Interactions between Silica Particles in the Presence of Multivalent Coions

Forces between charged silica particles in solutions of multivalent coions are measured with colloidal probe technique based on atomic force microscopy. The concentration of 1:z electrolytes is systematically varied to understand the behavior of electrostatic interactions and double-layer properties in these systems. Although the coions are multivalent the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory perfectly describes the measured force profiles. The diffuse-layer potentials and regulation properties are extracted from the forces profiles by using the DLVO theory. The dependencies of the diffuse-layer potential and regulation parameter shift to lower concentration with increasing coion valence when plotted as a function of concentration of 1:z salt. Interestingly, these profiles collapse to a master curve if plotted as a function of monovalent counterion concentration

The Nearshore Fish Fauna of Bonne Bay, a Fjord within Gros Morne National Park, Newfoundland

A standardized survey of the nearshore fish fauna of Bonne Bay, a fjord within Gros Morne National Park in western Newfoundland, was conducted using beach seines, gill-nets and bottom trawls during the month of June over a seven year period (2002- 2008). The survey documents the presence of 31 fish species (in 17 taxonomic families). Sampling sites varied in benthic habitat and associated fish assemblages. Both juvenile and adult life history stages of Atlantic cod (Gadus morhua) were present in Bonne Bay, suggesting the presence of a local population or “bay cod stock”. Acadian redfish (Sebastes fasciatus) live in the bay, and may be members of a genetically differentiable population of redfish. Striped wolfish (Anarhichas lupus), a fish species protected under Canada’s Species at Risk Act (SARA), inhabits Bonne Bay. Surrounded by Gros Morne National Park, this bay with a diverse fish fauna is a focus of local stewardship and conservation efforts

Thermal and pressure stability of myrosinase enzymes from black mustard (Brassica nigra L. W.D.J Koch. var. nigra), brown mustard (Brassica juncea L. Czern. var. juncea) and yellow mustard (Sinapsis alba L. Subsp Maire) seeds

This study investigates the effects of temperature and pressure on inactivation of myrosinase extracted from black, brown and yellow mustard seeds. Brown mustard had higher myrosinase activity (2.75 un/mL) than black (1.50 un/mL) and yellow mustard (0.63 un/mL). The extent of enzyme inactivation increased with pressure (600-800 MPa) and temperature (30-70 °C) for all the mustard seeds. However, at combinations of lower pressures (200-400 MPa) and high temperatures (60-80 °C), there was less inactivation. For example, application of 300 MPa and 70 °C for 10 minutes retained 20%, 80% and 65% activity in yellow, black and brown mustard, respectively, whereas the corresponding activity retentions when applying only heat (70 °C, 10min) were 0%, 59% and 35%. Thus, application of moderate pressures (200-400 MPa) can potentially be used to retain myrosinase activity needed for subsequent glucosinolate hydrolysis

Processes maintaining tropopause sharpness in numerical models

Recent work has shown that the sharpness of the extratropical tropopause declines with lead 15 time in numerical weather prediction models, indicating an imbalance between processes act16 ing to sharpen and smooth the tropopause. In this study the systematic effects of processes 17 contributing to the tropopause sharpness are investigated using daily initialised forecasts 18 run with the Met Office Unified Model over a three-month winter period. Artificial tracers, 19 each forced by the potential vorticity tendency due to a different model process, are used 20 to separate the effects of such processes. The advection scheme is shown to result in an ex21 ponential decay of tropopause sharpness towards a finite value at short lead times with a 22 timescale of 20-24 hours. The systematic effect of non-conservative processes is to sharpen 23 the tropopause, consistent with previous case studies. The decay of tropopause sharpness 24 due to the advection scheme is stronger than the sharpening effect of non-conservative pro25 cesses leading to a systematic decline in tropopause sharpness with forecast lead time. The 26 systematic forecast errors in tropopause-level potential vorticity are comparable to the inte27 grated tendencies of the parametrized physical processes suggesting that the systematic error 28 in tropopause sharpness could be significantly reduced through realistic adjustments to the 29 model parametrization schemes

Systematic model forecast error in Rossby wave structure

Diabatic processes can alter Rossby wave structure; consequently errors arising from model processes propagate downstream. However, the chaotic spread of forecasts from initial condition uncertainty renders it difficult to trace back from root mean square forecast errors to model errors. Here diagnostics unaffected by phase errors are used, enabling investigation of systematic errors in Rossby waves in winter-season forecasts from three operational centers. Tropopause sharpness adjacent to ridges decreases with forecast lead time. It depends strongly on model resolution, even though models are examined on a common grid. Rossby wave amplitude reduces with lead time up to about five days, consistent with under-representation of diabatic modification and transport of air from the lower troposphere into upper-tropospheric ridges, and with too weak humidity gradients across the tropopause. However, amplitude also decreases when resolution is decreased. Further work is necessary to isolate the contribution from errors in the representation of diabatic processes

