Size Fractions Research Articles

Enzymatic production, physicochemical characterization, and prebiotic potential of pectin oligosaccharides from pisco grape pomace

The prebiotic capacity of Pectin Oligosaccharides (POS) is influenced by structural factors such as molecular size, composition, and degree of esterification, which affect their interaction with the gut microbiota. While existing literature has predominantly examined POS derived from apple and citrus pectins, the extrapolation of these findings to other pectin sources remains complex due to variations in their composition. This study focused on obtaining POS with prebiotic potential from pisco grape pomace through controlled enzymatic hydrolysis, resulting in three molecular size fractions: <3 kDa, 3–10 kDa, and > 10 kDa. The POS fractions were analyzed using FTIR, HPSEC, HPLC, and MALDI-TOF-MS techniques to characterize their physical-chemical properties. Each fraction presented distinct compositions, with the <3 kDa fraction showing a higher concentration of galacturonic acid and glucose, while the >10 kDa fraction was also composed of rhamnose and arabinose. Notably, the <3 kDa fraction supported greater biomass growth of the probiotic strain Lactobacillus casei ATCC 393 compared to the other fractions. In contrast, the non-probiotic strain Escherichia coli ATCC 25922 achieved the lowest biomass with this fraction. Consequently, the <3 kDa POS fraction exhibited the highest prebiotic index. This fraction, composed of oligomers from the rhamnogalacturonan region and arabino-oligosaccharides with a degree of polymerization between two and five, highlights its potential for further research and applications. Therefore, investigating other sources and optimizing extraction conditions could lead to developing novel prebiotic formulations that supply specific probiotic strains for a symbiotic product.

Implications for galaxy property estimation revealed by CO luminosity-FWHM relations in local star-forming galaxies

ABSTRACT This study explores a relationship between the $\rm {CO}$ luminosity-full width at half-maximum linewidth linear relation (i.e. the $\rm {CO}$ LFR) and mean galaxy property of the local star-forming galaxy sample in the xCOLDGASS data base, via a mathematical statement. The whole data base galaxies were separated into two subsamples based on their stellar masses and redshifts, being a help to examine the dependence issue of the $\rm {CO}$ LFR. Selecting the galaxy data with a stringent requirement was also implemented in order to assure the validly of the $\rm {CO}$ LFR. An algorithm of the linear regression was conducted with the data of the subsample. An assessment about the linear correlation manifested a valid $\rm {CO}$ LFR occurs in the selected galaxy of the subsample, and the intercept of the $\rm {CO}$ LFR may be related with the mean galaxy properties such as the molecular gas fraction and galaxy size. For the finding on the intercept of the $\rm {CO}$ LFR, we aligned that intercept with those galaxy properties via the involvement of a $\psi$ parameter. On evaluating the $\psi$ value with our local star-forming galaxy sample, we numerically determined a relationship between the statistical result and the galaxy property in a different stellar mass range. It also shows a possible method on estimating galaxy property.

A two-fluid multiphase flow model coupled with the population balance equations for the flow of a multidispersed particle system

SummaryWe present a two-fluid multiphase flow model that can be applied to the flow of polydisperse particle systems. In the model, the flow of polydisperse particle systems with different N particle sizes is considered only as two phases of fluid and particle phases, without considering the individual N phases, and the motion of particles with different diameters is represented by the motion characteristics of fluid and granular phases. The equations for the granular phase are obtained by averaging the Euler equations for the particles of different particle sizes. And the velocity of particles of different particle sizes is calculated by an explicit approximation, similar to determining the slip velocity in a mixed model of multiphase flow without solving the Eulerian momentum equation. Also, the conservation equation of particles of different particle sizes was obtained by adding the source term to the population balance equation, which is caused by the difference in the particle velocity of the particles with different particle sizes. The proposed method was compared with the results of experimental studies presented in the previous study to verify the validity of the method. The method has the advantage of not only visualizing the particle size fraction distribution but also of being stable in calculation and not increasing the computational effort significantly in studying the flow of polydisperse particle systems with particle size distribution.

