Size Sorting Research Articles

Pore Characteristics of the Fine‐Grained Tight Reservoirs in the Yabulai Basin, Northwestern China

This work investigated the pore structure characteristics and reservoir features of the finegrained tight reservoirs in the lower member of the Xinhe Formation (J2x1) in the Xiaohu subsag, Yabulai Basin based on core samples through various techniques. Interbedded silt/fine sandstones and mudstones are developed in the study area. Scanning electron microscopy (SEM) images were used to delineate different types of pores, including primary intergranular pores, secondary intergranular and intragranular pores, organic pores and fractures. The pore types were distinguished by pore size, pore area, location and formation process. The pore radii of the fine‐grained rocks range from 1 nm to 1.55 μm, mainly concentrated between 5 and 300 nm by low pressure N2 adsorption and MICP analyses. The pore structure parameters of pore throat size and pore throat sorting coefficient are both positively correlated with porosity, while pore throat sorting coefficient has a negative correlation with permeability. The pore structures of the studied samples are much related to the mineral type and content and grain size, followed by TOC content. In these rocks with relatively low TOC and low maturity, the rigid minerals protect pores with pressure shadow from collapse, and dissolution‐related pores contribute a lot to inorganic porosity. In contrast, these rocks with abundant TOC contain a large number of organic pores. The permeability of the fine‐grained tight reservoir is mainly dominated by larger pore throats, while a large number of small pores (mostly <0.1 μm) contribute considerably to porosity. These results have deepened our understanding of the interbedded fine‐grained tight reservoirs and can be applicable to fine‐grained reservoirs in a similar setting.

Application of the extended quadrature method of moments as a multi-moment parameterization scheme for raindrops sedimentation

In numerical weather prediction models, previous approaches have employed bulk parameterization schemes based on presumed-number-density-functions or quadrature methods of moments (QMOM). In the present work, a new parameterization based on the extended quadrature method of moments (EQMOM) introduced in Yuan et al. (2012) is applied to the case of pure sedimentation of rain drops (one-dimensional “rain-shaft” test case). In EQMOM, the drop size distribution is represented by a weighted sum of kernel density functions, combining elements of quadrature and presumed functional form methods. In cloud microphysics, moment parameterization is frequently based on Gamma distributions, which guided the choice of the kernel shape employed here. EQMOM allows inclusion of a number of prognostic moments in the method (e.g. M(0)-M(6)), which improves flexibility in the representation of a continuous size distribution. QMOM and EQMOM up to order 3 were applied in two drop sedimentation test cases previously presented in the literature, in which initial states consist of different cloud heights and drop size distribution shapes. Results were compared to a spectral reference model using a number of transported bin sizes showing good agreement. The analysis was focused in the sedimentation induced errors obtained by the different approaches. In QMOM, size sorting due to different fall velocities generates step patterns in the moment profiles. With EQMOM, on the other hand, these artifacts are significantly suppressed. Furthermore, predictions of the number concentration, total liquid content, radar reflectivity, mass mean diameter and rain rates are shown to be greatly improved when EQMOM is employed. Quantitatively, EQMOM is capable of reducing global error measures by nearly one order of magnitude, when compared to results obtained by previous methods in a common benchmark, showing the great potential of the method in the field of meteorology.

Particle size distributions in chondritic meteorites: Evidence for pre-planetesimal histories

Magnesium-rich silicate chondrules and calcium-, aluminum-rich refractory inclusions (CAIs) are fundamental components of primitive chondritic meteorites. It has been suggested that concentration of these early-formed particles by nebular sorting processes may lead to accretion of planetesimals, the planetary bodies that represent the building blocks of the terrestrial planets. In this case, the size distributions of the particles may constrain the accretion process. Here we present new particle size distribution data for Northwest Africa 5717, a primitive ordinary chondrite (ungrouped 3.05) and the well-known carbonaceous chondrite Allende (CV3). Instead of the relatively narrow size distributions obtained in previous studies (Ebel et al., 2016; Friedrich et al., 2015; Paque and Cuzzi, 1997, and references therein), we observed broad size distributions for all particle types in both meteorites. Detailed microscopic image analysis of Allende shows differences in the size distributions of chondrule subtypes, but collectively these subpopulations comprise a composite “chondrule” size distribution that is similar to the broad size distribution found for CAIs. Also, we find accretionary ‘dust’ rims on only a subset (∼15–20%) of the chondrules contained in Allende, which indicates that subpopulations of chondrules experienced distinct histories prior to planetary accretion. For the rimmed subset, we find positive correlation between rim thickness and chondrule size. The remarkable similarity between the size distributions of various subgroups of particles, both with and without fine grained rims, implies a common size sorting process. Chondrite classification schemes, astrophysical disk models that predict a narrow chondrule size population and/or a common localized formation event, and conventional particle analysis methods must all be critically reevaluated. We support the idea that distinct “lithologies” in NWA 5717 are nebular aggregates of chondrules. If ≥cm-sized aggregates of chondrules can form it will have implications for planet formation and suggests the sticking stage is where the preferential size physics is operating.

