Small Size Range Research Articles

The endemic plant species of Ebo Forest, Littoral Region, Cameroon, with a new Critically Endangered cloud forest shrub, Memecylon ebo (Melastomataceae-Olisbeoideae)

SummaryWe emphasise the urgent need to conserve the Ebo forest (Littoral Region, Cameroon), which holds 10 strict endemic plant species and 15 near endemics for a total of 25, a very high number far exceeding the threshold for its recent status as an Important Plant Area (IPA). We describe a further strict endemic species from the Ebo Forest, Memecylon ebo sp. nov. (Melastomataceae-Olisbeoideae), placed in sect. Afzeliana due to its ellipsoid, blue-green fruits. The yellow petals and jade green anther-connectives of M. ebo are unique in the genus Memecylon, which has >400 species ranging overall from Africa to the western Pacific. Memecylon ebo is assessed as Critically Endangered [CR], using the 2012 IUCN standard, due to its small range size and the extremely high and ongoing threats of logging at Ebo and also due to subsequent threats of potential oil palm plantation and mining projects. With the addition of Memecylon ebo, the tally of Critically Endangered plant species recorded from Ebo forest is now the highest of any IPA in Cameroon, equalling that of Ngovayang with 24 CR species.

Pore structure evolution of mortars with manufactured sand aggregate under the influence of aggregate size and water saturation environment

To investigate the effect of aggregate size on pore structure and pore evolution in water saturation of manufactured sand aggregate (MSA) mortars, five MSA mortars with small range of aggregate sizes were prepared and their pore characterization were monitored over 365 days. The findings showed that an increased surface volume ratio (SVR) leads to an increase in total and macroporous porosity, and three pores with different connectivity were quantified using double T2 cutoff method. Moreover, continued hydration by unhydrated cement caused an increase in micropores during the initial stage of service in a water-saturated environment for 365 days, and an increase in macropores at the later stage as a result of enhanced hydraulic solvation, furthermore, solvation was more significant in the mortar with larger SVR to the point where it eventually produced pores larger than 100 μm. This research would provide guidance for the durability evaluation of cement mortars.

Optimization of high-temperature thermal pretreatment conditions for maximum enrichment of lithium and cobalt from spent lithium-ion polymer batteries

Due to their increasingly high demand, lithium-ion batteries (LIBs) will encounter a scarcity of essential resources if recycling is not prioritized. The current pretreatment methods for spent LIBs used in industrial production are inefficient, costly, and hazardous. The study aimed to maximize the yield of lithium and cobalt from the black mass of spent Lithium-ion batteries through an optimized high-temperature thermal pretreatment process, which combined mechanical (direct crushing) and thermal treatments to facilitate the subsequent recovery of these valuable metals. Sieve analysis showed that direct crushing for 2 min resulted in 40.81 % of the anode material in the 4750 + 2500 μm size range, while 5 min of crushing led to a more even distribution, with 28.57 % in the smallest size range (−75 μm). Heat treatment followed by 2 min of crushing concentrated 52.38 % of the anode material in the 4750 + 2500 μm range. For the cathode material, 2 min of direct crushing distributed 24.49 % in the −2500 + 1250 μm range, while 5 min of crushing accumulated 38.80 % in the −75 μm range. Heat treatment and 2 min of crushing resulted in 56.05 % of the cathode material in the −75 μm range, indicating improved liberation. The combination of heat treatment and mechanical treatment effectively liberates and reduces the size of the active materials, resulting in a higher cumulative mass fraction of finer particles (≤630 μm). Heat treatment at 600 °C for 15 min, followed by 2 min of crushing, dissociated current collectors (Al) from the cathode material, minimized the harmful gas emissions and produced fine particles (630 μm) with minimal Al content (0.8 wt%). The optimal heat treatment condition of 600 °C for 35 min achieved complete decomposition of PVDF and enriched 73.49 wt% cobalt and 5.41 wt% lithium in the black mass, superior to previous studies.