Carbon Cycling in Marine Particles Based on Inorganic and Organic Stable Isotopes

The marine carbon cycle has a central role in biogeochemical cycling and a close interaction with the climate system. Here, we use the stable carbon isotope (δ13C) of particulate inorganic carbon (PIC) and particulate organic carbon (POC) in marine particles to diagnose carbonate dissolution and organic matter respiration processes in the ocean water column. We show PIC dissolution both in the euphotic zone, potentially driven by POC remineralization, and a preferential dissolution of coccoliths compared to foraminifera below the saturation horizon in the water column. Within the oxygen deficient zone (ODZ), POC remineralization and consequent respiration-driven PIC dissolution are both significantly diminished. We also demonstrate that POC remineralization preferentially removes a 13C-enriched component compared to isotopically-light bulk POC in both the large size fraction (LSF, > 51μ m) and small size fraction (SSF, 0.5 – 51μ m) of the pump particles, but exhibits a greater impact on the large particles because of its smaller inventory. Simultaneously, addition of a 13C-enriched heterotrophic or chemoautotrophic component to the SSF further increases the isotopic offset between SSF and LSF POC. Overall, this study uses δ13C to provide novel evidence for different biogeochemical processes in marine particles, and demonstrates carbonate dissolution in the ocean water column, both driven by bulk seawater chemistry and organic matter respiration within particles. The absence of O2 in the ODZ likely protects carbonate from dissolving by severely limiting organic matter respiration, thus reducing shallow PIC dissolution within the ODZs.

Effects of salinity and nutrient stress on a toxic freshwater cyanobacterial community and its associated microbiome: An experimental study.

We aimed to evaluate the ability of naturally occurring colonies of Microcystis, embedded in a thick mucilage, to persist in estuarine waters. In two batch experiments, we examined the dynamics of microbial communities, including cyanobacteria and associated heterotrophic bacteria, sampled from the field during both a cyanobacterial bloom (non-limiting nutrient condition) and the post-bloom period (limiting nutrient condition), and subjected them to a salinity gradient representative of the freshwater-marine continuum. We demonstrated that both Microcystis aeruginosa and M. wesenbergii survived high salinities due to osmolyte accumulation. Specifically, prolonged exposure to high salinity led to betaine accumulation in the cyanobacterial biomass. The relative abundance of the mcyB gene remained around 30%, suggesting no selection for toxic genotypes with salinity or nutrient changes. Microcystins were predominantly intracellular, except at high salinity levels (>15), where more than 50% of the total microcystin concentration was extracellular. In both nutrient conditions, over 70% of the heterotrophic bacterial community belonged to the Gammaproteobacteria family, followed by the Bacteroidota. Bacterial community composition differed in both size fractions, as well as along the salinity gradient over time. Finally, genus-specific core microbiomes were identified and conserved even under highly stressful conditions, suggesting interactions that support community stability and resilience.

Tailored biolixiviation of spent LiCoO2 cathode batteries for sustainable metal recovery: Effects of consortia adaptation and particle size

With the rise of lithium-ion battery production, recycling valuable metals like Fe, Al, Cu, Ni, and Co is crucial. This study explores sustainable recovery from spent LiCoO2 cathode batteries via biolixiviation, focusing on microbial adaptation and particle size. Batteries were shredded into four size fractions, with mid-sized fractions (0.5–6 mm) showing the highest metal content and optimal microbial conditions. Microbial consortia were isolated using Modified Czapek-Dox (MCD) and M9 media. Metagenomic analysis revealed shifts in dominant bacteria, with Acidobacteria and Actinobacteria initially, and Chloroflexi, Firmicutes, and Proteobacteria later. Enzymatic profiling showed increased activity of key enzymes under metal-adapted conditions. Biolixiviation experiments revealed the highest metal recovery in mid-sized fractions at different conditions including the influence of microbial adaptation and the type of media used: Fe (47.2 %-53.0 %), Al (38.7 %-40.5 %), Cu (29.0 %-31.0 %), Ni (25.6 %-27.4 % in the largest fraction), and Co (40.1 %-41.0 %). Adapted consortia had higher recovery rates, offering a sustainable recycling route.