A Range Extension of the Atlantic Silverside, Menidia menidia, to Coastal Waters of Southwestern Newfoundland

Previous literature documents Atlantic Silverside, Menidia menidia, as occurring from the southern Gulf of St. Lawrence to northeastern Florida. Beach seining in St. George’s Bay, Newfoundland, revealed the presence of this species in coastal waters of southwestern Newfoundland. This is the first documented report of M. menidia in Newfoundland waters. This report extends the range of this species north of the Laurentian Channel, a significant biogeographic barrier to small coastal fishes. All M. menidia collected were young-of-the-year, less than 90 mm SL (Standard Length). These fish may be representative of a larger relict population originating from the Mid-Hypsithermal Interval (7000 years ago) that spawn in St. George’s Bay and migrate offshore for winter. Alternatively, these M. menidia may be survivors of a more southern spawning population carried northward by ocean currents

Fungal Spore Dispersal by the Eastern Box Turtle (Terrapene carolina carolina)

Although spores from most macrofungi are wind- or water-dispersed, dispersal may also occur via biotic vectors. The Eastern box turtle (Terrapene carolina carolina) is a facultative mycovore that may play an important role in fungal spore dispersal although, to date, no information exists on fungi occurring in fecal samples of box turtles or on the ecological significance of box turtles as spore dispersal vectors. Consequently, a study of the potential for Eastern box turtles to act as vectors for spore dispersal was initiated by capturing wild turtles and collecting fecal samples. Serial dilutions from fecal samples were made to enumerate spores, quantify the number of spores per gram of fecal material and to isolate and identify fungi. Fungal spores were found to be extremely abundant throughout all samples. Fecal samples from 36 turtles yielded a total of 23 different fungal taxa in the Zygomycota, Ascomycota and Basidiomycota. Two yeasts that were isolated, Cryptococcus albidus and Rhodotorula mucilaginosa, are reported to naturally occur on Trifolium seeds found in fecal samples. A mold previously unreported from fecal material, Aspergillus wentii, was also found in fecal samples. Data collected suggests Eastern box turtles influence fungal spore dispersal by browsing on plant materials and defecating large numbers of fungal spores within their home ranges

The impact of the skim milk powder manufacturing process on the flavor of model white chocolate

Milk powder is an important ingredient in the confectionary industry but its variable nature has consequences for the quality of the final confectionary product. This paper demonstrates that skim milk powders (SMP) produced using different (but typical) manufacturing processes, when used as ingredients in the manufacture of model white chocolates, had a significant impact on the sensory and volatile profiles of the chocolate. SMP was produced from raw bovine milk using either low or high heat treatment, and a model white chocolate was prepared from each SMP. A directional discrimination test with naïve panellists showed that the chocolate prepared from the high heat SMP had more caramel/fudge character (p<0.0001), and sensory profiling with an expert panel showed an increase in both fudge (p<0.05) and condensed milk (p<0.05) flavor. GC-MS and GC-Olfactometry of both the SMPs and the model chocolates showed a concomitant increase in Maillard-derived volatiles which are likely to account for this change in flavor

Distinguishing the cold conveyor belt and sting jet air streams in an intense extratropical cyclone

Strong winds equatorwards and rearwards of a cyclone core have often been associated with two phenomena, the cold conveyor belt (CCB) jet and sting jets. Here, detailed observations of the mesoscale structure in this region of an intense cyclone are analysed. The {\it in-situ} and dropsonde observations were obtained during two research flights through the cyclone during the DIAMET (DIAbatic influences on Mesoscale structures in ExTratropical storms) field campaign. A numerical weather prediction model is used to link the strong wind regions with three types of ``air streams'', or coherent ensembles of trajectories: two types are identified with the CCB, hooking around the cyclone center, while the third is identified with a sting jet, descending from the cloud head to the west of the cyclone. Chemical tracer observations show for the first time that the CCB and sting jet air streams are distinct air masses even when the associated low-level wind maxima are not spatially distinct. In the model, the CCB experiences slow latent heating through weak resolved ascent and convection, while the sting jet experiences weak cooling associated with microphysics during its subsaturated descent. Diagnosis of mesoscale instabilities in the model shows that the CCB passes through largely stable regions, while the sting jet spends relatively long periods in locations characterized by conditional symmetric instability (CSI). The relation of CSI to the observed mesoscale structure of the bent-back front and its possible role in the cloud banding is discussed