Portable Systems for Metered Dispensing of Aggressive Liquids.

Precise metering in liquid dispensing applications often requires application-specific solutions due to incompatibilities of the sensor and actuator components with the dispensed liquids. Some reoccurring challenges are aggressive liquids that would damage the sensors or tubing, the need for sterile liquids while the pumps or sensors cannot be sterilized, or media that can clog the sensor channels. Two different dispensing systems are here presented where the dispensing flow rate or volume is indirectly measured through a coupled pressure change or airflow, thus avoiding contact between the sensor and liquid. The controlled pressure-driven dispensing (cPDD) system builds an overpressure in the liquid reservoir by pumping air and controls the opening of the liquid output valve based on the internal pressure development. The FlowCap system uses a liquid pump on the outlet, controlled by the measured inflow of air to the reservoir. Both systems are designed for compactness and portability and offer independent operation, as well as control and communication, over a wireless interface.

Validation of Flow Cytometry and Magnetic Bead-Based Methods to Enrich CNS Single Cell Suspensions for Quiescent Microglia.

Microglia are resident mononuclear phagocytes within the CNS parenchyma that intimately interact with neurons and astrocytes to remodel synapses and extracellular matrix. We briefly review studies elucidating the molecular pathways that underlie microglial surveillance, activation, chemotaxis, and phagocytosis; we additionally place these studies in a clinical context. We describe and validate an inexpensive and simple approach to obtain enriched single cell suspensions of quiescent parenchymal and perivascular microglia from the mouse cerebellum and hypothalamus. Following preparation of regional CNS single cell suspensions, we remove myelin debris, and then perform two serial enrichment steps for cells expressing surface CD11b. Myelin depletion and CD11b enrichment are both accomplished using antigen-specific magnetic beads in an automated cell separation system. Flow cytometry of the resultant suspensions shows a significant enrichment for CD11b(+)/CD45(+) cells (perivascular microglia) and CD11b(+)/CD45(-) cells (parenchymal microglia) compared to starting suspensions. Of note, cells from these enriched suspensions minimally express Aif1 (aka Iba1), suggesting that the enrichment process does not evoke significant microglial activation. However, these cells readily respond to a functional challenge (LPS) with significant changes in the expression of molecules specifically associated with microglia. We conclude that methods employing a combination of magnetic-bead based sorting and flow cytometry produce suspensions highly enriched for microglia that are appropriate for a variety of molecular and cellular assays.

Building materials as a source of PCB pollution in Bergen, Norway.

Although PCB is a globally recognised pollutant, an understanding of its transport from man-made building materials to the environment is poorly constrained. This paper presents data from a study that was conducted in order to determine the extent of PCB usage in plaster on building façades in the Bergen area, Norway. The study was to determine whether PCB concentrations vary according to building usage type and age. One aim was also to determine the nature and extent of displacement of PCB from the façade into the surrounding soil. Buildings built between 1952 and 1979 were chosen for the study. Three different media were sampled during the study; surface soil, plaster and paint. Samples were then analysed for PCB7 content. The results show that there is a difference in PCB usage in buildings of different age and usage type. Residential buildings and schools demonstrated higher PCB concentrations in both soil and plaster than buildings designated for office use, storage, or for industrial purposes. Buildings erected in the 1950s and 1960s also show a higher PCB concentration than buildings from a later date. It appears that the usage of PCB for these purposes decreased in the 1970s. Thirty percent of the soil samples showed a higher PCB concentration than the Norwegian action level. The soil samples tend to have a higher concentration than the corresponding plaster from the adjacent wall, which probably has its cause in the high soil organic matter contents that retains PCB. Plaster has not been considered a pollution source in previous studies; therefore this study demonstrates a new source that needs to be considered in emission calculations.

Critical remarks on the use of terrestrial moss (Hylocomium splendens and Pleurozium schreberi) for monitoring of airborne pollution.

Duplicate samples of the two terrestrial moss species Hylocomium splendens and Pleurozium schreberi, which are widely used to monitor airborne heavy metal pollution, have been collected from eight catchments spread over a 1,500,000 km2 area in northern Europe. These were analysed for a total of 38 elements by inductively coupled plasma-mass spectrometry, inductively coupled plasma-atomic emission spectrometry and cold vapour-atomic absorption spectometry techniques. Results show that the moss species can be combined without interspecies calibration for regional mapping purposes. For the majority of elements the observed within-catchment variation is large--big composite samples over a large area should thus be collected when moss is to be used for monitoring purposes. For the majority of elements the input of dust governs moss chemistry. For a reliable 'contamination' signal over a sizeable area a major source is needed. Some elements show a dependence on climate/vegetation zone. In coastal areas the input of marine aerosols will alter the chemical signal obtained from moss samples.