Partitioning of PCBs from air to clothing materials in a Danish apartment

Polychlorinated biphenyl (PCB) contamination of buildings continues to pose an exposure threat, even decades after their application in the form of calks and other building materials. In this research, we investigate the ability of clothing to sorb PCBs from contaminated air and thereby influence exposure. The equilibrium concentration of PCB‐28 and PCB‐52 was quantified for nine used clothing fabrics exposed for 56 days to air in a Danish apartment contaminated with PCBs. Fabric materials included pure materials such as cotton and polyester, or blends of polyester, cotton, viscose/rayon, and/or elastane. Air concentrations were fairly stable over the experimental period, with PCB‐28 ranging from 350 to 430 ng/m³ and PCB‐52 ranging from 460 to 550 ng/m³. Mass accumulated in fabric ranged from below detection limits to 4.5 mg/g of fabric. Cotton or materials containing elastane sorbed more than polyester materials on a mass basis. Mass‐normalized partition coefficients above detection limits ranged from 10^5.7 to 10^7.0 L/kg. Clothing acts as a reservoir for PCBs that extends dermal exposure, even when outside or in uncontaminated buildings.     

The validation and further development of a multidimensional cognitive load scale for virtual environments

Measuring cognitive load is important in virtual learning environments (VLE). Thus, valid and reliable measures of cognitive load are important to support instructional design in VLE. Through three studies, we investigated the validity and reliability of Leppink's Cognitive Load Scale (CLS) and developed the extraneous cognitive load (EL) dimension into three sub-scales relevant for VLE: EL instructions, EL interaction, and EL environment. We investigated the validity of the measures using the Partial Credit Model (PCM), Confirmatory Factor Analysis (CFA), and correlations with retention tests. Study 1 (n = 73) investigated the adapted version of the CLS. Study 2 describes the development and validation of the Multidimensional Cognitive Load Scale for Virtual Environments (MCLSVE), with 140 students in higher education. Study 3 tested the generalizability of the results with 121 higher education students in a more complicated VLE. The results provide initial evidence for the validity and reliability of the MCLSVE.     

Focusing on business projects as an area for future research: An exploratory discussion of four different perspectives

An important development in project management in recent years has been the emergence of a new class of projects, in areas such as organisational change and IT, integrated business solutions, and long-term public service delivery. Often referred to as ‘business projects’, this new class of projects (and programmes) reflects a growing conceptual shift away from the traditional engineering view of projects, towards a more business-oriented view, in which the primary concern is no longer the capital asset, system or facility etc, but increasingly the challenge of implementing business strategy, improving organisational effectiveness, and managing the realisation of stakeholder benefits. Drawing on recent research from the UK Government-funded Rethinking Project Management Network, this paper argues that future research in this area needs to look beyond the mainstream literature on project management, to other relevant disciplines such as strategic management, operations management, and the management of change. Against this background, the authors present four conceptual perspectives from the management literature, which can be usefully applied to business projects. They represent exploratory contributions from four participants in the Network – a special collaboration between researchers – whose ideas and perspectives were either discussed at the Network meetings, or are the subject of research elsewhere. Collectively, the four contributions represent an exploratory discussion of different theoretical perspectives, in order to inform and stimulate other researchers and practitioners working in the field.     

Bacterial communities in commercial aircraft high‐efficiency particulate air (HEPA) filters assessed by PhyloChip analysis

Abstract  Air travel can rapidly transport infectious diseases globally. To facilitate the design of biosensors for infectious organisms in commercial aircraft, we characterized bacterial diversity in aircraft air. Samples from 61 aircraft high‐efficiency particulate air (HEPA) filters were analyzed with a custom microarray of 16S rRNA gene sequences (PhyloChip), representing bacterial lineages. A total of 606 subfamilies from 41 phyla were detected. The most abundant bacterial subfamilies included bacteria associated with humans, especially skin, gastrointestinal and respiratory tracts, and with water and soil habitats. Operational taxonomic units that contain important human pathogens as well as their close, more benign relatives were detected. When compared to 43 samples of urban outdoor air, aircraft samples differed in composition, with higher relative abundance of Firmicutes and Gammaproteobacteria lineages in aircraft samples, and higher relative abundance of Actinobacteria and Betaproteobacteria lineages in outdoor air samples. In addition, aircraft and outdoor air samples differed in the incidence of taxa containing human pathogens. Overall, these results demonstrate that HEPA filter samples can be used to deeply characterize bacterial diversity in aircraft air and suggest that the presence of close relatives of certain pathogens must be taken into account in probe design for aircraft biosensors.

