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Synres (U.K.) Ltd., Six Acre House, 17 Town Square, Sale M33 1XZ, Cheshire, report the following recent additions to their range of additives.

This study aims to achieve the fabrication of three-dimensional core-shell filament-based lattice structures by means of robocasting combined with co-extrusion. For core and shell materials, colloidal gels composed of submicron carbon and alumina powders were developed, respectively. Simultaneously, the co-extrusion process was also studied by numerical simulation to investigate the feed pressure-dependent wall thickness.

Significant differences in the rheological behavior of the carbon and alumina gels were observed because of differences of the particle morphology and surface chemistry of the carbon and alumina powders. Precise control over the cross-sectional diameter of the core and shell green state elements was achieved by alteration of the feed pressures used during co-extrusion.

After subsequent thermal treatment in an oxidizing atmosphere (e.g. air), in which the carbon core was oxidized and burned out, lattice structures formed of hollow filaments of predetermined wall thickness were manufactured; additionally, C-Al₂O₃ core-shell filament lattice structures could be derived after firing in an argon atmosphere.

Green lattice truss structures with carbon core and alumina shell filaments were successfully manufactured by robotically controlled co-extrusion. As feedstocks carbon and alumina gels with significantly different rheological properties were prepared. During co-extrusion, the core paste exhibited a much higher viscosity than the shell paste, which benefited the co-extrusion process. Simultaneously, the core and shell diameters were exactly controlled by core and shell feed pressures and studied by numerical simulation. The experimentally and numerically derived filament wall thickness showed qualitative agreement with each other; with decreasing core pressure during co-extrusion, the wall thickness increased.

Most foods are complex mixtures of some or all of the following classes of chemical substances: carbohydrates, fats, proteins, minerals or inorganic compounds, vitamins, colours, flavouring substances, water, and miscellaneous substances. Since foods are mixtures of chemical compounds, the effects of cooking, processing and storage involve chemical changes in these components, and it is therefore desirable to look at these in turn.

The review of food consumption elsewhere in this issue shows the broad pattern of food supplies in this country; what and how much we eat. Dietary habits are different to what they were before the last War, but there have been few real changes since the end of that War. Because of supplies and prices, shifts within commodity groups have occurred, e.g. carcase meat, bread, milk, but overall, the range of foods commonly eaten has remained stable. The rise of “convenience foods” in the twenty‐five year since the War is seen as a change in household needs and the increasing employment of women in industry and commerce, rather than a change in foods eaten or in consumer preference. Supplies available for consumption have remained fairly steady throughout the period, but if the main food sources, energy and nutrient content of the diet have not changed, changes in detail have begun to appear and the broad pattern of food is not quite so markedly stable as of yore.

Rapid prototyping of ceramics is accomplished with stereolithography by using an SLA machine to build the ceramic green from a UV‐curable suspension of ceramic powders ‐ a “ceramic resin”. Objects are later sintered in a separate furnace to complete the process. Aluminium oxide resins based on hexanediol diacrylate are characterized for curing behaviour by photo‐rheology and differential photo calorimetry with a UV lamp, and with an HeCd laser using “windowpanes”, single strings, and walls.

The aim of this paper is to provide an easy method of extrusion freeforming to fabricate microwave electromagnetic bandgap (EBG) crystals. EBG crystals are periodic dielectric structures that can block wave propagation and generate a bandgap. These crystals can be used in high capability antennae, electromagnetic wave semiconductors, microresonators, high‐reflectivity mirrors and polarizing beam splitters.

The effects of extrusion process parameters and paste characteristics were investigated. Finally, one‐period and two‐period woodpile EBG crystals with bandgaps in the frequency region of 90‐110 GHz were fabricated and the bandgap was measured.

The filament diameter is influenced by whether extrusion is carried out with or without a substrate and by the free fall‐distance from the nozzle. The quality of lattice structures is dependent on paste flow and properties. A ceramic paste with 60 vol. % (the fraction of ceramic powder based on solvent‐free polymer) was well suited to fabrication. The solvent content also influenced the fabrication. The experimental results show that under ∼12 per cent solvent mass fraction in the paste and relatively high extrusion ram velocity (more than 0.014 mm/s) at a pressure of 14 MPa, samples with high quality were fabricated.

This paper demonstrates that the rapid prototyping method of extrusion freeforming can be applied for the fabrication of EBG crystals from ceramic powders and the important factors which influence the product quality are identified.

THE author believes that at the time of presenting this paper there does not exist in Great Britain a company who will produce steel or high melting point non‐ferrous alloy castings by the Lost Wax Process on a commercial basis to the trade.

The purpose of this paper is to study the compound effect between silane and cerium salts in the passivation process of chemical conversion treatment of zinc.

Chemical conversion treatment using 3‐Glycidoxypropyltrimethoxysilane on zinc is investigated as an alternative treatment to chromate conversion. The surface chemistry of the silane‐treated samples is investigated with mass change measurements, polarization curves, electrochemical impedance spectroscopy (EIS) and the salt spray tests (SST). The surface morphology of samples was studied using a scanning electron microscope.

The polarization curves, EIS and SST data are in agreement. On the surface of zinc, the silane formed a compound with the cerium, thus enhancing the adhesion and corrosion resistance of the polymer film.

There have been few reports on the compound effects of silanes and cerium salts in the passivation process. The mechanism of this compound effect may be due to the ability of Ce^3 +ions to gain access to the interface through tiny cracks or micropores in the cross‐linking structure of GPS polymer films on zinc, and the subsequent oxidation of Ce^3 +to Ce^4 +by H₂O₂ may result in a barrier effect between the electrolyte and the metallic substrate.

The purpose of this paper is to acquaint the readers with recent developments in biopolymer-based food packaging materials like natural biopolymers (such as starches and proteins), synthetic biopolymers (such as poly lactic acid), biopolymer blending and nanocomposites grounded on natural and synthetic biopolymers. This paper is an attempt to draw the readers towards the advantages and attributes of new era polymers to diminish the usage of traditional non-biodegradable polymers.

Plastic packaging for food and associated applications is non-biodegradable and uses up valuable and treasured non-renewable petroleum products. With the current focus on researching alternatives to petroleum, research is progressively being channelized towards the development of biodegradable food packaging, thereby reducing adverse impact on the environment.

Natural biopolymer-based nanocomposite packaging materials seem to have a scintillating future for a broad range of applications in the food industry, including advanced active food packaging with biofunctional attributes. The present review summarizes the scientific information of various packaging materials along with their attributes, applications and the methods for production.

This is an apropos review as there has been a recent renewed concern in research studies, both in the industry and academe, for development of new generation biopolymer-based food packaging materials, with possible applications in many areas.