and 9 common dolphin blubber samples representing all areas were analyzed by LC/MS to determine the diastereomeric composition of their HBCD residues. All samples showed exclusively the peak of alpha-HBCD. To test if biotransformation by the cytochrome P450 system could explain the observed compositional difference with technical HBCD mixtures, a number of in vitro assays with microsomal preparations of liver were carried out. We had to revert to material stored at -80 degrees C from laboratory rats and a fresh harbor seal found dead in the Dutch Wadden Sea, since such liver samples of cetaceans were not in our possession. The in vitro assays showed that beta- and gamma-HBCDs were indeed significantly metabolized when incubated in the presence of NADPH as electron donor, compared to a set of reference samples which were identical except for the addition of NADPH. In contrast, the peak of alpha-HBCD did not decrease significantly in the presence of NADPH. In separate microsomal assays with beta- and gamma-HBCDs, new peaks of brominated compounds (signal at m/z = 79 or 81) with masses of [M + 0] were formed only when NADPH was added. This confirms the process of cytochrome P450 mediated biotransformation. Although rat and harbor seal belong to different families of the mammalia than the cetaceans, we propose that biotransformation by the cytochrome P450 system is also the most likely process to explain the exclusive accumulation of alpha-HBCD in harbor porpoise and common dolphin.     

Multiparameter Analysis of Cooling Efficiency of Ventilated Fruit Cartons using CFD: Impact of Vent Hole Design and Internal Packaging

Forced-air cooling (FAC) efficiency of fruit packed in ventilated cartons can be considerably improved by revising vent hole design and tailoring these openings according to the internal packaging used. Current vent hole designs for fruit cartons, however, often result from trials and errors or are developed in order to improve a specific package functionality, such as fruit cooling rate. This study presents a novel multiparameter evaluation process for ventilated fruit packaging. This multi-parameter strategy evaluates cooling rate and cooling uniformity, airflow resistance and energy efficiency. Computational fluid dynamics is used to evaluate the impact of internal trays and four vent hole designs. One of the designs investigated is currently used in commercial export of apples, while the other three are new configurations proposed to improve fruit cooling efficiency. Results showed that the addition of trays to the existing commercially used Standard Vent hole design increased ventilation energy consumption by 31 % compared to cartons without trays, but in the two newly proposed carton designs (Altvent and Multivent), the energy usage was reduced by 27 and 26 %, respectively, as airflow was distributed more evenly between the five fruit layers. The use of the new vent hole designs (Altvent and Multivent) compared to the Standard Vent design, also considerably improved cooling uniformity and energy efficiency during FAC, reducing cooling heterogeneity by 79 and 51 %, as well as energy consumption by 48 and 7 %, when packed with and without trays, respectively. By simultaneous evaluation of multiple parameters, this analysis approach thus unveiled the benefits and disadvantages of the new ventilated carton designs and can be used to further improve vent hole designs for specific cold chains.     

Tripartite modular multiplication

This paper presents a new modular multiplication algorithm that allows one to implement modular multiplications efficiently. It proposes a systematic approach for maximizing a level of parallelism when performing a modular multiplication. The proposed algorithm effectively integrates three different existing algorithms, a classical modular multiplication based on Barrett reduction, the modular multiplication with Montgomery reduction and the Karatsuba multiplication algorithms in order to reduce the computational complexity and increase the potential of parallel processing. The algorithm is suitable for both hardware implementations and software implementations in a multiprocessor environment. To show the effectiveness of the proposed algorithm, we implement several hardware modular multipliers and compare the area and performance results. We show that a modular multiplier using the proposed algorithm achieves a higher speed comparing to the modular multipliers based on the previously proposed algorithms.     

An exploration of possible design options for a binding energy savings target in Europe

As Europe is not on track in meeting its 2020 energy savings target, there has been quite some debate to make the energy savings target binding instead of indicative. Although the final draft text of the Energy Efficiency Directive left the option of a binding target explicitly open for the period beyond 2014, this statement has watered down in the adopted Directive: If still not on track mid-2014, the European Commission will propose “further measures.” In this paper, we argue that a binding energy savings target could be the first EU legal initiative to look beyond 2020 serving as a beacon for other policies such as for renewables and greenhouse gases that need redefinition after 2020. We therefore explore four possible design options of a binding savings target and assess their feasibility. We conclude that a binding target at Member State level (opposed to an EU-wide target like for the EU Emission Trading System (ETS)) is the most feasible. A binding target at Member State level would ensure political accountability and commitment to deliver results while providing flexibility to choose and apply the most suitable tools to achieve the target. It could provide a framework to guide ambitious and coherent implementation of EU energy efficiency policies, as well as the strengthening of national policies. Furthermore, binding targets at Member State level will make Member States take an ambitious position in Brussels when new energy or CO₂ performance standards for appliances and transport modes are to be set. A Member State binding target applied to end-users (excluding ETS companies) is a design option that covers the vast majority of the cost-effective energy savings potential, maintains the flexibility for ETS companies, and supports the most cost-effective achievement of a greater share of renewables.     

Ozone oxidation for the alleviation of membrane fouling by natural organic matter: A review

Membrane fouling by natural organic matter is one of the main problems that slow down the application of membrane technology in water treatment. O₃ is able to efficiently change the physico-chemical characteristics of natural organic matter in order to reduce membrane fouling. This paper presents the state-of-the-art knowledge of the reaction mechanisms between natural organic matter and molecular O₃ or OH radicals, together with an in-depth discussion of the interactions between natural organic matter and membranes that govern membrane fouling, inclusive the effect of O₃ oxidation on it.     