Nanofiltration membranes in asymmetric flow field-flow fractionation for improved organic matter size fractionation

Size fractionation of organic matter (OM) by asymmetric flow field-flow fractionation (FFFF) with ultrafiltration (UF) is limited by solute loss and peak resolution, particularly for low molecular weight fractions (<10 kDa). Nanofiltration (NF) with a molecular weight cut-off (MWCO) of ≤1 kDa can achieve significant OM retention and may improve OM fractionation. NF membranes with MWCOs ranging from 0.3 to 3 kDa were used to evaluate the retention and fractionation of nine OMs in the humic, polyphenol, biopolymer, and low molecular weight organic classes in stirred cell NF and FFFF. Membranes with an MWCO of 0.2–0.3 kDa (with a pure water permeability of 5–16 L.m−2.h−1.bar−1) with low OM interaction exhibited high peak recovery and resolution and hence improved OM fractionation. Loose NF (MWCO 3 kDa) exhibited a poor peak recovery because of a high OM loss due to both adhesion and permeation, particularly at high ionic strengths (>10 mM). A mixture of nine types of OM and natural organic matter samples from rivers, swamps and lakes achieved good fractionation with a 0.3 kDa (NF270) membrane at low ionic strength. The performance of NF for the analysis of OM and colloids in the smallest size range (≤1 kDa MW) could be further improved by optimizing the salt composition of the mobile phase and by overcoming the pressure limitations of FFFF channels.

Physiological and molecular effects of contaminants of emerging concerns of micro and nano-size in aquatic metazoans: overview and current gaps in Antarctic species.

Although Antarctica is the most isolated continent on Earth, its remote location does not protect it from the impacts of human activities. Antarctic metazoans such as filter-feeding invertebrates are a crucial component of the Antarctic benthos. They play a key role in the benthic-pelagic carbon flux in coastal areas by filtering particles and planktonic organisms from the sediment-water interface. Due to their peculiar ecological niche, these organisms can be considered a wasp-waist in the ecosystem, making them highly sensitive to marine pollution. Recently, anthropogenic particles such as micro-nanoplastics and manufactured nanoparticles (MNP) have been classified as contaminants of emerging concern (CEC) due to their small size range, which also overlaps with the preferred particle size ingested by aquatic metazoans. Indeed, it has been demonstrated that some species such as Antarctic krill can ingest, transform, and release MNPs, making them newly bioavailable for other Antarctic filter-feeding organisms. Similarly, the production and use of anthropogenic MNP are rapidly increasing, leading to a growing presence of materials, such as nano-sized metal-oxides, in the environment. For these reasons, it is important to provide evidence of the adverse effects of such emerging contaminants at sub-lethal concentrations in environmental risk assessments. These contaminants may cause cascade effects with consequences not only on individuals but also at the community and ecosystem levels. In this review, we discuss the state-of-the-art knowledge on the physiological and molecular effects of anthropogenic MNP in Antarctic aquatic metazoans. We further highlight the importance of identifying early biomarkers using sessile metazoans as sentinels of environmental health.

Understanding regional aerosol deposition in pediatric airways during oral breathing: Insights from computational modeling

While there has been considerable investigation into the deposition of inhaled aerosols in the airways of adults, less is known about where aerosols deposit in the lungs of children. Clinical investigation into aerosol deposition in children is complicated by ethical concerns surrounding ionizing radiation studies in children. To meet the need for non-clinical methods of estimating regional deposition in pediatric airways, multiple in silico models were developed to represent the lungs of girls and boys aged 6, 8, 10 and 12 years. The models were symmetric and used a single-path deterministic approach to calculate aerosol deposition in the airways. Regional deposition estimates were provided for children using a fixed set of controlled breathing patterns before characterizing regional deposition during typical tidal breathing in each age group. Deposition patterns were found to be strongly influenced by inhalation flow rate and aerodynamic particle size. Differences between boys and girls in the fraction of inhaled aerosol depositing were minimal during fixed breathing patterns, with higher deposition in all regions of the younger age groups. However, when breathing patterns were adjusted to represent typical tidal breathing in each age group, age differences in the regional fraction of particles depositing became negligible. Moreover, peak deposition fractions in both the conducting and peripheral airways occurred within a narrow range of aerodynamic particle diameters between 2.4 and 2.6 μm, a smaller size range than for adults. During exposure over a fixed period of time, age-related differences in minute ventilation resulted in a larger aerosol dose depositing in the intrathoracic airways of older children. Such differences suggest that to achieve comparative dosing in this age range, older children should inhale aerosols for a shorter time. These findings provide an improved understanding of regional deposition in pediatric airways and will assist in optimizing regional drug delivery to children.

