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Rare earths, scandium, yttrium, and the fifteen lanthanoids from lanthanum to lutetium, are classified as critical metals because of their ubiquity in daily life. They are present in magnets in cars, especially electric cars; green electricity generating systems and computers; in steel manufacturing; in glass and light emission materials especially for safety lighting and lasers; in exhaust emission catalysts and supports; catalysts in artificial rubber production; in agriculture and animal husbandry; in health and especially cancer diagnosis and treatment; and in a variety of materials and electronic products essential to modern living. They have the potential to replace toxic chromates for corrosion inhibition, in magnetic refrigeration, a variety of new materials, and their role in agriculture may expand. This review examines their role in sustainability, the environment, recycling, corrosion inhibition, crop production, animal feedstocks, catalysis, health, and materials, as well as considering future uses.

AbstractPure cellulose nanofibers (CNFs) rapidly degrade in soil, limiting their prospective applications in agriculture. We incorporated lignin into CNFs as an antimicrobial and crosslinking agent to control the biodegradation rate. CNFs with different lignin concentrations were prepared by mechanochemical treatment in the presence of choline chloride-urea deep eutectic solvent. These were characterized using conductometric titration, scanning electron microscopy, and FT-IR. The fibers were applied to soil to determine the effect of lignin on soil respiration and nanocellulose degradation, and were used as a substrate for radish and cress seed germination. Modifying the lignin content of the fibers successfully modulated the biodegradation rate in soil. Fibers containing 35% lignin degraded 5.7% in 14 days, while fibers with 20% lignin degraded 20.8% in 14 days. Nanofiber suspensions showed low chemical inhibition for the germination of radish and cress seeds but higher lignin contents reduced the imbibition rate as a seed coating. This study presents the first use of lignin to control the biodegradation rate of cellulose nanofibers in a one-pot, scalable and sustainable system, allowing the advancement of lignocellulose nanofibers for applications such as seed coatings, mulches, and controlled release fertilizers. Graphical Abstract

AbstractThe genes ECERIFERUM1 (CER1) and ECERIFERUM3 (CER3) encode the biosynthesis of alkane waxes, a key component of the plant cuticle. To study the evolution of CER1 and CER3 in a highly diverse group of eucalypts, we performed a genome-wide survey using recently released genome assemblies of 28 Myrtaceae species, with 22 species from the main eucalypt lineage and 6 non-eucalypt Myrtaceae tree species. We manually annotated 250 genes and pseudogenes, identifying a near-ubiquitous single copy of CER3 and 2 to 10 CER1 gene copies per Myrtaceae species. Phylogenetic analysis suggested that copy number variation in eucalypts is due to multiple tandem duplication events, both ancient (shared by all Myrtaceae species studied) and relatively recent (present only in eucalypts). Inter-chromosomal translocations were discovered for both CER1 and CER3, along with recurrent loss of often the same CER1 introns in the WAX2 domain, the domain that is essential for wax production. Despite the varied environments occupied by the eucalypt species in this study, we did not find statistically significant associations between intra-genic structural changes or CER1 copy number and aspects of the environment they occupy (including aridity). The challenge is now to explain the species-specific evolutionary histories that contributed to the observed variation in CER1 and the extent to which it may contribute to the adaptability of eucalypts.

The unmanned aerial vehicle (UAV) based remote sensing has drawn increased attention in precision agriculture. Lightweight optical and thermal sensors have been used widely on UAVs for a range of applications, and have been proposed by some as the best approach to map soil moisture at farm scales. However, passive microwave remote sensing has been widely acknowledged as the most accurate soil moisture mapping technology, and adopted by the soil moisture and ocean salinity and soil moisture active and passive satellite missions. Accordingly, it is postulated that this will also be the best technique for UAV-based near-surface soil moisture remote sensing, overcoming the spatial resolution limitation from low earth orbit altitude. Being so far limited by sensor availability, only a small number of studies have illustrated the potential of UAV-based near-surface soil moisture mapping using L-band microwave radiometers, and there has been no direct comparison with the thermal-optical alternative. To guide the design of future UAV-based soil moisture mapping systems, airborne optical, thermal infrared, and passive microwave observations collected from a scientific aircraft at low altitude over a center-pivot irrigation farm in Tasmania, Australia were used in this study to simulate UAV-based observations, and the performances of the thermal-optical and microwave techniques when compared at 75 m scale. The L-band microwave emission showed a superior sensitivity to near-surface soil moisture, and a higher and more consistent soil moisture retrieval accuracy than thermal-optical, with a root-mean-squared error of 0.05–0.06 m3/m3 and 0.05–0.09 m3/m3, respectively.

AbstractOur understanding of tree stem methane (CH4) emissions is evolving rapidly. Few studies have combined seasonal measurements of soil, water and tree stem CH4 emissions from forested wetlands, inhibiting our capacity to constrain the tree stem CH4 flux contribution to the total wetland CH4 flux. Here we present annual data from a subtropical freshwater Melaleuca quinquenervia wetland forest, spanning an elevational topo‐gradient (Lower, Transitional and Upper zones). Eight field campaigns captured an annual hydrological flood‐dry‐flood cycle, measuring stem fluxes on 30 trees, from four stem heights, and up to 30 adjacent soil or water CH4 fluxes per campaign. Tree stem CH4 fluxes ranged several orders of magnitude between hydrological seasons and topo‐gradient zones, spanning from small CH4 uptake to an emission of ∼203 mmol m−2 d−1. Soil CH4 fluxes were similarly dynamic and shifted from CH4 emission (saturated soil) to uptake (dry soil). In Lower and Transitional zones respectively, tree stem CH4 contribution to the net CH4 ecosystem flux was greatest during flooded conditions (49.9% and 70.2%) but less important during dry periods (3.1% and 28.2%). Minor tree stem emissions from the Upper elevation zone still offset the Upper zone CH4 soil sink capacity by ∼51% during dry conditions. Water table height was the strongest driver of tree stem CH4 fluxes, however tree emissions peaked once the soil was inundated and did not increase with further water depth. This study highlights the importance of quantifying the wetland tree stem CH4 emissions pathway as an important and seasonally oscillating component of wetland CH4 budgets.

The rise of platform capitalism has been instrumental in facilitating capital accumulation at scale through the commodification of previously untradable services and spaces. Digital real estate technology-based platforms or ‘PropTech’ (Property Technology) have transformed how housing is produced, traded, and managed, augmenting existing and creating new housing markets in ways that are still evolving. While ‘home-sharing’ platform Airbnb has become synonymous with ‘peers’ offering residential accommodation online, more traditional forms of house sharing between ‘flat mates’ have also been digitised by global platforms. In this paper we trace the evolution of Australian share housing platform ‘Flatmates.com.au’ from the online equivalent of a campus noticeboard advertising share houses to a sophisticated real estate platform owned by global, PropTech giant Real Estate Advertising ‘REA Group’. In doing so we examine how ‘platform logic’ i.e., converting user-inputted data to information to asset; exponential growth through network expansion and connectivity – has integrated the social practices and relationships defining share households within the global real estate market. The paper contributes to critical literature on the inter-relationships between platform capitalism and housing, focusing specifically on the share housing sector in Australian cities.