Practical Implications

A biosensor that could be deployed in commercial aircraft would be required to function at an extremely low false alarm rate, making an understanding of microbial background important. This study reveals a diverse bacterial background present on aircraft, including bacteria closely related to pathogens of public health concern. Furthermore, this aircraft background is different from outdoor air, suggesting different probes may be needed to detect airborne contaminants to achieve minimal false alarm rates. This study also indicates that aircraft HEPA filters could be used with other molecular techniques to further characterize background bacteria and in investigations in the wake of a disease outbreak.

     

Concentrations and patterns of organochlorine contaminants in white whales (Delphinapterus leucas) from Svalbard, Norway

Blubber was collected from live-captured, adult male white whales (Delphinapterus leucas) from Svalbard, Norway, and analysed for levels and patterns of organochlorine (OC) contaminants. The OC compounds analysed were HCB, dieldrin, sigmaHCH (alpha-HCH, beta-HCH and gamma-HCH), sigmaChl (heptachlor epoxide, oxychlordane, cis-chlordane, trans-nonachlor, and cis-nonachlor), sigmaDDT (pp'-DDT, pp'-DDE and pp'-DDD) and sigmaPCB (27 PCB congeners). The major OC compounds detected in the blubber were sigmaPCB (5103+/-1874 ng/g l.w.) and sigmaDDT (5108+/-1089 ng/g l.w.), which made up 70% of the sigmaOC. These compounds were followed in prevalence by sigmaChl (2872+/-1177 ng/g l.w.), which contributed 20% of the sigmaOC burden. SigmaHCH, HCB and dieldrin were present, but at low concentrations. This OC pattern is typical of top predators in Arctic marine food chains. OC levels in white whales from Svalbard are lower than white whales from the St Lawrence River in Canada and are generally similar to values reported previously for other Arctic white whale stocks. Some geographic patterns in relative prevalence of various OC compounds appear to be quite consistent among various marine mammal species in the Arctic. PCB and DDT concentrations in Svalbard's white whales are below the levels that are thought to have negative effects on reproduction or the immune system.     

Reductive Amination Without the Aldehyde: Use of a Ketolactol as an Aldehyde Surrogate

To overcome stability issues associated with the use of an aldehyde in a catalytic reductive amination reaction, a cyclic ketolactol (ω-hydroxylactone) was employed as an aldehyde surrogate to form a γ-aminoacid. The reaction proceeded most favorably over a Pt/C catalyst. The thermodynamics of each step were evaluated using density functional theory calculations, which correctly predicted the dominance of the ring-closed lactol reactant, yet suggested a preference for a ring-opened iminium intermediate upon the initial, slightly endoergic addition of amine substrate. Exoergic hydrogenation of this intermediate provided the thermodynamic driving force for the overall transformation. During development, the reaction was observed to depend significantly on the volumetric gas to liquid mass transfer coefficient (k_La) and this parameter was optimized to ensure successful scale up in a 400 L stirred tank reactor.     

EEM fluorescence spectroscopy as a fast method to assess the brine composition of salted herring

Ripening of barrel-salted herring (Clupea harengus) is evaluated by the use of fluorescence spectroscopy and protein determinations. During ripening, protein degradation takes place in the herring and protein is extracted into the brine. The present study aims at identifying parameters which are correlated to the ripening characteristics of barrel-salted herring and which can provide a better understanding of the ripening process. Front face fluorescence landscapes were obtained by measuring directly on the brine from barrel-salted herring. These data were analyzed by parallel factor analysis (PARAFAC), which revealed four fluorophores, tryptophan (two states), vitamin B6 and riboflavin. All four parameters showed an increase in concentration during the storage period corresponding to an increase in protein content that varied from 3 g/100 g at day 60 to 5 g/100 g after 277 days of storage. It was not possible to see a difference in the development of the four fluorophores during the ripening period. The protein content was predicted from the fluorescence landscapes by partial least squares (PLS). The use of unfolded fluorescence spectra gave an RMSECV of 0.26 g/100 g and a correlation between the measured protein content and the predicted values of 0.86.     

The effect of external flow on the feeding currents of sessile microorganisms

Microscopic sessile suspension feeders live attached to surfaces and, by consuming bacteria-sized prey and by being consumed, they form an important part of aquatic ecosystems. Their environmental impact is mediated by their feeding rate, which depends on a self-generated feeding current. The feeding rate has been hypothesized to be limited by recirculating eddies that cause the organisms to feed from water that is depleted of food particles. However, those results considered organisms in still water, while ambient flow is often present in their natural habitats. We show, using a point-force model, that even very slow ambient flow, with speed several orders of magnitude less than that of the self-generated feeding current, is sufficient to disrupt the eddies around perpendicular suspension feeders, providing a constant supply of food-rich water. However, the feeding rate decreases in external flow at a range of non-perpendicular orientations due to the formation of recirculation structures not seen in still water. We quantify the feeding flow and observe such recirculation experimentally for the suspension feeder Vorticella convallaria in external flows typical of streams and rivers.