Land Use affects the Soil Aggregation Pattern during Restoration of Degraded Land under Tropical Dry Climate

Soil aggregate formation and stability are crucial in safeguarding soil carbon pools, as they form the basic unit of soil structure in terrestrial ecosystems. The impact of different land uses on soil aggregation pattern has widely been studied but is limited under tropical dry climate conditions. This study aimed to determine the soil aggregation pattern at two soil depths (0-15 cm and 15-30cm) in three different plantations (Peltophorum pterocarpum, Eucalyptus globulus, and Acacia nilotica) established in degraded land under tropical dry climate. The soil aggregates were categorized into microaggregate, mesoaggregate and macroaggregate based on their size fractions which were determined by the wet sieving method. The percent of macroaggregate, mesoaggregate, and microaggregate fractions at 0-15 cm depth ranged from 62.2 – 82.6%, 31.6 – 36.7%, and 1.1 – 4.9 % respectively whereas at 15-30 cm depth, it ranged from 69.7 - 81.7%, 17.1 - 31.6%, and 1.2 - 2.8%. The mean weight diameter values at 0-15 cm and 15-30 cm soil depth ranged from 2.27-3.37mm and 2.85-3.35 mm respectively. The higher percentage of macroaggregate fractions in Peltophorum pterocarpum plantation compared to Eucalyptus globulus, and Acacia nilotica plantations indicated that the Peltophorum pterocarpum plantation has slightly more potential to improve aggregate formation and soil structure in the degraded lands under tropical dry climate. In addition, appropriate land use practices can increase soil aggregate stability in the study area.

Tire and road wear particles in infiltration pond sediments: Occurrence, spatial distribution, size fractionation and correlation with metals

Stormwater systems, such as infiltration ponds or basins, play a critical role in managing runoff water and reducing particulate pollution loads in downstream environments through decantation. Road runoff carries several pollutants, including trace metals and tire and road wear particles (TRWP). To improve our understanding of infiltration ponds as regards TRWP and their capacity to reduce TRWP loads, we have studied the occurrence, spatial distribution and size distribution of TRWP, as well as their relationship with metals, in considering the input of metals as tire additives, in the sediments of an infiltration pond located along the Nantes urban ring road (Western France), which happens to be a high-traffic roadway site. The sediment was analyzed using pyrolysis coupled with gas chromatography–mass spectrometry to determine the polymeric content of tires, specifically in quantifying the styrene-butadiene rubber (SBR) and butadiene rubber (BR) pyrolytic markers. By applying an SBR + BR-to-TRWP conversion factor, the results showed significant TRWP contamination, up to 65 mg/g, with a spatial enrichment from the entrance to the overflow section of the pond. Size fractionation revealed a bimodal distribution, indicating two distinct types of TRWP. The first type is characterized by small diameters (63–160 μm), suggesting the presence of TRWP less integrated with mineral and organic particles. The second type, characterized by larger diameters (200–500 μm), suggests a more pronounced integration with these same mineral and organic particles. A significant positive correlation between TRWP and metals (As, Cd, Cr, Cu, Li, Mo, Ni, Sb, V, Zn) was found (r > 0.739, p < 0.05). This correlation implies that TRWP and/or their associated phases may act as an indicator of metal contamination in the pond sediments. Lastly, a mass balance between TRWP inputs and the amount retained in the sediments underscores the role of infiltration ponds as “sinks” for TRWP.