Tuning Morphology and Defect Density in Self-Assembled Thin-Films of Solvent-Exfoliated WSe2 for Photoelectrochemical Hydrogen Production

The layered semiconducting transition metal dichalcogenides can be exfoliated into atomically-thin 2D sheets offering promising opto-electronic characteristics for application in solar energy conversion. However, the challenges to fabricate high-quality thin films of these 2D sheets using scalable and cost-effective methods limit their practical application. Here we present novel solution-based approaches for large-area semiconducting films of liquid exfoliated WSe2 with controllable flake alignment and defect density, which is leveraged to advance the understanding of the morphological and structural factors on the optoelectronic performance in devices. Specifically, we develop a thin film self-assembly method employing spatial confinement of WSe2 nanoflakes which affords overlapping-free morphology and superior charge transfer character over films with aggregations.[1, 2] The critical roles of the flake edge density, flake lateral size and thickness on the photogenerated charge transport and transfer are established by both experimental (by solution-based flake size sorting) and theoretical (by anisotropic charge transport simulation) routes.[3] In addition, we recently develop approaches to reduce charge recombination at internal crystal defects and surface dangling bonds by applying pre-annealing and surfactant treatments, respectively, which affords a considerable improvement that represents a new benchmark for the performance of solution-processed WSe2. Solar photocurrents for H2 evolution up to 4.0 mA cm–2 (at 0V vs RHE, AM 1.5G illumination), and internal quantum efficiency over 60% are reported for 10 nm thick WSe2 photoelectrodes. [1] Yu X.; Prevot, M. S.; Guijarro, N.; Sivula, K. Nat. Commun. 2015, 6, 7596. [2] Yu X.; Prévot, M. S.; Sivula, K. Chem. Mater. 2014, 26, 5892. [3] Yu, X.; Sivula, K. Chem. Mater. 2017, 29, 6863.

Thermophoresis-Controlled Size-Dependent DNA Translocation through an Array of Nanopores.

Large arrays of nanopores can be used for high-throughput biomolecule translocation with applications toward size discrimination and sorting at the single-molecule level. In this paper, we propose to discriminate DNA length by the capture rate of the molecules to an array of relatively large nanopores (50-130 nm) by introducing a thermal gradient by laser illumination in front of the pores balancing the force from an external electric field. Nanopore arrays defined by photolithography were batch processed using standard silicon technology in combination with electrochemical etching. Parallel translocation of single, fluorophore-labeled dsDNA strands is recorded by imaging the array with a fast CMOS camera. The experimental data show that the capture rates of DNA molecules decrease with increasing DNA length due to the thermophoretic effect of the molecules. It is shown that the translocation can be completely turned off for the longer molecule using an appropriate bias, thus allowing a size discrimination of the DNA translocation through the nanopores. A derived analytical model correctly predicts the observed capture rate. Our results demonstrate that by combining a thermal and a potential gradient at the nanopores, such large nanopore arrays can potentially be used as a low-cost, high-throughput platform for molecule sensing and sorting.