Detection of microplastics in zebrafish housing systems: Can microplastic background contamination affect the final results of microplastic-related toxicological tests?

Concentrations of microplastics (MPs) were determined in three commonly used zebrafish housing systems to see if their levels could affect the final results of laboratory microplastic-related toxicology tests.MPs have received notable attention in the last few years, and their toxicology tests have also come to the fore. Zebrafish (Danio rerio), kept in fish housing systems, are widely used as models for MPs studies. Most of these systems contain a significant number of parts made of different polymers. As usage and amortization can erode these parts, MPs might appear in the keeping water or the fish body, which may represent a background load and possibly influence the results of microplastic-related toxicological tests.To take representative water samples from systems, two in-situ filtration techniques, a newly developed peristaltic pump-, and a jet pump-driven method were applied. The collected MP particles were analyzed with a Fourier-transform infrared microscope (detection limit 50 μm), and their possible origin was also investigated.The newly developed technique was more sufficient for sampling as it had a higher MPs recovery, especially in the smaller size range. Polyester, polyethylene and polypropylene were the most frequently detected polymers in the examined fish housing systems, the highest detected concentration was 0.31±0.12 particles/liter (0.22±0.16 μg/liter). These values are negligible compared to the literature data reporting enormously high applied MPs concentrations (104 - 2.21 × 108 particles/liter) during toxicology tests. The results also show that some detected MPs did not originate from the systems, their origin was presumed to be external.

Uncertainty in consensus predictions of plant species' vulnerability to climate change

AbstractAimVariation in spatial predictions of species' ranges made by various models has been recognized as a significant source of uncertainty for modelling species distributions. Consensus approaches that combine the results of multiple models have been employed to reduce the uncertainty introduced by different algorithms. We evaluate how estimates of habitat suitability, projected using species distribution models (SDMs), varied among different consensus methods relative to the variation introduced by different global climate models (GCMs) and representative concentration pathways (RCPs) used for projection.LocationCalifornia Floristic Province (California, US portion).MethodsWe modelled the current and future potential distributions of 82 terrestrial plant species, developing model predictions under different combinations of GCMs, RCPs, time periods, dispersal assumptions and SDM consensus methods commonly used to combine different species distribution modelling algorithms. We assessed how each of these factors contributed to the variability in future predictions of species habitat suitability change and aggregate measures of proportional change in species richness. We also related variability in species‐level habitat change to species' attributes.ResultsAssuming full dispersal capacity, the variability between habitat predictions made by different consensus methods was higher than the variability introduced by different RCPs and GCMs. The relationships between species' attributes and variability in future habitat predictions depended on the source of uncertainty and dispersal assumptions. However, species with small ranges or low prevalence tended to be associated with high variability in range change forecasts.Main ConclusionsOur results support exploring multiple consensus approaches when considering changes in habitat suitability outside of species' current distributions, especially when projecting species with low prevalence and small range sizes, as these species tend to be of the greatest conservation concern yet produce highly variable model outputs. Differences in vulnerability between diverging greenhouse gas concentration scenarios are most readily observed for end‐of‐century time periods and within species' currently occupied habitats (no dispersal).

Quantifying the electric service panel capacities of California's residential buildings

This study seeks to quantify the size distribution of existing installed electrical service panels within California's residential buildings, a potentially significant barrier to future decarbonization efforts. A large sample of historical building permit data was collected for municipalities throughout the state, from which permitted panel upgrades were extracted and analyzed. These data were used to develop a method for estimating panel capacities that incorporates information about historical code requirements for panel sizing in new construction with a statewide database of parcel-level building attributes. Overall, we find that 3% of single-family (SF) and 10% of multi-family (MF) properties in California have panels in the smallest size range, which will most likely require upgrades. However, 32% of SF and 59% of MF properties have panels of intermediate size, which will likely require the addition of load management systems to support comprehensive electrification. Future panel upgrade needs are expected to be more acute within disadvantaged communities, where the proportion of SF homes with the smallest-sized panels is 4x that in more affluent neighborhoods. We discuss the implications of these and other results within the context of existing and planned future state policies related to residential electrification.