Levels of polybrominated diphenyl ether flame retardants in sediment cores from Western Europe

The levels of 14 brominated diphenyl ether (BDE)-congeners in sediment cores from three locations in Western Europe have been determined by GC/MS (negative chemical ionization mode). Sediments from the Drammenfjord (Norway), the western Wadden Sea (The Netherlands), and the freshwater Lake Woserin (Mecklenburg-Vorpommern, Germany) showed a time-dependent pattern in the distribution of BDEs since the beginning of the industrial production of polybrominated diphenyl ether (PBDE) formulations. Two out of three commercially available PBDE formulations could be distinguished. Starting from the beginning of the 1970s, the penta-mix formulation is clearly present, but the deca-mix formulation is only present since the late 1970s. The octa-mix formulation appeared to be still absent in these sediments, as its marker-congener, BDE183, was never detected. In the cores from the western Wadden Sea and Lake Woserin, all TOC-normalized concentrations of the penta-BDE-derived congeners were leveling off in the most recent sediment layers representing 1995 and 1997, whereas those in the Drammenfjord were still increasing in 1999. The levels of BDE209, however, decreased in the most recent layer of all three cores. In Lake Woserin, the concentrations of BDE209 were much less elevated above those of the tri- to hexa-BDEs than in the other the two areas. This might be due to the absence of a significant PBDE input from sources other than the atmosphere to this rural lake. The absence of all PBDE congeners in the older layers of the three sediment cores, as well as in several 100-150-My-old layers from an extremely organic-rich marine sediment from the Kimmeridge clay formation in Dorset (UK), indicated the absence of natural production of the BDE congeners analyzed.     

Simultaneous measurement of oxygen and carbon dioxide diffusivities in pear fruit tissue using optical sensors

Gas diffusion properties of pear tissue are important in relation to gas exchange of the fruit with its environment during storage. In this contribution, a set‐up for measuring tissue diffusivity using fluorescent optical probes was developed. O₂ and CO₂ diffusivities were determined simultaneously based on a finite element model describing simultaneous O₂ and CO₂ gas transport as well as respiration in the tissue. The effect of variations on the diffusion set‐up conditions such as the volume of the measurement chamber and thickness of the sample on the accuracy of the estimated diffusivities was investigated using a sensitivity analysis on simulated data. The optical sensors produced good informative O₂ and CO₂ partial pressure versus time profiles. The average O₂ and CO₂ diffusivity of pear cortex tissue was (2.56 ± 0.48) × 10^?10 m² s^?1 and (3.8 ± 1.1) × 10^?9 m² s^?1, respectively. The coefficient of variation of diffusivity of O₂ and CO₂ in pear tissue due to bias, variation of the sample thickness and volume of the measurement chamber was 2.0–2.3% and 2.1–2.4% for a measurement chamber volume between 7.5 and 15 mL and a tissue thickness of 1–2.5 mm, respectively. The variability of estimated diffusivities due to measurement errors was eight times smaller than the biological variability. Copyright © 2007 Society of Chemical Industry     

Advances in Immobilized Organocatalysts for the Heterogeneous Asymmetric Direct Aldol Reactions

The aim of this article is to collect the results published from the beginning (2000) on asymmetric direct aldol reactions taking place in the presence of immobilized chiral organocatalysts. The seven groups of organocatalysts discussed are: asymmetric direct aldol reactions catalyzed by: (1) covalently bonded immobilized hydroxyproline organocatalysts; (2) covalently bonded immobilized prolinamide organocatalysts; (3) covalently bonded immobilized peptide organocatalysts; (4) other covalently bonded immobilized chiral organocatalysts; (5) chiral organocatalysts bonded by ionic groups; (6) chiral organocatalysts with adsorptive bonding; and (7) other types of immobilized chiral organocatalysts. The main objective of this article based on results obtained by using about 360 immobilized organocatalysts, to bring to the focus of catalyst systems in which the aldol reactions yield beta-hydroxyketones of maximal optical purity, while keeping catalyst concentrations and reaction times as low and as short as possible. Trends recognized in data obtained in this field of investigation may mark out further tasks for the purpose of practical application.     

Separation of Zinc by a Non‐dispersion Solvent Extraction Process in a Hollow Fiber Contactor

Abstract

A process for recovery of zinc from acid solution with di(2‐ethyl hexyl phosphoric acid) (D2EHPA) dissolved in iso‐dodecane was carried out at 20°C in a countercurrent tubular membrane extractor using a hollow fiber as solid support. Experiments were performed at different aqueous metal concentrations (0.1–1.0 g/L), pH 0.1–2.1, and D2EHPA concentrations (2–8 v%). It was found that both the flux of metal and the extraction extent was highly influenced by the extractant concentration and the pH of the feed solution. Overall mass transfer coefficients were determined and related to the tube side, the membrane, and the shell side mass transfer by varying the aqueous flow rate (0.38–0.80 L/min) and organic flow rate (0.22–0.57 L/min) in countercurrent flow. The overall mass transfer coefficient for zinc extraction ranged from 6.2×10^?6 m/s to 25.3×10^?6 m/s. It was concluded that extraction kinetics were a major contributor to the overall resistance to mass transfer.