A molecular dynamics study on mechanical performance and deformation mechanisms in nanotwinned NiCo-based alloys with nano-precipitates under high temperatures

Abstract Molecular dynamics simulations are performed to investigate the mechanical behavior of nanotwinned NiCo-based alloys containing coherent L12 nano-precipitates at different temperatures, as well as the interactions between the dislocations and nano-precipitates within the nanotwins. The simulation results demonstrate that both the yield stress and flow stress in the nanotwinned NiCo-based alloys with nano-precipitates decrease as the temperature rises, because the higher temperatures lead to the generation of more defects during yielding and lower dislocation density during plastic deformation. Moreover, the coherent L12 phase exhibits excellent thermal stability, which enables the hinderance of dislocation motion at elevated temperatures via the wrapping and cutting mechanisms of dislocations. The synergistic effect of nanotwins and nano-precipitates results in more significant strengthening behavior in the nanotwinned NiCo-based alloys under high temperatures. In addition, the high-temperature mechanical behavior of nanotwinned NiCo-based alloys with nano-precipitates is sensitive to the size and volume fraction of the microstructures. These findings could be helpful for the design of nanotwins and nano-precipitates to improve the high-temperature mechanical properties of NiCo-based alloys.

Substitution of Ce4+ for ionic at both A/B sites greatly improves the microwave responses of (Sr0.9Ca0.1)1/2La1/2Al1/2Ti1/2O3 perovskite ceramics

In this paper, (Sr0.9Ca0.1)1/2La1/2Al1/2Ti1/2O3-x wt.% CeO2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics were synthesized via solid state reaction. The effects of Ce4+ doping on microstructure and microwave dielectric properties were studied. All samples crystallized as perovskite single-phase. Ce4+ substitution for La3+ occurred at the A site for 0 < x ≤ 0.4, and for Ti4+ at the B site for 0.4 ≤ x ≤ 0.5. Oxygen vacancy concentration was linked to substitution sites, decreasing for x ≤ 0.3 and increasing for x ≥ 0.4, as shown by XPS analysis. The quality factor was influenced by oxygen vacancies, grain size, and packing fraction. Bonding valence and oxygen octahedral distortion affected the temperature coefficient of resonant frequency. At x = 0.4 and sintered at 1570 °C, the ceramics showed excellent properties: εr = 38.83, Q×f = 54058 GHz, τf = 2.137 ppm/°C, making it a promising low-loss dielectric ceramic for microwave communication applications.

Quantification of nanoscale precipitation in AA7050 using X-ray scattering, electron microscopy and automated particle counting techniques

Material strength is dependent on several factors, including precipitation strengthening, which is the main strengthening mechanism in AA7050 aluminum alloys. These alloys contain numerous nanometer-scale precipitates that occur throughout grains and along grain boundaries when subjected to a range of heat treatment conditions. In this study, three different characterization methods were used to characterize these nanoscale precipitates: conventional scanning transmission electron microscopy (STEM); laboratory-based small-angle X-ray scattering (SAXS); and a new software analysis tool developed by Thermo Fisher Scientific: automated particle workflow (APW). Each method was used to determine average precipitate size and volume fraction of precipitation in AA7050-T7451 specimens with variable post-T7 heat treatment procedures. STEM techniques measured the average particle size as ranging from 7.6 to 17.6 nm, compared to 6.3–10.7 nm for SAXS, and 7.4–10.8 nm for APW. Volume fraction determinations varied from 0.23 to 16 %, depending on method, and were the most difficult to quantify. Significant outcomes of the current study are that SAXS and APW are the most accurate methods for determining average particle size and that future work is needed to effectively analyze precipitate volume fraction.

