The future of aquatic protein: implications for protein sources in aquaculture diets

Approximately 70% of the aquatic-based production of animals is fed aquaculture, whereby animals are provided with high-protein aquafeeds. Currently, aquafeeds are reliant on fish meal and fish oil sourced from wild-captured forage fish. However, increasing use of forage fish is unsustainable and, because an additional 37.4 million tons of aquafeeds will be required by 2025, alternative protein sources are needed. Beyond plantbased ingredients, fishery and aquaculture byproducts and insect meals have the greatest potential to supply the protein required by aquafeeds over the next 10–20 years. Food waste also has potential through the biotransformation and/or bioconversion of raw waste materials, whereas microbial and macroalgal biomass have limitations regarding their scalability and protein content, respectively. In this review, we describe the considerable scope for improved efficiency in fed aquaculture and discuss the development and optimization of alternative protein sources for aquafeeds to ensure a socially and environmentally sustainable future for the aquaculture industry

Development and spatio-spectral mapping of a capillary high harmonic source

This work describes the development and operation of a capillary based High Harmonic Generation (HHG) system. Using this system a coherent beam of soft x-rays is generated, studied and applied. A series of experiments was then undertaken in order to deepen our knowledge of the HHG process and to optimise the performance of the source. Notable contributions made to the field are: A novel laser mode quality measuring device. (Laser mode quality strongly affects the efficiency of the capillary launch). A study of the spectral output of the system as a function of gas pressure, laser power, and laser spectral phase. An analysis technique for recovering spatially-resolved spectral information about a beam by studying the Fresnel diffraction pattern produced at an array of apertures. A study of pulse compression using cascaded quadratic nonlinearity for spectral broadening

On the effect of functionalizer chain length and water content in polyethylene/silica nanocomposites: Part I — Dielectric properties and breakdown strength

A series of nanoparticles was prepared by functionalizing a commercial nanosilica with alkylsilanes of varying alkyl tail length, from propyl to octadecyl. By using a constant molar concentration of silane, the density of alkyl groups attached to each system should be comparable. The effect of chain length on the structure of the resulting nanosilica/polyethylene nanocomposites was examined and comparison with an unfilled reference system revealed that, other than through a weak nucleating effect, the inclusion of the nanosilica does not affect the matrix structure. Since water interacts strongly with applied electric fields, water was used as a dielectric probe in conjunction with dielectric spectroscopy to examine the effect of the nanofiller and its surface chemistry on the system. Sets of samples were prepared through equilibrating under ambient conditions, vacuum drying and water immersion. While the water content of the unfilled polymer was not greatly affected, the water content of the nanocomposites varied over a wide range as a result of water accumulation, in a range of states, at nanoparticle interfaces. The effect of water content on breakdown behavior was also explored and, in the unfilled polymer, the breakdown strength was found to depend little on exposure to water (~13% reduction). In all the nanocomposites, the increased propensity for these systems to absorb water meant that the breakdown strength was dramatically affected (>66% reduction)

On the effect of functionalizer chain length and water content in polyethylene/silica nanocomposites: Part II – Charge Transport

The effects of functionalizer chain length and water content were explored in a series of polyethylene/silica nanocomposites. Silane molecules with differing chain lengths (propyl, octyl and octadecyl) were used to vary the nanoparticle surface chemistry, while vacuum drying and water immersion were used to extract water from or add water to samples previously equilibrated under ambient conditions. Electrical conductivity was found to be highly dependent upon water content, while space charge distributions measured using the pulsed electro-acoustic technique revealed that both the rate of charge injection at the electrode interfaces and the charge mobility within the sample bulk were strongly dependent on absorbed water. Changes to the charge transport dynamics due to the functionalizer chain length were, however, subtle. The removal of surface hydroxyl groups appears to be the primary mechanism by which functionalization influences electrical behavior; this reduces water uptake and, as a consequence, modifies charge transport behavior