An Early Triassic (Dienerian) microgastropod assemblage from the Salt Range, Pakistan and its implication for gastropod recovery from the end-Permian mass extinction

A single limestone sample from the Early Triassic (late Dienerian) of the Salt Range in Pakistan has yielded numerous small gastropods (smaller 2 mm), few bivalves and abundant ammonoids. The limestone is interpreted as a tempestite. Many of the gastropods are extremely well-preserved including protoconch preservation and micro-ornaments. Five species of gastropods are present: (1) isolated larval shells representing a neritimorph taxon of the family Trachyspiridae, (2) early juvenile and larval specimens of the caenogastropod Strobeus pakistanensis, (3) the new caenogastropod species Coelostylina hydrobifomis Nutzel & Ware, (4) the new heterobranch genus and species Eographis microlineata Ntitzel & Ware representing the earliest occurrence of the extant family Hyalogyrinidae (Valvatoidea), (5) the heterobranch Sinuarbullina sp., a genus which originates in the Early Triassic and has also been reported from China, Spitsbergen and the US. Three genera (trachyspirid. Strobeus and Coelostylina) represent survivors from the end-Permian mass extinction whereas Eographis and Sinuarbullina have their earliest known occurrence in the Early Triassic. Eographis is the first Early Triassic genus for which coaxial larval heterostrophy is shown. Together with the Devonian genus Palaeocarboninia and the Carboniferous genus Heteroaclisina, it witnesses a high age of Ectobranchia (living families Hyalogyrinidae, Valvatidae. Comirostridae and Xylodisculidae). This supports the assumption that this group is the first extant offshoot of the Heterobranchia. The studied assemblage is strongly dominated by Strobeus pakistanesis. The small size of the gastropods reflects their ontogenetic stage (early juvenile and larval shells) as well as a small adult size in some of the species. Most of the present gastropods had planktotrophic larval development providing further evidence against the hypothesis that the end-Permian mass extinction event selected against larval planktotrophy. Failure to grow to a larger size or to perform metamorphosis suggests unfavourable living conditions in the source community probably due to oxygen deficiency prior to transport by storm. Size sorting is seen as less likely because the limestone is poorly sorted with relatively large ammonoids being present in considerable numbers. The studied sample yielded also three bivalve taxa amongst them two species representing the genera Leptochondria and Crittendenia.

Impact of sequence stratigraphy, depositional facies, diagenesis and CO2 charge on reservoir quality of the lower cretaceous Quantou Formation, Southern Songliao Basin, China

Abstract The fourth member of the Lower Cretaceous Quantou Formation in Southern Fuxin Uplift zone of the Southern Songliao Basin is typical tight oil reservoir which has recently been explored and produced. For effective exploration and development, the evaluation and control factors of the reservoir quality of the K1q4 sandstones should be thoroughly studied. The study focused on the control of the combination of sequence stratigraphy, depositional facies and diagenesis on the reservoir quality, and identified the impact of CO2 charging, based on the core and thin section observation, XRD, SEM, fluid inclusion and isotope testing and analysis. The fourth member of the Lower Cretaceous Quantou Formation consists of lowstand system tracts (LST), transgressive system tracts (TST) and highstand system tracts (HST). The K1q4 sandstones were mostly deposited in distributary channels and crevasse splays of a delta plain within the LST and TST, and underwater distributary channels and sheet sands of a delta front within the HST. The K1q4 sandstones, mostly silt to medium grained, medium to well sorted, and are mostly lithic arkoses and feldspathic litharenites, have undergone significantly diagenetic alterations, such as compaction, quartz cementation, unstable grains (feldspar and volcanic fragments) dissolution, carbonate cementation and clay minerals cementation. The reservoir quality of the K1q4 sandstones are poor with low porosity and permeability, showing variations among the different system tracts and depositional facies, and are influenced by the charging of CO2 and controlled by the combination of sequence stratigraphy, depositional facies and diagenesis. The sandstones with high reservoir quality are mostly deposited in high energy environments, including the (underwater) distributary channel sandstones, especially the LST distributary channel sandstones with the best reservoir quality among the LST, TST and HST sandstones, which can be ascribed to larger grain size and better sorting resulting in larger intergranular pore space after compaction, and less content of carbonate cements, illite and mixed-layer I/S, and more pore-lining chlorite and more effectively dissolution. The poor reservoir quality of sandstones from crevasse splay and sheet sand is due to the small grain size and bad sorting which resulted in extensive compaction and the resulting weak dissolution. The charging of CO2 has dual impact on the reservoir quality of the K1q4 sandstones. The CO2 charging can induce the dissolution of unstable detrital grains and the precipitation of dawsonite. The former create new secondary pore space, while the latter occupy the intergranular pore space. The CO2 charging is harmful to the reservoir quality when the dawsonite content exceeds a threshold of 5%.