Dispersal‐related plant traits are associated with range size in the Atlantic Forest

AbstractAimThe efficiency of animal‐mediated seed dispersal is threatened by the decline of animal populations, especially in tropical forests. We hypothesise that large‐seeded plants with animal‐mediated dispersal tend to have limited geographic ranges and face an increased risk of extinction due to the potential decline in seed dispersal by large‐bodied fruit‐eating and seed‐dispersing animals (frugivores).LocationAtlantic Forest, Brazil, South America.TaxonAngiosperms.MethodsFirst, we collected dispersal‐related traits (dispersal syndrome, fruit size, and seed size), growth form (tree, climber, and other) and preferred vegetation type (open and closed) data for 1052 Atlantic Forest plant species. Next, we integrated these with occurrence records, extinction risk assessments, and phylogenetic trees. Finally, we performed phylogenetic generalised least squares regressions to test the direct and interactive effects of dispersal‐related traits and vegetation type on geographical range size.ResultsLarge‐seeded species had smaller range sizes than small‐seeded species, but only for species with animal‐mediated dispersal, not for those dispersed by abiotic mechanisms. However, plants with abiotic dispersal had overall smaller range sizes than plants with animal‐mediated dispersal. Furthermore, we found that species restricted to forests had smaller ranges than those occurring in open or mixed vegetation. Finally, at least 29% of the Atlantic Forest flora is threatened by extinction, but this was not related to plant dispersal syndromes.Main ConclusionsLarge‐seeded plants with animal‐mediated dispersal may be suffering from dispersal limitation, potentially due to past and ongoing defaunation of large‐bodied frugivores, leading to small range sizes. Other factors, such as deforestation and fragmentation, will probably modulate the effects of dispersal on range size, and ultimately extinction. Our study sheds light on the relationship between plant traits, mutualistic interactions, and distribution that are key to the functioning of tropical forests.

Drift drives the evolution of chromosome number II: The impact of range size on genome evolution in Carnivora.

Chromosome number is a fundamental genomic trait that is often the first recorded characteristic of a genome. Across large clades, a common pattern emerges: many or even most lineages exhibit relative stasis, while a handful of lineages or species exhibit striking variation. Despite recent developments in comparative methods, most of this heterogeneity is still poorly understood. It is essential to understand why some lineages have rapid rates of chromosome number evolution, as it can impact a variety of other traits. Previous research suggests that biased female meiotic drive may shape rates of karyotype evolution in some mammals. However, Carnivora exhibits variation that this female meiotic drive model cannot explain. We hypothesize that variation in effective population size may underlie rate variation in Carnivora. To test this hypothesis, we estimated rates of fusions and fissions while accounting for range size, which we use as a proxy for effective population size. We reason fusions and fissions are deleterious or underdominant and that only in lineages with small range sizes will these changes be able to fix due to genetic drift. In this study, we find that the rates of fusions and fissions are elevated in taxa with small range sizes relative to those with large range sizes. Based on these findings, we conclude that 1) naturally occurring structural mutations that change chromosome number are underdominant or mildly deleterious, and 2) when population sizes are small, structural rearrangements may play an important role in speciation and reduction in gene flow among populations.

Spatial characteristics and ecological wisdom of Amdo Tibetan traditional dwellings in western Sichuan

ABSTRACT Amdo Tibetans are an important part of the three major Tibetan areas in western Sichuan. Their production and life style rooted in the Ruoergai grassland pastoral area is significantly different from that of Kangba Tibetans and Jiarong Tibetans, which are widely distributed in the valley areas. However, due to the relatively small population size and distribution range, there is still a lack of research on the space of multi-Tibetan settlements in western Sichuan, which makes the unique spatial characteristics of grassland dwellings and their generation logic unclear. Based on a large number of literature studies and field investigations, this paper systematically analyzes its location pattern, spatial layout and material application from the perspective of ecological wisdom through spatial analysis, comparative analysis and other methods. The results show that there are obvious differences in spatial form between the Tibetan dwellings in Anduo grassland in western Sichuan and the Tibetan settlements in Kangba and Jiarong. The scattered siting model is used to cope with the impact of bad climate and the characteristics of widely dispersed production factors. The diversified, specialized and open yard space layout is adapted to the production mode of pastoral areas. Local materials such as manure are used to build settlement space according to local conditions. This study reveals the spatial characteristics and environmental adaptation wisdom of multi-Tibetan grassland dwellings in western Sichuan, complements and improves the Tibetan research system and content in western Sichuan, and provides theoretical guidance for the healthy and sustainable development of multi-Tibetan settlements in western Sichuan.

CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer

Kenics static mixers (KSM) are extensively used in industrial mixing–reaction processes by virtue of high mixing efficiency, low power homogenization and easy continuous production. Resolving liquid droplet size and its distribution and thus revealing the dispersion characteristics are of great significance for structural optimization and process intensification in the KSM. In this work, a computational fluid dynamics–population balance model (CFD–PBM) coupled method is employed to systematically investigate the effects of operating conditions and structural parameters of KSM on droplet size and its distribution, to further reveal the liquid–liquid dispersion characteristics. Results indicate that higher Reynolds numbers or higher dispersed phase volume fractions increase energy dissipation, reducing Sauter mean diameter (SMD) of dispersed phase droplets and with a shift in droplet size distribution (DSD) towards smaller size. Smaller aspect ratios, greater blade twist and assembly angles amplify shear rate, leading to smaller droplet size and a narrower DSD in the smaller range. The degree of impact exerted by the aspect ratio is notably greater. Notably, mixing elements with different spin enhance shear and stretching efficiency. Compared to the same spin, SMD becomes 3.7–5.8 times smaller in the smaller size range with a significantly narrower distribution. Taking into account the pressure drop and efficiency in a comprehensive manner, optimized structural parameters for the mixing element encompass an aspect ratio of 1–1.5, a blade twist angle of 180°, an assembly angle of 90°, and interlaced assembly of adjacent elements with different spin. This work provides vital theoretical underpinning and future reference for enhancing KSM performance.

Rapoport's rule explains the range size distribution of butterflies along the Eastern Himalayan elevation gradient

AbstractUnderstanding elevational range size distribution of organisms can provide valuable insights on biogeographic pattern of species and their conservation. Rapoport's rule posits that the elevational range size of species increases with increasing elevation. However, the validity of this rule is often questioned due to variations in methodologies across studies and inconsistencies among different groups of organisms. In this study, we examined the elevational range size distribution of butterflies in the Eastern Himalaya, and assessed the applicability of Rapoport's rule using different approaches, which perhaps is the first of its kind in the Himalaya. We sampled butterflies along the elevational gradient of 16 elevational bands (300–3300 m) using point count method along the transect. The sampled butterflies were grouped into various sub‐groups based on family, biogeographic affinity, and larval feeding pattern. We found that the majority of the butterfly species (total as well as sub‐groups) had small range sizes, and their elevational range distribution showed support for the Rapoport's rule. Increase in variation in temperature as measured by temperature seasonality and mean annual temperature range were the most important predictors of range size distribution pattern of the overall butterfly community. However, the relationship between range size and climatic variability differed among various sub‐groups implying that the perceived pattern may vary even within the species of the same taxon.Abstract in Nepali is available with online material.

The environmental conditions of endemism hotspots shape the functional traits of mammalian assemblages.

Endemic (small-ranged) species are distributed non-randomly across the globe. Regions of high topography and stable climates have higher endemism than flat, climatically unstable regions. However, it is unclear how these environmental conditions interact with and filter mammalian traits. Here, we characterize the functional traits of highly endemic mammalian assemblages in multiple ways, testing the hypothesis that these assemblages are trait-filtered (less functionally diverse) and dominated by species with traits associated with small range sizes. Compiling trait data for more than 5000 mammal species, we calculated assemblage means and multidimensional functional metrics to evaluate the distribution of traits across each assemblage. We then related these metrics to the endemism of global World Wildlife Fund ecoregions using linear models and phylogenetic fourth-corner regression. Highly endemic mammalian assemblages had small average body masses, low fecundity, short lifespans and specialized habitats. These traits relate to the stable climate and rough topography of endemism hotspots and to mammals' ability to expand their ranges, suggesting that the environmental conditions of endemism hotspots allowed their survival. Furthermore, species living in endemism hotspots clustered near the edges of their communities' functional spaces, indicating that abiotic trait filtering and biotic interactions act in tandem to shape these communities.