Microscale deposition of 2D materials via Laser Induced Backwards Transfer

2D materials such as graphene have great potential as the basis for novel optoelectronic devices. Typically, 2D materials are produced via chemical vapor deposition and therefore form continuous layers. Here Laser Induced Backwards Transfer (LIBT) is used to deposit pixels of 2D materials with precisely controlled size, shape and position. In LIBT, part of the laser energy that is absorbed in the donor substrate becomes kinetic energy imparted to the 2D material, causing localised transfer of 2D material onto the receiver. The capability to deposit high-quality intact 2D materials, in well-defined microscale pixels will eliminate costly and time-consuming lithographic processing.ABSTRACT (250 words for technical review)Laser Induced Backwards Transfer (LIBT)1 is a candidate for next generation additive manufacturing, especially for materials that are unsuited to more conventional methods. Broadening the range and complexity of materials that can be deposited will enable developments in material functionality e.g. for sensing applications, metamaterials and silicon photonics. Here we demonstrate LIBT as a means of achieving intact transfer of 2D materials (such as graphene and MoS2) onto a receiver substrate (which could be a silicon based electronic or photonic device). Typically, 2D materials are produced via chemical vapor deposition and form featureless, continuous layers. In LIBT, part of the laser pulse energy that is absorbed in the donor substrate becomes kinetic energy imparted to the 2D material, this causes localised detachment and transfer of the 2D material onto the receiver. Here, the transfer region is defined by beam-shaping using a Digital Micromirror Device (DMD)2 allowing precise control over the size, shape and positioning of the 2D material deposition. We use high resolution imaging to observe removal of 2D material from the donor substrate and present Raman analysis of the receiver substrate, verifying both that transfer has occurred and that the 2D materials retain their high quality and viability for end applications.[1] Feinäugle, M. et al., "Laser-induced backward transfer of nanoimprinted polymer elements," Applied Physics A 122(4), 1-5 (2016). [2] Heath, D. J. et al., "Dynamic spatial pulse shaping via a digital micromirror device for patterned laser-induced forward transfer of solid polymer films," Optical Materials Express 5(5), 1129-1136 (2015). <br/

Laser Induced Backwards Transfer (LIBT) of graphene onto glass

Graphene growth is typically optimized for uniformity over relatively large areas; however, this can place undesirable limitations on the design of graphene-based devices and can mandate the use of additional lithographic processing steps. Localized transfer of graphene can therefore offer significant benefits, permitting greater freedom in device design thereby enabling new applications. We present results obtained using a laser transfer method which is capable of localized deposition of graphene onto transparent receiver materials such as glass (using just a single fs laser pulse per deposited structure). In this method (laser induced backwards transfer, LIBT [1-3]) a pulsed laser beam is focussed through the receiving substrate and onto the donor substrate (hence the requirement for the receiver to be transparent). In this case the receiver is a microscope cover glass which is held in close contact with the donor during LIBT. The donor is a nickel coated glass slide upon which large-area monolayer graphene is transferred via the floating film technique with the aid of a PMMA support layer that is subsequently dissolved. The focused laser pulse is absorbed within the metal layer of the donor causing rapid, localized, thermal expansion (a shockwave). This ejects the graphene from the donor surface (only where the laser was focused) and transfers it to the receiver substrate. In this manner, microscale patterning of graphene on the receiver substrate is achieved.Additionally, we present details of spatial beam modulation via a digital micromirror device (DMD, [4, 5]) which allows the shape and size of the deposited graphene to be precisely, computer controlled in the micron range. This innovation could help to facilitate rapid prototyping of graphene-based devices, allowing numerous design variations to be tested quickly and without requiring the purchase of multiple, costly, lithographic masks. This work extends on previous results obtained by the authors at a laser wavelength of 800nm [6] by using an optical parametric amplifier (OPA) to generate laser light at 1650nm and additionally introduces control over laser pulse duration, allowing switching between 200fs and 1200fs pulses.The presence of graphene on a surface creates a slight change in optical reflectance and so it is often possible (although difficult) to observe the presence of localized deposits of graphene via optical microscopy. We have developed image processing methods (with contrast enhancement and image segmentation steps) that greatly simplify the identification of graphene coated regions. These methods have been evaluated using Raman microscopy and have proved to be an accurate and convenient tool (see Figure 1) which we believe may be of interest to other researchers in this field