Soil organic carbon and mineral interactions on climatically different hillslopes

Climate and topography have been widely recognized but studied separately as important factors controlling soil organic carbon (SOC) dynamics. Subsequently, the significance of their interplay in determining SOC storages and their pools is not well understood. Here we examined SOC storages and SOC-mineral interactions along two hillslope transects in differing climate zones (MAP = 549 mm in semi-arid eucalyptus savannah vs. 816 mm in temperate eucalyptus forest) in southeastern Australia. On eroding slopes, SOC inventories were twice as large at the wetter site (4.5 ± 0.6 vs. 2.3 ± 0.9 kg m−2), whereas depositional soils had similar SOC inventories at both locations (7.5 ± 2.0 vs.7.0 ± 2.2 kg m−2). On eroding slopes, carbon concentrations of the mineral-associated SOC fraction (<250 μm and >2.0 g cm−3) increased by ~50% with increasing rainfall, which was also positively correlated to abundances of clay minerals and pedogenic iron oxides. Within individual hillslopes, carbon concentrations of the mineral-associated SOC fraction doubled from eroding to depositional soils at the drier site, but no topographic trend was observed at the wetter site. The effects of topography on SOC inventories and mineral-associated SOC were more strongly expressed under the drier climate, where vegetation was sparser and soil erosion involved mineral grain size sorting. Our results demonstrate that SOC pools and their interactions with minerals are dependent on topographic locations, emphasizing the need to include geomorphic data when assessing climatic controls of SOC.

Loess in Italy: Genesis, characteristics and occurrence

There is currently a renewed interest in loess genesis and occurrence in Italy. Well-known loess profiles in northern Italy have been re-examined, and previously unknown loess deposits in central and southern Italy have been reported. This work combines a meta-analysis of published data with new data, presented here for the first time, to provide the state of the art on the spatial distribution, characteristics, genesis, and deposition ages of loess in Italy. A database of 98 soil horizons from 91 soil profiles was created and made available. It stores information on soils formed from loess or containing layers that show admixture of loess. Soil data include the source of information, the topographic, geomorphological and geological setting, kind of parent material and land use, main soil horizon properties as described in the field, soil classification, particle size distribution and chemical data.Loess is reported from almost all regions of Italy. It is generally pedogenized throughout the entire loess body and forms the parent material of deep and complex soil profiles. The thickness of the loess deposits varies from a few decimeters to a few meters; pedogenesis and local reworking partially change the original loess characteristics. In this study, we propose a set of parameters that help recognizing loess in soils: particle size distribution and sorting, geomorphological setting, pedostratigraphic position, shape of the grains under optical and scanning electron microscope (SEM), and soil-micromorphological characteristics.The ages of the loess deposits range between 70 ka BP and 18 ka BP. There are also a number of samples that have been dated to the Holocene. The meta-analysis suggests that climate is not the only driver of loess deposition in Italy; geomorphological instability and human disturbance, as well as the influence of Saharan dust, most likely played major roles, too.This study demonstrates that loess is much more widespread in Italy than previously estimated. Yet, further research on the spatial and temporal distribution of loess deposition across the Mediterranean region is needed to better understand its genesis, sources and trajectories, periods of enhanced loess formation, and the role of loess deposits in ecosystem functioning and resilience.

Climate controls on coupled processes of chemical weathering, bioturbation, and sediment transport across hillslopes

AbstractMost hillslope studies examining the interplay between climate and earth surface processes tend to be biased towards eroding parts of landscapes. This limitation makes it difficult to assess how entire upland landscapes, which are mosaics of eroding and depositional areas, evolve physio‐chemically as a function of climate. Here we combine new soil geochemical data and published 10Be‐derived soil production rates to estimate variations in chemical weathering across two eroding‐to‐depositional hillslopes spanning a climate gradient in southeastern Australia. At the warmer and wetter Nunnock River (NR) site, rates of total soil (–3 to –14 g m‐2 yr‐1; negative sign indicates mass loss) and saprolite (–18 to –32 g m‐2 yr‐1) chemical weathering are uniform across the hillslope transect. Alternatively, the drier hillslope at Frog's Hollow (FH) is characterized by contrasting weathering patterns in eroding soils (–30 to –53 g m‐2 yr‐1) vs. depositional soils (+91 g m‐2 yr‐1; positive sign indicates mass addition). This difference partly reflects mineral grain size sorting as a result of upslope bioturbation coupled with water‐driven soil erosion, as well as greater vegetative productivity in moister depositional soils. Both of these processes are magnified in the drier climate. The data reveal the importance of linking the erosion–deposition continuum in hillslope weathering studies in order to fully capture the coupled roles of biota and erosion in driving the physical and chemical evolution of hillslopes. Our findings also highlight the potential limitations of applying current weathering models to landscapes where particle‐sorting erosion processes are active. Copyright © 2018 John Wiley &amp; Sons, Ltd.

