Fluidized beds as turbulence promoters in the concentration of food liquids by reverse osmosis

Fluidized beds offer a potential improvement of reverse osmosis processes for food liquids, less fouling of the membrane, and reduced energy consumption. Our experiments were concerned with tubular systems in which fluidized beds of glass, steel, and lead beads were used. Glass beads appeared to be preferable, since they caused little damage to the membrane. Only with the larger glass beads (3 mm) did the membrane skin become corrugated, so that the rejection decreased. The permeate flux for Gouda cheese whey was almost equal to that of an empty tube for which the velocity was about thirty times higher. The erosive action of the glass beads on the fouling layer was partially responsible for this effect. For reverse osmosis of skim milk and potato fruit water the bed did not reduce the fouling layer to a sufficient extent and, therefore, had a lower permeate flux than an empty tube

Natural convection heating of liquids, with reference to sterilization of canned food

In a model system the physical transport phenomena that occur during the sterilization of a canned liquid food were investigated. Flow phenomena and heat transfer were studied experimentally as well as theoretically. Experiments on flow patterns and temperature profiles revealed a boundary layer flow at the vertical sidewall, a stratified core in the upper part of the container and a perfectly mixed, unstratified region in the lower part of the container. A dimensionless correlation for the overall heat transfer coefficient from steam to liquid was determined.From the observed flow patterns and temperature profiles a simplified mathematical model was developed, with which temperature stratification in the liquid during heating could be simulated. The applicability of the simplified model for lethality calculations was briefly examined.Some attention was also paid to the effect of solid particles on heating characteristics of the container contents.Literature on the research of convection heating of liquids in closed containers was reviewed, as well as literature about the influence of temperature stratification on natural convection boundary layer flow

The effects of bottom trawling and primary production on the biological traits composition of benthic assemblages

Although many studies have investigated the effects of disturbance and environmental drivers on marine ecosystems, comparatively few have studied their interactions. Using fuzzy coded biological traits, we compared the functional composition, diversity and evenness of benthic communities in the English Channel and in the Celtic and Irish Seas across interacting gradients of bottom trawling and primary production. Fuzzy correspondence analysis indicated greater similarity in trait composition at sites of high trawling pressure than at those of low trawling. In contrast, the analysis revealed no relationship between trait composition and primary production. Trawling and primary production had no effect on the traits ‘longevity’, ‘sediment position’, or ‘feeding mode’. However, trawling had negative effects on all modalities within the trait ‘living habit’, and these effects were strongest for attached and epifaunal organisms but weakest for burrow- and tube-dwelling species. Trawling also negatively affected most modalities within the trait ‘maximum weight’, with strongest effects for organisms weighing between 10 kg. For the trait ‘bioturbation’, upward conveyors were positively related with primary production, whilst other modalities exhibited no clear pattern. Because trawling affected some traits more than others, community biomass was less evenly distributed across traits in highly trawled areas, which resulted in lower levels of functional diversity and evenness. Overall, the effects of bottom trawling were greater in areas of high primary production

Differences in demersal community structure and biomass size spectra within and outside the Maltese Fishery Management Zone (FMZ)

We examined the protection effect of a long-established fisheries protection zone by studying the demersal communities and the biomass size spectra of specific taxonomic groups. The results and the relevant management implications of the community analysis are discussed within the context of the MEDITS trawl survey program, from which the data was derived. The demersal fishery resources on the muddy bottoms of Maltese trawling grounds were found to be stratified in four main depth ranges: 83 to 166 m (outer continental shelf), 140 to 230 m (shelf break), 270 to 440 m (shallow slope), and 466 to 701 m (deep slope). Significant differences were detected between the inside and outside zones of the outer continental shelf. Stations from this stratum inside the protected zone had twice as much biomass as those outside as well as larger individuals of some species (e.g. elasmobranchs). The depth strata identified do not coincide with those sampled in existing trawl survey programmes in the Sicilian Channel, which were set up without reference to demersal assemblage structure and its relation to depth. It is therefore clear that characterisation of the biotic assemblages is important in order to obtain a better sampling representation of each depth-stratum/assemblage type, and this should be considered in the survey design.peer-reviewe