Vacuum current emission and initiation in an LaB6 hollow cathode

This paper presents the first investigation of pre-ignition currents and the ignition process in an LaB6 hollow cathode running on krypton propellant. Vacuum and pre-ignition currents are found to be consistent with space charge limited behaviour. A novel, low power ignition strategy with the potential to reduce insert and orifice erosion is also shown

Dataset for: The effects of Hydration on the DC Breakdown Strength of Polyethylene Composites Employing Oxide and Nitride Fillers

This dataset is intended to be used in conjunction with the journal publication; &quot;The effects of Hydration on the DC Breakdown Strength of Polyethylene Composites Employing Oxide and Nitride Fillers&quot; Authors: I. L. Hosier, M. Praeger, A. S. Vaughan and S. G. Swingler to be published in IEEE Transactions on Dielectrics and Electrical Insulation (accepted for publication 27th April 2017) The excel file contains the raw data used to generate each figure on a seperate tab. Abstract: Particle dispersion, water absorption/desorption and electrical breakdown behavior were studied in a range of polyethylene composites having a common matrix morphology. Three different conditioning routes (dry, ambient and wet) were used to vary the absorbed water content. Systems employing oxide fillers (silica and alumina) were found to have poor or intermediate levels of particle dispersion and could absorb/desorb significant amounts of water. Consequently, they required drying to provide breakdown strengths comparable to that of the host matrix. Systems based on calcined silica exhibited reduced water absorption and provided improved breakdown strength after ambient conditioning, despite having an identical dispersion to those utilizing untreated silica. Composites employing nitride fillers (silicon nitride and aluminum nitride) were found to have good or intermediate levels of particle dispersion. These absorbed far less water and hence provided breakdown strength values comparable to that of the host matrix following ambient conditioning. Their breakdown strength was degraded after wet conditioning with both exhibiting similar breakdown strengths despite there being a large difference in the level of particle dispersion between the two fillers. In composites based upon a hydrophobic host matrix, water absorption is largely determined by particle surface chemistry and, although the above results are presented in terms of water absorption, we suggest that changes in this characteristic can be interpreted as a proxy for changed surface chemistry. The results suggest that surface chemistry is at least as important as particle dispersion in determining the electrical breakdown strength.</span

Dataset for: The effects of water on the dielectric properties of aluminum based nanocomposites

This dataset should be used in conjunction with the journal publication; &quot;The effects of water on the dielectric properties of aluminum based nanocomposites&quot; Authors: Ian L Hosier, Matthew Praeger, Alun S. Vaughan and Steve G Swingler in: IEEE Transactions on Nanotechnology, Vol. 16, no. 4, pp. 1-10, July 2017 The excel file contains the raw data used to generate each figure on a separate tab. Note: The figure ExtraTGAwork.TIF is a graphic of the effects of wet and dry conditioning on water uptake. It is mentioned in the text of the paper but there was insufficient room to include it in the manuscript. Abstract: A series of polyethylene nanocomposites was prepared utilizing aluminum nitride or alumina nano-powders with comparable morphologies. These were subsequently subjected to different conditioning regimes, namely prolonged storage in vacuum, the ambient laboratory environment or in water. The effect of filler loading and conditioning (i.e. water content) on their morphological and dielectric properties was then examined. Measurements indicated that, in the case of aluminum nitride nanocomposites, none of the conditioning regimes led to significant absorption of water and, as such, neither the dielectric properties nor the DC conductivity varied. Conversely, the alumina nanocomposites were prone to the absorption of an appreciable mass of water, which resulted in them displaying a broad dielectric relaxation, which shifted to higher frequencies, and a higher DC electrical conductivity. We ascribe these different effects to the interfacial surface chemistry present in each system and, in particular, the propensity for hydrogen bonding with water molecules diffusing through the host matrix. Technologically, the use of nanocomposites based upon systems such as aluminum nitride, in place of the commonly used metal oxides (alumina, silica, etc.), eliminates variations in dielectric properties due to absorption of environmental water without resorting to the adoption of techniques such as surface functionalization or calcination in an attempt to render nanoparticle surface chemistry hydrophobic.</span