A UV-resistant porous composite film for radiative cooling and enhanced hydrophobicity

Passive Daytime Radiative Cooling (PDRC) offers a promising strategy to reduce surface heat by reflecting solar radiation and emitting long-wave infrared radiation into space. However, the widespread application of PDRC is currently limited by challenges such as complex fabrication processes, high costs, and the materials’ susceptibility to outdoor aging. In this work, we fabricated a cost-effective, ultraviolet (UV)-resistant porous composite (UPC) film by phase separation technology. UPC films achieve high solar reflectance (0.92) and outstanding broadband longwave infrared thermal emissivity (0.975) by adjusting particle size and mass fractions of TiO2 particles embedded in Poly (methyl methacrylate) (PMMA). When applied to a drone, the films achieve a cooling effect of 12.6°C. Notably, the mid-infrared emissivity of UPC films remained stable after prolonged exposure to UV radiation (360 hours at an irradiance of 1 W/m2), with the reflectance decreasing by only 1.3 %. Software simulations were employed to evaluate the energy savings performance of UPC films in various urban environments, showing significant energy-saving benefits. Furthermore, after treatment with the modified solution, the surface contact angle of UPC films reaches 152.5°, providing excellent resistance to contamination. This work contributes to the advancement of low-cost, durable, and energy-efficient cooling solutions.

Effect of different heat inputs on the microstructure and mechanical properties of the laser welded joint of CLF-1 steel

Abstract In this study, we examined the effects of various heat inputs on the microstructure and mechanical properties of the laser-welded joints of CLF-1 low-activation ferritic/martensitic steel medium-thick plates, which are used in the Test Blanket Module (TBM). The results indicate that under four different welding heat inputs (2727 J/cm, 3000 J/cm, 3563 J/cm, and 4500 J/cm), the weld microstructure is primarily composed of a large amount of lath martensite and a small amount of δ-Fe. As the heat input increases, the average width of lath martensite in the weld microstructure progressively increases, while the average volume fraction and width size of δ-Fe experience a significant increase. When the heat input surpasses 3563 J/cm, δ-Fe exhibits a dense aggregation. The tensile properties of the joints created under different heat inputs are superior to those of the base material. At the lowest heat input, the maximum impact toughness of the weld reaches 40 J.

Effects of solution treatment on microstructure and properties of Ti-5.7Al-3.9Sn-0.91Mo-3.4Zr-0.40Si-0.38Nb-0.95Ta titanium alloy

This study investigated the effects of solution treatments under various conditions on the matrix and silicides microstructure and their impact on the mechanical properties of high-temperature Ti60 (Ti-5.7Al-3.9Sn-0.91Mo-3.4Zr-0.40Si-0.38Nb-0.95Ta) titanium alloy. The microstructure evolution during solution treatments was characterized, and the tensile properties at 600 °C and room temperature (RT) were investigated. The results show that the fraction and grain size of martensite and silicides can be tailored through solution treatments. With increasing solution temperature, the fraction of primary α (αp) phase and silicides decreases, while that of the transformed β (βt) microstructure increases. After solution treatment at 1025 °C, the yield strength (YS) and ultimate tensile strength (UTS) reach 685.0 MPa and 900.8 MPa, respectively, at 600 °C, increasing by 18.0% and 27.0%, respectively, compared to the initial state. The elongation (EL) remains at 16.2%. The strengthening mechanisms of Ti60 alloy include grain boundary strengthening of the αp phase and martensite formed during rapid cooling, as well as precipitation strengthening of the silicides. With increasing solution temperature from 950 °C to 1025 °C, the fraction of martensite strengthening increases from 38.4% to 89.3%, while the fraction of precipitation strengthening of silicides decreases from 3.63% to 1.17%.

Left ventricular size and heart failure: A cardiac MRI assessment of 38,129 individuals from the UK Biobank

