Pervaporation as an alternative to headspace

The use of pervaporation as an alternative to headspace is proposed. The analytical system involves the speciation of organomercury compounds in solid samples using pervaporation, which has been coupled for the first time to gas chromatography. The speciation of mercury as Me(2)Hg, Et(2)Hg, and MeHgCl has been carried out without any derivatization of the analytes, which, after separation from the solid matrix, are preconcentrated on a Tenax minicolumn prior to desorption and chromatographic separation on a semicapillary column (HP-1) prior to atomic fluorescence detection. No column degradation was observed. Linear ranges and detection limits slightly better than those obtained by headspace GC were observed for mercury species in solid samples. Excellent recoveries (between 95 and 107%) for mercury species added to complex solid samples were obtained by this extremely simple and easily automated setup.     

Young people,disclosure of personal information and online privacy: Control,choice and consequences

This paper examines the privacy implications of the different online practices in which young people disclose personal information, and how associated configurations of choice and control create possibilities for violations of online privacy. The implications of the commercial and non-commercial use of young peoples' personal information are examined, with a specific focus on how this can potentially facilitate cyberbullying. The paper suggests that educational strategies should more clearly focus on encouraging young people to protect their online privacy, encourage control over disclosure practices, and consider the potential commercial and non-commercial uses of their information. There is a need for development of these strategies to be informed by empirical research exploring the everyday contexts and social norms which influence young peoples' online behaviour. Such an evidence-base can inform a critical review of educational, legal and regulatory actions which aim to protect their online privacy and safety.     

The JavaSeal Mobile Agent Kernel

Mobile agents show promise as a new distributed programming paradigm in which locality plays a central role—programs that are able to move closer to their data can overcome limitations of connectivity, latency or bandwidth. Mobility also enables distributed systems to evolve; for instance, the deployment of a new service over a network can be programmed as part of the service itself. Of course, moving programs introduces new challenges. One of these is related to program structure: How much of a computation should be moved? Where are the boundaries between mobile and immobile entities drawn? A second challenge is to provide security guarantees: How can the actions of mobile agent be controlled? And what kinds of security properties can we realistically expect to enforce? We answer these questions within the framework of the JavaSeal mobile agent system kernel. JavaSeal provides several abstractions for constructing agent systems in Java. Our basic building block is the seal which is a nested encapsulated computation fragment with sharply delineated boundaries. Strands are sequential threads of computation bound to a seal. Capsules transfer passive seals and objects over communication channels; Traffic over channels is regulated by portals. We argue that these abstractions are sufficient to program secure mobile agent systems. An electronic commerce application built over our kernel is used as a demonstrator.

     

Quantifying streambank movement and topography using unmanned aircraft system photogrammetry with comparison to terrestrial laser scanning

Streambank movement is an integral part of geomorphic changes along river corridors and affects a range of physical, ecological, and socio‐economic systems including aquatic habitat, water quality, and infrastructure. Various methods have been used to quantify streambank erosion, including bank pins, ground surveys, lidar, and analytical models, however, due to high‐cost or labour intensive fieldwork these are typically feasible or appropriate only for site‐specific studies. Advancements in unmanned aircraft systems (UAS) and photogrammetry provide opportunities for more rapid and economical quantification of streambank erosion and deposition at variable scales. This work assesses the performance of UAS‐based photogrammetry for capturing topography of streambank surfaces and quantifying bank movement. UAS data are compared to terrestrial laser scanner (TLS) and GPS surveying from streambank sites located in Vermont that featured a variety of bank conditions and vegetation. Cross‐sectional analysis of data from UAS and TLS revealed that the UAS reliably captured the bank surface within 0.2 m of TLS and GPS surveys across all sites during leaf‐off conditions. Mean error between UAS and TLS was only 0.11 m in early spring conditions. Dense summer vegetation resulted in decreased accuracy and was a limiting factor in the ability of the UAS to capture the ground surface. At areas with observed bank movement, the change in cross‐sectional area estimated using UAS data compared reliably to TLS survey for net cross‐sectional changes greater than 3.5 m², given a 10% error tolerance. At locations with smaller changes, error increased due to the effect of vegetation, georeferencing, and overhanging bank profiles. UAS‐based photogrammetry shows significant promise for capturing bank topography and movement at fine resolutions in a flexible and efficient manner.     

Identification of estrogenic compounds emitted from the combustion of computer printed circuit boards in electronic waste

Rapid changes in technology have brought about a surge in demand for electronic equipment. Many of these products contain brominated flame-retardants (BFRs) as additives to decrease the rate of combustion, raising concerns about their toxicological risk. In our study, emissions from the combustion of computer-printed circuit boards were evaluated in the T47D-KBluc estrogen-responsive cell line at a series of concentrations. There was significant activity from the emission extract when compared to the positive control, 0.1 nM estradiol. After HPLC fractionation, GC/MS identified ten chemicals which included bisphenol A; the brominated derivates mono-, di-, and tribisphenol, triphenyl phosphate, triphenyl phosphine oxide, 4'-bromo-[1,1'-biphenyl]-4-ol,3,5-dibromo-4-hydroxybiphenyl,3,5-dibromo-2-hydroxybiphenyl, and the oxygenated polyaromatic hydrocarbon benzanthrone. Commercially available samples of these ten compounds were tested. The compound 4'-bromo-[1,1'-biphenyl]-4-ol resulted in dose-dependent significant increases for luciferase activity at concentrations ranging from 0.1 to 10 microM in the T47D-KBluc assay. The chemical also demonstrated an affinity for binding to the estrogen receptor (ER) with an IC50 of 2 x 10(-7) M. To determine the uterotrophic activity, three doses (50, 100, and 200 mg/kg/day) of 4'-bromo-[1,1'-biphenyl]-4-ol were administered to adult ovariectomized Long-Evans rats for 3 days. Treatment of the animals with 200 mg/ kg/day showed an increase in uterine weight Hence one new chemical, released by burning of electrical wastes, was identified which displays estrogenic activity both in vitro and in vivo. However, it was about 1000-fold less potent than ethynyl estradiol.