Observations on the pollination of Pelargonium tricolor, section Campylia (Geraniaceae)

A group of four species of Pelargonium L’Hérit. in the section Campylia (Sweet) DC. have embossed ‘warty areas’ at the bases of the posterior petals of the zygomorphic flowers. In Pelargonium tricolor Curt, these embossed areas are most distinctive. The significance of these embossed areas in the attraction of insect pollinators is discussed. From repeated observations of P. tricolor it is concluded that these areas are false nectaries and that they are effective in attracting dipteran pollinators. Megapalpus capensis Wiedemann (Diptera: Bombyliidae), in particular, exhibits strong association with these false nectaries. It is further predicted that the embossed areas on the petals of the remaining three species in the group, namely P. capillare (Cav.) Willd., P. ocellatum J.J.A. van der Walt and P. incarnatum (L’Hérit.) Moench have similar value for attracting anthophilous insects

A CASE STUDY OF RAPID SAND CASTING DEFECTS

ArticleRapid sand casting is quickly transforming as an established method for the production of sand moulds and cores for metal casting applications by additive manufacturing processes. The case study investigated possible sand casting defects resulting from a local implementation of rapid sand casting referred to as Rapid Casting for Tooling (RCT). Poor workmanship of the RCT process chain was found to be the root cause of sand casting defects including cold lap, gas porosity and alignment faults

Evaluating the Suitability of Alumide Tooling for Injection Moulding of Different Polymers

Published ArticleThis paper describes the possibility of using laser-sintered Alumide® as an alternative material for producing rapid tooling (RT) inserts. To determine the durability of Alumide® inserts for the injection moulding (IM) process, a product with geometrical features was developed, and Alumide® inserts were manufactured. Polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), and polyamide 6 (PA 6) were used for IM trials with the Alumide® inserts. From these trials, it was concluded that polymer materials with a processing temperature of about 230 ºC, similar to PP and ABS, can be used with Alumide® inserts as RT inserts for the IM process

Additive manufacturing of alumide jewellery

Additive Manufacturing (AM) has been used for various jewellery applications in the recent past - both through direct and indirect use of AM products. The typical trend for direct manufactured jewellery has however, been dominated by metals-based applications. Materialise, through their MGX collection, has helped to set a new trend of doing functional design / functional art through amongst others, direct laser sintered polymers. They have created a significant demand for direct manufactured products that are not possible to manufacture with conventional technologies. More importantly, some of these designs enable an element of personalisation, to lead to "bespoke art". Within a collaborative research project between De Montfort University (UK), Loughborough University (UK) and Vaal University of Technology (SA), one of the specific research outcomes was aimed at producing designs for direct AM jewellery in AlumideTM, an Aluminum and Nylon matrix. The objective was to go beyond complex shapes, to also create innovative techniques for insertion of gemstones in these designs, to result in limited production of "bespoke jewellery series". The paper and associated presentation will report on work in progress from the collaborative project, and will discuss first results, problem areas and future possibilities

Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016

The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, E >100 GeV) -rays. VHE -ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE -ray intranight variability in this source. While a common variability timescale of 1.5 hr is found, there is a significant deviation near the end of the flare with a timescale of ∼ 20 min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, curvature is detected in the VHE -ray spectrum of PKS 1510-089, which is fully explained through absorption by the extragalactic background light. Optical R-band observations with ATOM reveal a counterpart of the -ray flare, even though the detailed flux evolution differs from the VHE lightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, E >100 MeV) -ray band only a moderate flux increase is observed with Fermi-LAT, while the HE -ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the -ray spectrum indicates that the emission region is located outside of the BLR. Radio VLBI observations reveal a fast moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located ∼ 50 pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this correlation is indeed true, VHE rays have been produced far down the jet where turbulent plasma crosses a standing shock.Accepted manuscrip