Effect of increasing the level of alfalfa hay in finishing beef heifer diets on intake, sorting, and feeding behavior.

Eight rumen cannulated Simmental heifers (BW = 281.4 ± 7.28 kg) were randomly assigned to one of four experimental treatments in a 4 × 4 replicated Latin square design to ascertain the effects of increasing levels of alfalfa hay on intake, sorting, and feeding behavior in comparison to barley straw as forage source. Treatments tested were four total mixed rations with: 1) 10% barley straw (10BS) with 7.0% NDF from forage, 2) 13% alfalfa hay (13AH) and less NDF from forage (5.7%) than 10BS, 3) 16% alfalfa hay (16AH) and the same NDF from forage (7.0%) as 10BS, and 4) 19% alfalfa hay (19AH) and more NDF from forage (8.3%) than 10BS. Each experimental period consisted of 3 wk for adaptation and 1 wk for sampling. Increasing the proportion of alfalfa hay in the diet linearly increased (P < 0.05) total DMI, CP intake, water consumption, intake of long, medium and fine particle size, extent of sorting of fine particle size, and time spent rumination, but linearly decreased (P < 0.05) extent of sorting of short particle size. Intake of DM was higher in heifers fed 16AH and 19AH than in heifers fed 10BS (P < 0.001). Intake of NDF and physically effective NDF (peNDF) was greater in 13AH, 16AH, and 19AH than in 10BS (P < 0.01). The DMI of medium and short particle size was greater in 13AH, 16AH, and 19AH than in 10BS (P < 0.05), whereas DMI of long particle size was greater in 16AH and 19AH compared to 10BS (P < 0.001). Heifers fed 13AH, 16AH, and 19AH diets sorted against fine particle size and sorted for or tended to sort for short, medium, and long particle sizes. Meal length was greater in heifers fed 16AH and 19AH than 10BS (P < 0.05). Time spent eating was not affected by diet but time spent ruminating was greater in heifers fed 19AH than in 10BS (P < 0.05). Results indicate that the inclusion of alfalfa hay at 19% of incorporation caused an increase in DM, NDF, and peNDF intake, in comparison to the 10BS diet. In the same way, intake of long, medium, and short particle size was greater in this diet. Moreover, heifers fed 19AH sorted for medium particle size and tended to sort for long and short particles size, and against fine particle size. Sorting behavior and meal length increased in the 19AH diet, which leads us to think that sorting feed ingredients requires time and therefore lengthens the meal. Time spent ruminating was greater in heifers fed 19AH, thus reducing the risk of ruminal acidosis when animals are fed high concentrate diets.

Vertical grain size sorting in bedload transport on steep slopes with a coupled fluid-discrete element model

In order to study vertical grain size sorting in bedload sediment transport, numerical experiments of two-size particle mixtures were carried out, using a validated coupled fluid-discrete element model developed at Irstea. A 3D 10% steep domain, consisting at initial time of a given number of layers of 4 mm particles deposited on top of a coarser 6 mm particle bed, was sheared by a turbulent and supercritical fluid flow (Shields numbers of 0.1 and 0.3). The elevation of the centre of mass of the infiltrated fine particles is observed to follow the same logarithmic decrease with time, whatever the initial number of fine layers. This decrease is steeper for a higher Shields number. The main result is that this typical behaviour is related at first order to the particle shear rate depth profile.