Multiscale Porosity Microfluidics to Study Bacterial Transport in Heterogeneous Chemical Landscapes.

Microfluidic models are proving to be powerful systems to study fundamental processes in porous media, due to their ability to replicate topologically complex environments while allowing detailed, quantitative observations at the pore scale. Yet, while porous media such as living tissues, geological substrates, or industrial systems typically display a porosity that spans multiple scales, most microfluidic models to date are limited to a single porosity or a small range of pore sizes. Here, a novel microfluidic system with multiscale porosity is presented. By embedding polyacrylamide (PAAm) hydrogel structures through in-situ photopolymerization in a landscape of microfabricated polydimethylsiloxane (PDMS) pillars with varying spacing, micromodels with porosity spanning several orders of magnitude, from nanometers to millimeters are created. Experiments conducted at different porosity patterns demonstrate the potential of this approach to characterize fundamental and ubiquitous biological and geochemical transport processes in porous media. Accounting for multiscale porosity allows studies of the resulting heterogeneous fluid flow and concentration fields of transported chemicals, as well as the biological behaviors associated with this heterogeneity, such as bacterial chemotaxis. This approach brings laboratory studies of transport in porous media a step closer to their natural counterparts in the environment, industry, and medicine.

Dorsal CA1 lesions of the hippocampus impact mating tactics in prairie voles by shifting non-monogamous males' use of space to resemble monogamous males.

Alternative mating tactics within mating systems are characterized by discrete patterns of spatio-temporal overlap with same-and opposite-sex conspecifics and mating-relevant outcomes. Socially monogamous "residents" maintain relatively small home range sizes, have territories that almost exclusively overlap with their mating partners, and are more likely to produce offspring than non-bonded "wandering" conspecifics. Because mating tactics appear to be so closely tied to patterns of space use, differences in spatial cognitive abilities might differentially impact individual males' decisions to adopt a particular mating tactic and/or how efficient they are within their chosen mating tactic. Yet few studies have considered how the hippocampus, a brain region important for encoding cognitive maps and for processing contextual information, might impact how individuals adopt mating tactics or the spatio-temporal behaviors closely associated with them. We assessed the impact of lesions to the dorsal CA1 (dCA1) region of the hippocampus on male prairie vole space use, reproductive success, and mating tactics in semi-natural outdoor field conditions. Interestingly, dCA1 lesions did not impact the proportion of males that adopted resident or wandering mating tactics, and dCA1 lesions did not impact a male's ability to form a pair bond in the lab. In contrast, we found that lesioning the dCA1 shifted the home range size of reproductively successful and unsuccessful males. Furthermore, we found that patterns of space use among residents were unaffected by dCA1 lesions, whereas wanderers with dCA1 lesions showed pronounced reductions of their space use habits and resembled non-lesioned residents. Collectively, our study supports the hypothesis that wanderer male prairie voles rely on dCA1-mediated spatial cognition to navigate their world in a way that resident males do not. Such differences might have implications for how individuals efficiently attract and defend mates, obtain resources, defend territories, and outcompete rivals.

Soil colloids as binding agents in the formation of soil microaggregates in wet-dry cycles: A case study for arable Luvisols under different management

