Survey report: Developing methods for abundance estimation of bluefin tuna in Norwegian waters

The major aim of this survey was to map and quantify distribution, school size and behaviour of Atlantic bluefin tuna (Thunnus thynnus) migrating to and feeding in Norwegian waters.The survey covered the region between Bergen and Molde, between 4th to 15th October, onboard hired vessel M. Ytterstad (75 m long) with promising preliminary results for acoustic methods for monitoring the distribution, abundance and behaviour of bluefin tuna in Norwegian waters.publishedVersio

In situ calibration of observatory broadband echosounders

Today, numerous scientific echosounders are used as continuously monitoring systems in ocean observatories. These echosounders are usually calibrated in shallow water, either in laboratory tanks or at random ocean docks before deployments. If the systems are used for quantitative measurements by the observatories, they should be calibrated at the operating depths to consider the environmental effects on the calibration parameters. In this article, a simple in situ calibration method is presented, which was recently applied to one of the nodes of the Norwegian Lofoten-Vesterålen ocean observatory, when the research vessel with dynamic positioning system suspended and moved the calibration sphere between the vessel and the transducer. The calibration results of a 70-kHz split-beam echosounder demonstrate that this method can be applied to the cabled observatories.publishedVersio

Effects of different inlet velocity on the polishing quality of abrasive flow machining

In order to study the effect of different inlet velocity on the polishing quality of abrasive flow machining, this paper takes the variable diameter pipe as an example. The fluid dynamic pressure and total energy of abrasive particles under coupling field with different inlet velocities were carried out by using computational fluid dynamics software. The results of numerical analysis show that the polishing quality becomes better with the increase of the inlet velocity. At the same inlet velocity, the smaller the pipe diameter is, the higher the polishing quality will be. Therefore, the optimum inlet velocity can be selected by numerical simulation according to the size of the aperture of workpiece in the actual processing, which can provide technical support for the production

Testing of trawl-acoustic stock estimation of spawning capelin 2022

This report describes the fourth in a series of trawl-acoustic monitoring surveys of the spawning stock of capelin during the migration to the coast. The survey is a response to a proposal from the industry to evaluate the possibility of using winter monitoring of maturing capelin as an input to the capelin assessment and advice. The timing and geographic coverage of the survey are such that the results would be relevant to use for advice given that the output is reliable. Pre-defined areas off the Troms and Finnmark coast were covered using two vessels, Vendla surveying the eastern part and Eros the western part. A stratified random transect design was originally adopted with two complementary zig-zag grids, the first going in a west-east and the second in an east-west direction over the same strata. However, the high capelin abundances north of Varangerhalvøya lead to changes in the design, and a new stratum with increased effort covering the area with high abundance. The biomass estimate we present is based on the second coverage, but evaluation of the mobility of the fish can be done by comparing the coverages. Echo sounders with frequencies from 18-333 kHz were run together with sonars, and target trawls were carried out on significant pelagic aggregations. Capelin abundance was estimated using 38 kHz data. The median biomass of maturing capelin in the coverage area based on 500 bootstrap runs was estimated at 426 618 tons, with a CV of 42%. The 5% lower and 95% upper confidence limits were 167 555 and 757 229 tons, respectively. The confidence bands overlap with the prediction from the autumn 2021, but the wide confidence interval shows that the survey result is uncertain. The high uncertainty despite the good survey coverage is likely due to the very patchy distribution. Capelin aggregations recorded north of Varanger in the eastern coverage area totally dominated in the estimate. Capelin concentrations were also observed in the west, in areas associated with Fugløybanken and Malangsgrunnen, but the capelin abundance in these areas seemed to decrease over the survey period. Capelin at age 3 dominated in the samples and were estimated to constitute more than 6 times the biomass of the other age groups combined. The 3-year-olds had an average length of 15.5 cm and weight 16.3 g. Maturation had progressed further in the western than the eastern area similar as last year, and quite a high proportion of the females sampled towards the end of the survey in the western area were spent. We undertook 7 stations with a submersible probe measuring acoustic target strength of capelin. Preliminary results indicate that the target strength and acoustic frequency response of capelin this year were more in accordance with expectations for capelin than last year. A thorough evaluation of this survey series and its usefulness as input to the capelin advice will be prepared for the capelin benchmark in June this year.publishedVersio

Optimization of sub-grid scale model for abrasive flow machining curved tube based on large eddy simulation