Spatial Assessment of the Textural Characteristics and Sorting of Beach Deposits on the Barrier Lagoon Coastal Complex, Lagos Nigeria

The textural characteristics and sorting of the beach deposits on the Lagos barrier lagoon coastal complex was determined using grain size analysis of sediments. Fifty sediment samples were collected from five beaches namely Seme, Yovoyan, Lekki, Okun-Ajah and Orimedu. Inclusive mean and the inclusive standard deviation (sorting) were used to spatially assess the textural characteristics and sorting of sediment grain size so as to determine the prevailing wave energy level traversing the beaches and their significant variations at each beach using analysis of variance. The textural characteristics for the beaches showed dominantly coarse sands, moderately sorted sediments along the waterline, while medium sands, moderately well sorted sediments were found at the berm of the five beaches. The cross-shore profile of the beaches gave a dynamic system with moderately high wave energy between the waterline and the berm which affects the swash and backwash sediment grain size. Analysis of variance and post-hoc multiple comparisons according to Tukey-Kramer critical value was adopted to assess the spatial variations of the descriptive statistics and consequently, the wave energy level. The inclusive mean and the inclusive standard deviation were significantly different between the pairs of Seme and Okun-Ajah beaches in terms of textural characteristics and between the pairs of Seme and Yovoyan beaches in terms of sorting, accounting for the spatial variation in the descriptive statistics and thus the wave energy level between the beaches showing greater impacts with high wave energy level on Yovoyan and Okun-Ajah beaches than Seme beach due to their textural compositions. However, the hydrodynamic forces of the ocean were responsible for the moderately high wave energy level that traverses the beaches, making it unequivocal that the beaches on this barrier lagoon coastal complex are susceptible to coastal erosion.

Aeolian silt transport processes as fingerprinted by dynamic image analysis of the grain size and shape characteristics of Chinese loess and Red Clay deposits

This study applied dynamic image analysis (DIA; Sympatec Qicpic) to characterize the grain size and shape of Chinese aeolian sediments in order to fingerprint their transportation processes. This is the first time this technique has been applied to late Neogene and Quaternary silt particles (2–63μm) from the Chinese Loess Plateau (CLP). We selected four well-studied Quaternary loess-palaeosol sequences along a north-south transect across the CLP and compared their grain size distribution obtained by DIA with that yielded by laser diffraction particle size analysis (LD; Fritsch Analysette 22 and Sympatec HELOS KR). This comparison demonstrated that DIA is successfully able to differentiate loess units from palaeosols, and to characterize clearly spatiotemporal variations in the grain size records of loess-palaeosol sequences formed during the last two glacial and interglacial periods. This is consistent with grain size results obtained using LD. DIA is also able to characterize spatial variations in the more fine-grained aeolian Red Clay deposits underlying the Quaternary loess, and allows the quantification of the fluvial contribution to Red Clay sequences. DIA of the characteristics of grain shapes in loess-palaeosol sequences and Red Clay deposits revealed a systematic pattern, whereby the aspect ratio decreased with increasing grain size, indicating that systematic shape sorting occurred during the aeolian transportation of these dust particles. It could be inferred from our study that particles in a certain grain size range correspond to a specific aspect ratio range, and may in turn be aerodynamically distinguishable from each other and further correlated with the wind velocity/strength. Also evident from analysis of our DIA data was a subtle but systematic downwind decrease in the aspect ratio of the particles in the loess units. This observation suggests that elongated and/or flat particles (with a low aspect ratio) were transported further downwind than more symmetrically shaped particles (with a high aspect ratio). This study indicates that DIA of grain size and shape characteristics can be an additional powerful tool for identifying grain size and shape sorting trends, determining the dominant mode of transport, and reconstructing transport pathways of silt-sized aeolian sediments.

Improved performance of electroplated grinding wheels using a new method of controlled grain size sorting

The protrusion heights of grains on electroplated grinding wheel are uneven. This phenomenon has a negative influence on the grinding performance of electroplated grinding wheel. In this paper, CBN and diamond grains were sorted by hydraulic power method. Four kinds of electroplated grinding wheels were fabricated with selected and unselected CBN diamond grains. Then, the surface roughness of workpieces ground by the four kinds of grinding wheels were investigated and analyzed in contrast experiments. The experimental results show that the grains sorting method using hydraulic power can homogenize the size of grains; and lower ground surface roughness has been obtained by the electroplated grinding wheels with the help of the new method of controlled grain size sorting.

Elemental techniques for automated size sorting system considering problems and status of sorting process of ark shell (Scapharca subcrenata)

Elemental techniques for automated size sorting system considering problems and status of sorting process of ark shell (Scapharca subcrenata)

A recursive microfluidic platform to explore the emergence of chemical evolution.

