The costs of removing the unsanctioned import of marine plastic litter to small island states.

Small island states receive unprecedented amounts of the world's plastic waste. In March 2019, we removed as much plastic litter as possible from Aldabra Atoll, a remote UNESCO World Heritage Site, and estimated the money and effort required to remove the remaining debris. We removed 25 tonnes at a cost of $224,537, which equates to around $10,000 per day of clean-up operations or $8,900 per tonne of litter. We estimate that 513 tonnes (95% CI 212-814) remains on Aldabra, the largest accumulation reported for any single island. We calculate that removing it will cost approximately $4.68 million and require 18,000 person-hours of labour. By weight, the composition is dominated by litter from the regional fishing industry (83%) and flip-flops from further afield (7%). Given the serious detrimental effects of plastic litter on marine ecosystems, we conclude that clean-up efforts are a vital management action for islands like Aldabra, despite the high financial cost and should be integrated alongside policies directed at 'turning off the tap'. We recommend that international funding be made available for such efforts, especially considering the transboundary nature of both the marine plastic litter problem and the ecosystem services provided by biodiversity-rich islands.

Rapid Sensing of Biological and Environmental Analytes Using Microwave-Accelerated Bioassays and a MATLAB Application.

We report a method for rapid detection and analysis of biological and environmental analytes by microwave-accelerated bioassays (MABs) and a novel MATLAB-based image processing of colorimetric signals. In this regard, colorimetric bioassays for histidine-rich protein 2 (HRP-2) and microcystin-leucine arginine (MC-LR) toxin were carried out using MABs and without microwave heating (i.e, gold standard bioassays). Our MATLAB-based detection method is based on the direct correlation of color intensity of a solution calculated from images captured with a smartphone with the concentration of the biomolecule of interest using a MATLAB code developed in-house. We demonstrated that our MATLAB-based detection method can yield bioassay sensitivity comparable to the colorimetric gold standard tool, i.e., UV-Visible spectroscopy. In addition, colorimetric bioassay time for the HRP-2 assay (used in malaria diagnosis) and colorimetric MC-LR bioassay (used in MCLR toxin diagnosis) was reduced from up to 2 hours at room temperature without microwave heating to 15 minutes using the MABs technique.

Effect of Microwave Heating on the Crystallization of Glutathione Tripeptide on Silver Nanoparticle Films.

Effect of microwave heating on the crystallization of glutathione (GSH) tripeptide using the metal-assisted and microwave-accelerated evaporative crystallization (MA-MAEC) technique is reported. GSH crystals were grown from supersaturated solutions of GSH (300-500 mg/mL) on the iCrystal plates with silver nanoparticle films (SNFs) and without SNFs in three different microwave systems operating at 2.45 GHz: conventional (multimode, fixed power at 900W), industrial (monomode, variable power up to 1200 W), and the iCrystal system (monomode, variable power up to 100 W). The efficacy of the MA-MAEC technique, in terms of improvement in the crystallization time, crystal size and quality of GSH, was compared between the three microwave systems and the crystallization at room temperature (no microwave heating, a control experiment). Optical microscopy was used to visualize and quantify the growth of GSH crystals during and after microwave heating. Powder X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy data showed that GSH crystals had identical crystal structure to those grown at room temperature and microwave heating did not alter the chemical structure of GSH molecules during microwave heating, respectively. Using the MA-MAEC technique, the iCrystal system yielded high quality GSH crystals in a rapid manner.

Ultra-Rapid Crystallization of L-alanine Using Monomode Microwaves, Indium Tin Oxide and Metal-Assisted and Microwave-Accelerated Evaporative Crystallization.

The use of indium tin oxide (ITO) and focused monomode microwave heating for the ultra-rapid crystallization of L-alanine (a model amino acid) is reported. Commercially available ITO dots (< 5 mm) attached to blank poly(methyl)methacrylate (PMMA, 5 cm in diameter with 21-well silicon isolators: referred to as the iCrystal plates) were found to withstand prolonged microwave heating during crystallization experiments. Crystallization of L-alanine was performed at room temperature (a control experiment), with the use of two microwave sources: a 2.45 GHz conventional microwave (900 W, power level 1, a control experiment) and 8 GHz (20 W) solid state, monomode microwave source with an applicator tip that focuses the microwave field to a 5-mm cavity. Initial appearance of L-alanine crystals and on iCrystal plates with ITO dots took 47 ± 2.9 min, 12 ± 7.6 min and 1.5 ± 0.5 min at room temperature, using a conventional microwave and focused monomode microwave heating, respectively. Complete evaporation of the solvent using the focused microwaves was achieved in 3.2 ± 0.5 min, which is ~52-fold and ~172-fold faster than that observed at room temperature and using conventional microwave heating, respectively. The size and number of L-alanine crystals was dependent on the type of the 21-well iCrystal plates and the microwave heating method: 33 crystals of 585 ± 137 µm in size at room temperature > 37 crystals of 542 ± 100 µm in size with conventional microwave heating > 331 crystals of 311 ± 190 µm in size with focused monomode microwave. FTIR, optical microscopy and powder X-ray diffraction analysis showed that the chemical composition and crystallinity of the L-alanine crystals did not change when exposed to microwave heating and ITO surfaces. In addition, theoretical simulations for the binding of L-alanine molecules to ITO and other metals showed the predicted nature of hydrogen bonds formed between L-alanine and these surfaces.