CASTING SOLVENT CONTROLLED-RELEASE OF CHLORHEXIDINE FROM ETHYLCELLULOSE FILMS PREPARED BY SOLVENT EVAPORATION

Chlorhexidine release from ethylcellulose films east from solvents of different dichloromethane/ethanol compositions was studied. Release rate was proportional to the square root of time. Increased ethanol content within the casting solvent significantly enhanced release rate. Release rate and cumulative mass released at different time periods (5, 10, 15 and 25 days) were proportional to the solubility parameter of the casting solvent.

Physiological effects of platyhelminth RFamide peptides on muscle-strip preparations of Fasciola hepatica (Trematoda: Digenea)

The effects of each of the known platyhelminth neuropeptides were determined on muscle-strip preparations from the liver fluke, Fasciola hepatica. The activity of synthetic replicates of the C-terminal nonapeptide of neuropeptide F (NPF9, Moniezia expansa), and the FMRFamide-related peptides (FaRPs), GNFFRFamide, RYIRFamide, GYIRFamide and YIRFamide, were examined. Muscle-strip activity was recorded from 1 mm segments of muscle prepared from 28 to 32-day-old worms, using a photo-optic transducer system. None of the peptides (less than or equal to 10 mu M) altered baseline tension significantly; however, each of the peptides increased the amplitude and frequency of muscle contraction. The threshold for activity of each of the peptides examined was, respectively, 1 nM (RYIRFamide), 0.3 mu M (GYIRFamide and YIRFamide), and 10 mu M (GNFFRFamide and NPF9). All of the effects were reversible and repeatable, following wash-out. Muscle-strip integrity was tested following experimentation, using arecoline (10 mu M) and high-K+ bathing medium (90 mM K+).

Predicting die life from die temperature for high pressure dies casting

The objective of this research was to determine the surface temperature of a high pressure die casting die during casting conditions. This was achieved by instrumentation of an insert which was placed in the shotplate region of the die. This research overcame the challenge of directly measuring the die surface temperature during a HPDC production casting cycle and shows that this is an effective method to determine the die surface temperature during the casting cycle. The instrumentation results gave a peak and minimum temperature of 500 C and 240 C respectively during steady state running conditions with a molten aluminium casting temperature of 660 C. Stress analysis from the steady state measured temperature of the die surface was calculated through a simple FEA model and the resulting stress uctuation was applied to a fatigue equation for the die material, the predicted number of cycles for cracking to start was found to correlate well with observed die damage.

Stress correlation between instrumentation and simulation analysis of the die for high pressure die casting

A strain gauge instrumentation trial on a high pressure die casting ‘HPDC’ die was compared to a corresponding simulation model using Magmasoft® casting simulation software at two strain gauge rosette locations. The strains were measured during the casting cycle, from which the von Mises stress was determined and then compared to the simulation model. The von Mises stress from the simulation model correlated well with the findings from the instrumentation trial, showing a difference of 5.5%, ~ 10 MPa for one strain gauge rosette located in an area of low stress gradient. The second rosette was in a region of steep stress gradient, which resulted in a difference of up to 40%, ~40 MPa between the simulation and instrumentation results. Factors such as additional loading from die closure force or metal injection pressure which are not modelled by Magmasoft® were seen to have very little influence on the stress in the die, less than 7%.

Late Bronze Age casting debris and other base metal finds from Haughey’s Fort

This paper provides a full overview of base metal finds from the excavations conducted at Haughey's Fort between 1987 and 1995. Most of the assemblage consists of waste metal from casting activities relating to the Late Bronze Age occupation of the site. A small minority of objects are of a later date, mostly Iron Age. Both the latter and the vast majority of Late Bronze metal items were recovered from a specific sector of the inner enclosure. Typological parallels, context and chronology of the finds are discussed, and a tentative interpretation of the evidence proposed.

Non-reciprocity in doubly periodic strip arrays on ferrite-dielectric substrate

Doubly periodic arrays of strip conductors printed on a composite ferrite-dielectric substrate have been investigated at oblique incidence of linear polarized plane waves. The simulation results revealed strong non-reciprocity of wave reflectance and transmittance at positive and negative angles of incidence. It is also shown that the non-reciprocity is further enhanced by the strip conductor pattern. 

Characterisation of phase composition, microstructure and microhardness of electroless nickel composite coating co-deposited with SiC on casting aluminium LM24 alloy substrate

Electroless Ni-P (EN) and composite Ni-P-SiC (ENC) coatings were developed on cast aluminium alloy, LM24. The coating phase composition, microstructure and microhardness were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness tester, respectively, on as-plated and heat-treated specimens. The original microstructure of the Ni-P matrix is not affected by the inclusion of the hard particles SiC. No formation of Ni-Si phase was observed upto 500°C of heat treatment. The microhardness is increased on incorporation of SiC in Ni-P matrix. The hardening mechanism is the formation of intermetallic phase Ni3P on annealing at elevated temperature. Overall, the composite coating (ENC) was found to be superior as compared to particles free (EN) coating in both as-deposited and heat-treated conditions.