Abrasive flow machining technology is a new type of precision machining technology. Due to its unique rheological properties, it can process any complex structure and size parts to meet the requirements that conventional machining cannot meet. Combined with the turbulent flow characteristics of the abrasive flow, the large eddy simulation numerical method is used to simulate the machining process of the abrasive flow. The influence of different sub-grid scale models on the simulation results is discussed. Taking curved tube as the research object, the static pressure, dynamic pressure and velocity of different sub-grid models are analyzed to find the best sub-grid scale model. Large eddy simulation method is used to simulate the complex flow channel parts, and the best sub-grid scale model suitable for complex flow channels is determined, which reveals the grinding and polishing rule of abrasive flow and provides academic support for future research. Therefore, it has frontier and important research value

Shape effect of glyco-nanoparticles on macrophage cellular uptake and immune response

The shells of various poly(dl-lactide)-b-poly(acrylic acid) (PDLLA-b-PAA) spherical micelles and poly(l-lactide)-b-poly(acrylic acid) (PLLA-b-PAA) cylindrical micelles were functionalized with mannose to yield glyco-nanoparticles (GNPs) with different shapes and dimensions. All of these GNPs were shown to have good biocompatibility (up to 1 mg/mL). Cellular uptake experiments using RAW 264.7 have shown that the spherical GNPs were internalized to a much greater extent than the cylindrical GNPs and such a phenomenon was attributed to their different endocytosis pathways. It was demonstrated that spherical GNPs were internalized based on clathrin- and caveolin-mediated endocytosis while cylindrical GNPs mainly depended on clathrin-mediated endocytosis. We also found that longer cylindrical GNPs (Ln × Wn = 215 × 47 nm) can induce an inflammatory response (specifically interleukin 6) more efficiently than shorter cylindrical GNPs (Ln × Wn = 99 × 50 nm) and spherical GNPs (Dn = 46 nm)

Atlantic cod (Gadus morhua) larvae are attracted by low-frequency noise simulating that of operating offshore wind farms

The number and size of offshore wind (OW) turbines is increasing rapidly. OW turbines produce continuous, low-frequency noise that could impact marine fish dispersing/migrating through the facilities. Any such impact would be relevant for larval stages, which have limited possibility to swim away from OW facilities. If directional movement of fish larvae at sea is impacted by low-frequency continuous sound is unknown. We observe the behavior of Atlantic cod larvae (N = 89) in response to low-frequency sound while they are drifting in a Norwegian fjord inside transparent drifting chambers. We transmit 100 Hz continuous sound in the fjord, in the intensity range of OW turbines’ operational noise, and measure the sound pressure and 3-D particle motion. Half of the larvae (N = 45) are exposed to low-frequency (100 Hz) continuous sound, while the other half (N = 44) are observed under the same conditions but without the sound. Exposure does not affect the routine and maximum swimming speeds or the turning behavior of the larvae. Control larvae orient to the northwest. In contrast, exposed larvae orient towards the source of low-frequency sound and particle motion. This provides a basis to assess how OW might impact dispersal in this species.publishedVersio

Testing of trawl-acoustic stock estimation of spawning capelin 2021

This report describes the third in a series of trawl-acoustic monitoring surveys of the spawning stock of capelin during the migration to the coast. The survey is a response to a proposal from the industry to evaluate the possibility of using winter monitoring of maturing capelin as an input to the capelin assessment and advice. The timing and geographic coverage of the survey are such that they would be relevant to use for advice given that the output is reliable. Pre-defined areas off the Troms and Finnmark coast were covered using two vessels, Vendla surveying the western part and Eros the eastern part.Testing of trawl-acoustic stock estimation of spawning capelin 2021publishedVersio

Glyco-platelets with controlled morphologies via crystallization-driven self-assembly and their shape-dependent interplay with macrophages

Two-dimensional (2D) materials are of great significance to the materials community as a result of their high surface area and controllable surface properties. However, controlled preparation of biodegradable 2D structures with biological activity is difficult. In this work we demonstrate that by careful selection of building block structures and assembly conditions it is possible to use crystallization-driven self-assembly (CDSA) to assemble well-defined 2D nanostructures from poly­(l-lactide) (PLLA)-based diblock glycopolymers. 1D glyco-cylinders and 2D diamond-shaped glyco-platelets are produced, where the underlying formation mechanism is revealed by dissipative particle dynamics simulations. Furthermore, we demonstrate that assembly of the polymers under mild degradation provides a straightforward route to hollow-cored platelets, a morphology that has previously proven laborious to access. The well-defined sizes and shapes of the glyco-platelets allow us to investigate macrophage activation efficiency and demonstrate clear size and shape effects, pointing toward potential applications in immunology