In the hierarchical model of soil aggregates, small soil microaggregates (small SMA; <20 μm) are often considered to be fundamental building units at the micron scale. Below which, soil colloids (<1 µm) have recently been proposed as binding agents of (micro)aggregates. However, the way in which soil colloids contribute to the formation and stability of soil micro- and macroaggregates remains largely unknown. For clarification, we evaluated potential impacts of the colloidal content, particularly the <450 nm colloids, on the aggregation of small SMA. Free water stable small SMA and <450 nm colloids were isolated from Ap-horizons of Stagnic Luvisols under different management (cropped and bare fallow). The size-resolved elemental composition of the <450 nm colloids was analyzed by asymmetric flow field-flow fractionation in combination with an inductively coupled plasma mass spectrometer and an organic carbon detector. To vary the colloidal content in small SMA, (1) suspensions containing different amounts of <450 nm colloids were added in small SMA, or (2) <1 µm colloids were removed from small SMA by centrifugation. In the maximum colloidal addition treatment, the mass ratios of added colloids to small SMA were 3.0 and 5.1 wt% for the cropped and bare fallow soil samples, respectively. Aggregation of small SMA with different colloidal amounts was performed in three successive wet-dry cycles. Afterwards, the size distribution of the resulting aggregates was measured by laser diffraction. Our results indicated that, in wet-dry cycles, colloids were important binding agents for the formation of SMA. Their presence, especially those <450 nm, was likely to support the formation of solid bridges during drying at particle contacts of 1–10 µm small SMA, favoring hereby SMA build-up in a relatively small size range of 1–40 µm. In contrast, the absence of <1 μm colloids in small SMA led to a preferential generation of relatively large aggregates in wet-dry cycles, i.e., typically with sizes >40 μm up to 1700 μm in maximum. Our study on aggregation in wet-dry cycles revealed that the colloidal content has a controlling effect on the size distribution of resulting aggregates by acting as a binding agent and provides hereby new insights into the evolvement of aggregate hierarchy in soils.

Scalable phylogenetic Gaussian process models improve the detectability of environmental signals on local extinctions for many Red List species

Abstract Conservation biologists have a daunting task of understanding the causes of species decline associated with anthropogenic factors and predicting the extinction risk of a growing number of endangered species. By reducing variances of estimates with information on closely related species, phylogenetic information among species can bridge gaps in information on species with small range sizes when modelling large numbers of endangered species. However, modelling many species with the Gaussian process (GP), which underlies the evolutionary process of phylogenetic random effects, remains a challenge owing to the computational burden in estimating the large variance–covariance matrix. Here, we applied a phylogenetic generalised mixed model with random slopes and random intercepts to 1010 endangered vascular plant taxa in Japan following phylogenetic GPs implemented by nearest neighbour GP (NNGP) approximation. NNGP enables flexibility in changing the proximity on the phylogenetic tree of species from which information is borrowed to reduce the variances of estimates with a realistic computational burden. We evaluated the effectiveness of phylogenetic models by comparing the predictive performance and descriptive power of phylogenetic and non‐phylogenetic models and identified the anthropogenic factors contributing to the decline of each of the studied endangered species. We found that the model with phylogenetic information had better prediction performance than the model without phylogenetic information. The results showed that across all explanatory variables, the phylogenetic model could detect interspecific differences in response to environmental factors in a number of species more clearly. Combined with the phylogenetic signal results, we could also detect a phylogenetic bias in the species that could benefit from the positive effects of protected areas but reduce the local extinctions of 95% of all studied taxa. In conclusion, our model, considering phylogenetic information with NNGP, allows the elucidation of factors causing the decline of many endangered species. In future analyses, the estimation of extinction probability linked to environmental change might be applied to future climate–land use scenarios, advancing the comprehensive assessment of biodiversity degradation and threats to species at multiple scales.

Study on scale effect and particle crushing characteristics of continuously graded coarse-grained soil

The scale effect is an inevitable engineering challenge in dam construction, and the scale test is an effective means to characterize the dam material properties. In this article, the scale effect of the large coarse-grained soil is investigated based on physical and numerical tests. Firstly, the indoor and field compression test apparatuses are optimized to rectify the effect of barrel sidewall friction on the compressibility modulus during the tests. Then, the sample preparation standard for different scaled samples is determined by large-scale relative density tests in the field. Finally, based on indoor and field large-scale compression tests, the variation of the scale effect is investigated, and the particle crushing characteristics of the continuously graded aggregate sample are analyzed. The crushing characteristics of the continuously graded aggregate sample differ from those of the single-particle and the single size-group aggregate sample (a small range of particle sizes). Compression tests of the single-particle, single size-group aggregate, and continuously graded aggregate sample are characterized by overall splitting, overall splitting and local crushing, and local or angular crushing, respectively. The coordination number is the main reason for the difference in crushing characteristics of different test samples. The relationship between different particle sizes and strengths of continuously graded aggregate sample is investigated. The results of the study can provide a reference for recognizing the scale effect of large coarse-grained soils and evaluating compaction quality in the field.