The effect of laser power, traverse velocity and spot size on the peel resistance of a polypropylene/adhesive bond

Abstract The mean peel resistance force achieved with respect to variation in the laser power, incident spot traverse velocity and incident spot diameter between linear low density polyethylene film backed by a thin commercial adhesive coating that were bonded to a polypropylene substrate via thermal activation provided by a 27W CO 2 laser is discussed in this work. The results gathered for this work have been used to generate a novel empirical tool that predicts the CO 2 laser power required to achieve a viable adhesive bond for this material combination. This predictive tool will enable the packaging industry to achieve markedly increased financial yield, process efficiency, reduced material waste and process flexibility. A laser spot size dependent linear increase in laser line energy was necessary for this material combination, suggesting the minimal impact of thermal strain rate. Moreover a high level of repeatability around this threshold laser line energy was indicated, suggesting that laser activated adhesive bonding of such polymer films is viable. The adhesion between the material combination trialled here responded linearly to thermal load. In particular, when using the smallest diameter laser spot, it is proposed that the resulting high irradiance caused film or adhesive material damage; thus, resulting in reduced peel resistance force. The experimental work conducted indicated that the processing window of an incident CO 2 laser spot increases with respect to spot diameter, simultaneously yielding greater bond stability in the face of short-term laser variance

Biodiversity in urban gardens: assessing the accuracy of citizen science data on garden hedgehogs

Urban gardens provide a rich habitat for species that are declining in rural areas. However, collecting data in gardens can be logistically-challenging, time-consuming and intrusive to residents. This study examines the potential of citizen scientists to record hedgehog sightings and collect habitat data within their own gardens using an online questionnaire. Focussing on a charismatic species meant that the number of responses was high (516 responses were obtained in 6 weeks, with a ~ 50:50% split between gardens with and without hedgehog sightings). While many factors commonly thought to influence hedgehog presence (e.g. compost heaps) were present in many hedgehog-frequented gardens, they were not discriminatory as they were also found in gardens where hedgehogs were not seen. Respondents were most likely to have seen hedgehogs in their garden if they had also seen hedgehogs elsewhere in their neighbourhood. However, primary fieldwork using hedgehog ‘footprint tunnels’ showed that hedgehogs were found to be just as prevalent in gardens in which hedgehogs had previously been reported as gardens where they had not been reported. Combining these results indicates that hedgehogs may be more common in urban and semi-urban gardens than previously believed, and that casual volunteer records of hedgehogs may be influenced more by the observer than by habitat preferences of the animal. When verified, volunteer records can provide useful information, but care is needed in interpreting these data

Plastid genome characterisation in Brassica and Brassicaceae using a new set of nine SSRs.

We report a new set of nine primer pairs specifically developed for amplification of Brassica plastid SSR markers. The wide utility of these markers is demonstrated for haplotype identification and detection of polymorphism in B. napus, B. nigra, B. oleracea, B. rapa and in related genera Arabidopsis, Camelina, Raphanus and Sinapis. Eleven gene regions (ndhB-rps7 spacer, rbcL-accD spacer, rpl16 intron, rps16 intron, atpB-rbcL spacer, trnE-trnT spacer, trnL intron, trnL-trnF spacer, trnM-atpE spacer, trnR-rpoC2 spacer, ycf3-psaA spacer) were sequenced from a range of Brassica and related genera for SSR detection and primer design. Other sequences were obtained from GenBank/EMBL. Eight out of nine selected SSR loci showed polymorphism when amplified using the new primers and a combined analysis detected variation within and between Brassica species, with the number of alleles detected per locus ranging from 5 (loci MF-6, MF-1) to 11 (locus MF-7). The combined SSR data were used in a neighbour-joining analysis (SMM, D (DM) distances) to group the samples based on the presence and absence of alleles. The analysis was generally able to separate plastid types into taxon-specific groups. Multi-allelic haplotypes were plotted onto the neighbour joining tree. A total number of 28 haplotypes were detected and these differentiated 22 of the 41 accessions screened from all other accessions. None of these haplotypes was shared by more than one species and some were not characteristic of their predicted type. We interpret our results with respect to taxon differentiation, hybridisation and introgression patterns relating to the 'Triangle of U'