Accurate measurements of small currents using a CCC with DC SQUID read out

The continuous miniaturisation in the semiconductor industry increases the importance of accurate measurement and control of very small currents. In the field of precision electrical measurements, cryogenic current comparators (CCCs) are used as extremely sensitive and accurate instruments for scaling currents. In an international co-operation project, a special CCC system is being developed, optimised for the measurement of extremely small currents to less than 1 pA (10−12 A). DC superconducting quantum interference device (SQUID) readout is used for monitoring the ampere-turn unbalance of the CCC. In this paper, we report on the accurate determination of the CCC and SQUID input coil inductances. Matching of these inductances is required for obtaining ultimate current resolution with the CCC. We find very good agreement between measurements of the CCC inductance at room temperature and at 4.2 K, and results from numerical calculations. The measured values for the input and mutual inductance of the SQUID sensor are in good agreement with the design values when the effect of the slit in the SQUID washer is correctly taken into account. Final current resolution of our measurement system is expected to be better than 1×10−15 A/√Hz for a CCC with 20,000 primary windings

Combined measurements of prey availability explain habitat selection in foraging seabirds

Understanding links between habitat characteristics and foraging efficiency helps predict how environmental changes influence populations of top predators. This study examines whether measurements of prey (clupeids) availability varied over stratification gradients, and determined if any of those measurements coincided with aggregations of foraging seabirds (common guillemot Uria aalge and Manx shearwater Puffinus puffinus) in the Celtic Sea, UK. The probability of encountering foraging seabirds was highest around fronts between mixed and stratified water. Prey were denser and shallower in mixed water, whilst encounters with prey were most frequent in stratified water. Therefore, no single measurement of increased prey availability coincided with the location of fronts. However, when considered in combination, overall prey availability was highest in these areas. These results show that top predators may select foraging habitats by trading-off several measurements of prey availability. By showing that top predators select areas where prey switch between behaviours, these results also identify a mechanism that could explain the wider importance of edge habitats for these taxa. As offshore developments (e.g. marine renewable energy installations) change patterns of stratification, their construction may have consequences on the foraging efficiency of seabirds

Quickscan hoogwaardige toepassingen voor bijproducten uit de voedings- en genotmiddelenindustrie

Deze quickscan heeft tot doel inzicht verschaffen in de mogelijkheden om op kortere en middellange termijn te komen tot alternatieve non-food toepassingen van bijproducten uit de voedings- en genotmiddelenindustrie die nu voornamelijk in de diervoederindustrie worden gebruikt. Er wordt daarvoor een inventarisatie gemaakt van relatief hoogwaardige toepassingen waarvoor het 'proof-of-principle' van de onderliggende technologie inmiddels geleverd i

Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance

Bottom trawling is the most widespread human activity affecting seabed habitats. Here, we collate all available data for experimental and comparative studies of trawling impacts on whole communities of seabed macroinvertebrates on sedimentary habitats and develop widely applicable methods to estimate depletion and recovery rates of biota after trawling. Depletion of biota and trawl penetration into the seabed are highly correlated. Otter trawls caused the least depletion, removing 6% of biota per pass and penetrating the seabed on average down to 2.4 cm, whereas hydraulic dredges caused the most depletion, removing 41% of biota and penetrating the seabed on average 16.1 cm. Median recovery times posttrawling (from 50 to 95% of unimpacted biomass) ranged between 1.9 and 6.4 y. By accounting for the effects of penetration depth, environmental variation, and uncertainty, the models explained much of the variability of depletion and recovery estimates from single studies. Coupled with large-scale, high-resolution maps of trawling frequency and habitat, our estimates of depletion and recovery rates enable the assessment of trawling impacts on unprecedented spatial scales

Stable isotope signatures reveal small-scale spatial separation in populations of European sea bass

Scientific information about European sea bass (Dicentrarchus labrax) stocks in NE Atlantic is limited and a more accurate definition of the stock boundaries in the area is required to improve assessment and management advice. Here we study the connectivity and movement patterns of European sea bass in Wales (UK) using the stable isotope (δ13C and δ15N) composition of their scales. Analysis of fish scale δ13C and δ15N values in the last growing season was performed on 189 adult sea bass caught at nine coastal feeding grounds. Fish >50 cm total length (TL) caught in estuaries had very low δ13C and this is characteristic of fresh water (organic/soil) input, indicating the primary use of estuaries as feeding areas. A random forest classification model was used to test if there was a difference in δ15N and δ13C values between north, mid and south Wales and whether it was possible to correctly assign the fish to the area where it was caught. This analysis was restricted to fish of a similar size range (40-50 cm TL) caught in open coastal areas (n=156). The random forest classification model showed that about 75% of the fish could be correctly assigned to their collection region based on their isotope composition. The majority of the misclassifications of fish were fish from north Wales classifying to mid Wales and vice versa, while the majority of fish from south Wales were correctly assigned (80%). Our findings suggest that two sub-populations of sea bass in Welsh waters use separate feeding grounds (south vs. mid/north Wales), and may need separate management