In this article, I will point to a number of unexpected features of the early European understanding of the geography and toponymy of the Fiji Islands. First, the earliest visitors who compiled maps ...of parts of Fiji (Tasman in 1643, Cook in 1774, Bligh in 1789 and 1792, Wilson in 1797), had no contact with Fiji islanders, so all the toponyms listed on maps were of European origin. Second, lists of Fiji toponyms were published (Anderson 1777, Fanning 1807) before any appeared on maps. Third, because Fiji was commonly approached from Tonga, most of the early toponyms, and many of those that appeared on maps, were exonyms in Tongan, some of which have persisted in official use to this day.
In the interests of improving engagement with Pacific Island communities to enable development of effective and sustainable adaptation strategies to climate change, we looked at how traditional oral ...narratives in rural/peripheral Fiji communities might be used to inform such strategies. Interviews were undertaken and observations made in 27 communities; because the custodians of traditional knowledge were targeted, most interviewees were 70-79 years old.
The view that oral traditions, particularly those referring to environmental history and the observations/precursors of environmental change, were endangered was widespread and regretted. Interviewees’ personal experiences of extreme events (natural disasters) were commonplace but no narratives of historical (unwitnessed by interviewees) events were found. In contrast, experiences of previous village relocations attributable (mainly) to environmental change were recorded in five communities while awareness of environmentally driven migration was more common. Questions about climate change elicited views dominated by religious/fatalist beliefs but included some more pragmatic ones; the confusion of climate change with climate variability, which is part of traditional knowledge, was widespread.
The erosion of traditional environmental knowledge in the survey communities over recent decades has been severe and is likely to continue apace, which will reduce community self-sufficiency and resilience. Ways of conserving such knowledge and incorporating it into adaptation planning for Pacific Island communities in rural/peripheral locations should be explored.
The development of a high-performance polymer PBDT-BT for bulk heterojunction solar cell devices is summarized. The polymer was first synthesized by Stille polycondensation, and solar cell devices in ...conventional geometry were optimized through the use of a lithium salt cathode interlayer reaching 6% power conversion efficiency. Improvements were made to the synthesis of the polymer using Suzuki polycondensation giving high-molecular-weight material in the M n = 100 kg/mol range. Further device optimization in inverted geometry gave power conversion efficiency of over 9%. The synthesis scalability as well as the batch-to-batch reproducibility of the polymer were extensively investigated.
Nanoscale morphology and spin can have a significant impact on charge generation and short time scale recombination in organic photovoltaic materials. We reveal multiple efficient charge separation ...pathways and the suppression of triplet loss channels in a high-performing nematic liquid crystalline electron donor, benzodithiophene terthiophene rhodanine (BTR). BTR:PC71BM bulk heterojunction photovoltaic devices have been shown to exhibit charge generation quantum yields of ∼90% and power conversion efficiencies >9.5%, even in thick devices. Solvent vapor annealing increases device efficiency, delivering performance almost twice as high as that of untreated blend films, despite reduced exciton quenching. Broadband femtosecond transient absorption spectroscopy reveals both efficient hole and electron transfer on different time scales in the bulk heterojunction blends. BTR triplet excitons are formed due to subnanosecond bimolecular recombination in untreated blend films, though their formation is significantly suppressed after solvent vapor annealing. This treatment results in more crystalline BTR domains with three-dimensional percolation pathways that have an important impact on these terminal triplet loss channels formed through fast recombination of free charges. We propose that spin and nanoscale morphology have significant and interconnected roles in the prevention of loss channels that with careful control can lead to superior device performance in promising new photovoltaic materials.
Various ceria and colloidal silica polishing slurries were used to polish fused silica glass workpieces on a polyurethane pad. Characterization of the slurries' particle size distribution (PSD) ...(using both ensemble light scattering and single particle counting techniques) and of the polished workpiece surface (using atomic force microscopy) was performed. The results show the final workpiece surface roughness is quantitatively correlated with the logarithmic slope of the distribution function for the largest particles at the exponential tail end of the PSD. Using the measured PSD, fraction of pad area making contact, and mechanical properties of the workpiece, slurry, and pad as input parameters, an Ensemble Hertzian Gap (EHG) polishing model was formulated to estimate each particle's penetration, load, and contact zone. The model is based on multiple Hertzian contact of slurry particles at the workpiece–pad interface in which the effective interface gap is determined through an elastic load balance. Separately, ceria particle static contact and single pass sliding experiments were performed showing ~1‐nm depth removal per pass (i.e., a plastic type removal). Also, nanoindentation measurements on fused silica were made to estimate the critical load at which plastic type removal starts to occur (Pcrit~5 × 10−5 N). Next the EHG model was extended to create simulated polished surfaces using the Monte Carlo method where each particle (with the calculated characteristics described above) slides and removes material from the silica surface in random directions. The polishing simulation utilized a constant depth removal mechanism (i.e., not scaling with particle size) of the elastic deformation zone cross section between the particle and silica surface, which was either 0.04 nm (for chemical removal) at low loads (<Pcrit) or 1.0 nm (for plastic removal) at intermediate loads (>Pcrit). The simulated surfaces quantitatively compare well with the measured rms roughness, power spectra, surface texture, absolute thickness material removal rate, and load dependence of removal rate.
The synthesis of key 4-alkyl-substituted 5-(trimethylsilyl)thiophene-2-boronic acid pinacol esters
allowed a simplified alkylthiophene catenation process to access bis-, ter-, quater-, and ...quinquethiophene π-bridges for the synthesis of acceptor-π-bridge-donor- π-bridge-acceptor (A-π-D-π-A) electron donor molecules. Based on the known benzodithiophene-terthiophene-rhodanine (
) material, the
series of materials,
(X = M, monothiophene),
(X = B, bithiophene), known
(X = T, terthiophene),
(X = Q, quaterthiophene), and
(X = P(penta), quinquethiophene) were synthesised to examine the influence of chromophore extension on the device performance and stability for OPV applications. The
(x = 4, butyl, and x = 8, octyl) series of materials were synthesised by varying the oligothiophene π-bridge alkyl substituent to examine structure-property relationships in OPV device performance. The devices assembled using electron donors with an extended chromophore (
and
) are shown to be more thermally stable than the
containing devices, with un-optimized efficiencies up to 9.0% PCE.
has been incorporated as a secondary donor in ternary blend devices with
resulting in high-performance OPV devices with up to 10.7% PCE.
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