RESUMO
This study aimed to analyze the effect of pre-heat treatment on bamboo strand properties and its impact on the properties of the resulting bamboo-oriented strand board (BOSB). Giant bamboo (Dendrocalamus asper (Schult.) Backer) with a density of 0.53 g cm-3 was converted into bamboo strands. These strands were pre-heat-treated at 140 and 160 °C for a duration of 1, 2, and 3 h. Changes in the chemical composition of the strand due to subsequent treatment were assessed. Fourier-transform infrared spectroscopy (FTIR) and X-Ray diffraction analysis (XRD) were used to determine the changes in the chemical composition of bamboo strands. The BOSB panels were produced with a target density of 0.7 g cm-3. The manufacturing of the BOSB was conducted in three layers with a ratio of 25:50:25, bonded with phenol-formaldehyde resin. The physical and mechanical properties of the laboratory-fabricated BOSB were tested in compliance with the criteria given in JIS A 5908 standards. Comparisons were made against OSB CSA 0437.0 Grade O-1 commercial standard. The pre-heat treatment led to chemical alterations within the material when set at 140 and 160 °C for 1 to 3 hours (h). FTIR spectral analysis demonstrated that longer exposure and higher temperatures resulted in fewer functional groups within the bamboo strands. The increased temperature and duration of pre-heat treatment enhanced the crystallinity index (CI). The dimensional stability and mechanical properties of the composites were improved significantly as hemicellulose and extractive content were reduced. This study demonstrated that the pre-heat treatment of bamboo strands at a temperature of 160 °C for a duration of 1 h was an adequate approach for heat modification and fabrication of BOSB panels with acceptable properties according to OSB CSA 0437.0 Grade O-1 commercial standard.
RESUMO
BACKGROUND: Indonesia has high mosquito diversity, with circulating malaria and arboviruses. Human landing catches (HLC) are ethically questionable where arboviral transmission occurs. The host decoy trap (HDT) is an exposure-free alternative outdoor sampling device. To determine HDT efficacy for local culicids, and to characterize local mosquito fauna, the trapping efficacy of the HDT was compared to that of HLCs in one peri-urban (Lakkang) and one rural (Pucak) village in Sulawesi, Indonesia. RESULTS: In Lakkang the outdoor HLCs collected significantly more Anopheles per night (n = 22 ± 9) than the HDT (n = 3 ± 1), while the HDT collected a significantly greater nightly average of Culex mosquitoes (n = 110 ± 42), than the outdoor HLC (n = 15.1 ± 6.0). In Pucak, there was no significant difference in Anopheles collected between trap types; however, the HDT collected significantly more Culex mosquitoes than the outdoor HLC nightly average (n = 53 ± 11 vs 14 ± 3). Significantly higher proportions of blood-fed mosquitoes were found in outdoor HLC (n = 15 ± 2%) compared to HDT (n = 2 ± 0%). More blood-fed culicines were collected with outdoor HLC compared to the HDT, while Anopheles blood-fed proportions did not differ. For the HDT, 52.6%, 36.8% and 10.5% of identified blood meals were on cow, human, and dog, respectively. Identified blood meals for outdoor HLCs were 91.9% human, 6.3% cow, and 0.9% each dog and cat. Mosquitoes from Pucak were tested for arboviruses, with one Culex pool and one Armigeres pool positive for flavivirus, and one Anopheles pool positive for alphavirus. CONCLUSIONS: The HDT collected the highest abundance of culicine specimens. Outdoor HLCs collected the highest abundance of Anopheles specimens. Although the HDT can attract a range of different Asian mosquito genera and species, it remains to be optimized for Anopheles in Asia. The high proportion of human blood meals in mosquitoes collected by outdoor HLCs raises concerns on the potential exposure risk to collectors using this methodology and highlights the importance of continuing to optimize a host-mimic trap such as the HDT.