We propose that a chemically agnostic approach to explore the origin of life, using an automated recursive platform based on droplet microfluidics, could be used to induce artificial chemical evolution by iterations of growth, speciation, selection, and propagation. To explore this, we set about designing an open source prototype of a fully automated evolution machine, comprising seven modules. These modules are a droplet generator, droplet transfer, passive and active size sorting, splitter, incubation chamber, reservoir, and injectors, all run together via a LabVIEWTM program integration system. Together we aim for the system to be used to drive cycles of droplet birth, selection, fusion, and propagation. As a proof of principle, in addition to the working individual modules, we present data showing the osmotic exchange of glycylglycine containing and pure aqueous droplets, showing that the fittest droplets exhibit higher osomolarity relative to their neighbours, and increase in size compared to their neighbours. This demonstrates the ability of our platform to explore some different physicochemical conditions, combining the efficiency and unbiased nature of automation with our ability to select droplets as functional units based on simple criteria.

Do natural biofilm impact nZVI mobility and interactions with porous media? A column study

Nanoparticles (NP) used as remediation agents for groundwater treatment may interact with biofilms naturally present, altering NP mobility and/or reactivity and thereby NP effectiveness. The influence of the presence of a multi species biofilm on the mobility of two types of zero-valent iron NP (nZVI; NANOFER 25S and optimized NANOFER STAR, NanoIron s.r.o. (Czech Republic)) was tested in laboratory experiments with columns mimicking aquifer conditions. Biofilms were grown in columns filled with sand in nitrate reducing conditions using groundwater from an industrial site as inoculum. After two months growth, they were composed of several bacterial species, dominated by Pseudomonas stutzeri. Biofilm strongly affected the physical characteristics of the sand, decreasing total porosity from ~30% to ~15%, and creating preferential pathways with high flow velocities. nZVI suspensions were injected into the columns at a seepage velocity of 10mday−1. Presence of biofilm did not impact the concentrations of Fe at the column outlet nor the amount of total Fe retained in the sand, as attested by the measurement of magnetic susceptibility. However, it had a significant impact on NP size sorting as well as on total Fe distribution along the column. This suggests nZVI-biofilm interactions that were confirmed by microscopic observations using SEM/STEM coupled with energy-dispersive X-ray spectroscopy. Our study shows that biofilm modifies the water flow velocity in the porous media, favoring the transport of large aggregates and decreased NP mobility due to physical and chemical interactions.

Particle-size sorting system of lunar regolith using electrostatic traveling wave

A particle-size sorting system of lunar regolith using an electrostatic traveling wave is developed for In-Situ Resource Utilization on the Moon to extract indispensable resources from the regolith and realize long-term exploration. The regolith is sorted by utilizing a balance between the electrostatic and gravitational forces, which are determined depending on particle size, in vacuum conditions where the particles are not subjected to air drag. In this study, the effect of particle charge on the particle motion is confirmed by conducting model experiments and numerical calculations based on the distinct element method. In addition, it was experimentally demonstrated that particles less than approximately 20 μm in diameter were efficiently separated from the bulk of a lunar regolith simulant FJS-1 in a vacuum condition (∼1.5 × 10−2 Pa), and the performance of the size sorting system on the Moon was predicted by the numerical calculations. The system utilizes only the electrostatic force, and it does not require any gas, liquid, or mechanical moving parts.

Bed load transport and incipient motion below a large gravel bed river bend

Abstract A new data set of bed load measurements in a cross-section at the exit of a river bend is presented. Data are analyzed to identify processes that contribute to the morphodynamic stability of gravel bed meanders. It is shown that boundary shear stress and bed material texture are strongly coupled, resulting in an almost equal mobility at incipient motion over the bend point bar in relation to channel flow stage. Conversely, for conditions above bankfull an excess of fine sediment towards the inner-bank, likely related to more intense crosswise flux and grain size sorting, results in size selective transport in relation to the local bed material. We suggest that bed armoring and structuring, as well as crosswise sediment flux, add stability to the outer-bank pool, while the point bar is eroded by large floods and restored by moderate flows. Results reveal the strong feedback of processes at different scales promoting stability at bends of gravel bed rivers.