BackgroundPrevious studies suggest that prevalent heart failure (HF) differs based on left ventricular ejection fraction (LVEF) and left ventricular (LV) chamber size. Furthermore, the prevalence of HF with preserved ejection fraction (HFpEF) is often considered approaching, or exceeding that of HF with reduced ejection fraction in the community. AimThe aim of this study was to evaluate prevalent and incident HF based on LVEF and CMR-determined LV size within a large community-dwelling cohort. MethodsIndividuals from the United Kingdom Biobank (UKB) who underwent CMR and had available health record linkage to allow ascertainment of HF diagnosis were included. The cohort was analysed according to LVEF, LV end-diastolic volume (LVEDV) quartiles and LVEDV indexed to body surface area (LVEDVi). Results38,129 individuals were included, comprising those with reduced LVEF (LVEF<50 %, n = 5096) and preserved LVEF (LVEF 50–60 %, n = 22,907, LVEF≥60 %, n = 10,126). Prevalent HF was highest in males with LVEF<50 %, and participants with reduced LVEF had higher rates of incident HF (p < 0.001) during the follow-up period (median = 2.46 years from CMR). Mean LVEDV and LVEDVi were largest in individuals with EF < 50 % (146.9 ± 36.2 ml and 76.8 ± 16.4 ml/m2 respectively). Compared to the smallest quartiles, the largest quartiles for LVEDV were associated with increased odds of HF (odds ratio 2.14 [95 % confidence interval 1.47–3.12], p < 0.001). ConclusionsOver 50 % of HF cases occur in individuals with LVEF ≥50 %, however HF prevalence is highest in those with reduced LVEF, particularly in males. Larger LV size is associated with increased HF across the LVEF spectrum.

Influence of climate on soil viral communities in Australia on a regional scale

AbstractViruses play a crucial role in regulating microbial communities and ecosystem functioning. However, the biogeographic patterns of viruses and their responses to climate factors remain underexplored. In this study, we performed viral size fraction metagenomes on 108 samples collected along a 2600 km transect across Australia, encompassing distinct climate conditions. A total of 14,531 viral operational taxonomic units were identified. Climate factors had a greater influence than edaphic and biotic factors on driving the alpha diversity of viral communities. The strongest relationship was observed between mean annual temperature and the diversity of viral communities. Moreover, climate factors, particularly aridity index, were the primary drivers of viral community structure. Overall, these findings underscore the pivotal role of climate factors in shaping viral communities and have implications for understanding how climate change influences soil viral ecology.

Synergistic impact mechanism of particle size and morphology in superalloy powders for additive manufacturing

The particle size and morphology of superalloy powders are crucial parameters that significantly influence the performance of additive manufacturing (AM) processes. This study investigates the effects of atomization pressure on these characteristics through a combination of computational fluid dynamics (CFD) simulations and vacuum induction melting gas atomization (VIGA) experiments. The CFD simulations revealed that increasing the atomization pressure from 2.0 MPa to 3.5 MPa resulted in a rise in maximum gas velocity from 526 m/s to 537 m/s and a reduction in median particle size (D50) from 60.9 μm to 37.5 μm. Subsequent experiments demonstrated a decrease in D50 from 52.9 μm to 35.6 μm, and sphericity from 0.9432 to 0.9377, as pressure increased. The particle size results of the atomization experiments and numerical simulations show strong consistency, validating the accuracy of the numerical simulation results. The volume of hollow particles also increased slightly in specific size fractions. These results suggest that higher atomization pressures produce finer powders with lower sphericity, but also promote particle adhesion, reducing the overall refinement effect. This study provides insights into optimizing atomization conditions for the precise control of superalloy powders in AM.

Distribution of soil fertility indices in aggregate size fractions under different land-use types for coarse-textured soils of the derived savannah

The research investigated the distribution of soil fertility indices among aggregate-size fractions across three land-use types (forested, cultivated, and fallow lands) for loamy sand at Ede-Oballa, a derived savannah in southeastern Nigeria. Surface soil samples from these land-use types were air-dried and separated into &lt;0.25 mm, 0.25-0.5 mm, 0.5-1.0 mm, 1.0-2.0 mm, 2.0-4.0 mm, and 4.0-8.0 mm aggregates before analyses. There were significant interaction effects of land-use type and aggregate-size fraction on the distribution of soil particle sizes (sand, silt, and clay) and contents of total nitrogen, available phosphorus, exchangeable bases (Mg2+ and Na+), and exchangeable acidity as well as apparent cation exchange capacity (CEC). Land-use type affected soil pH, K+, Ca+, and percent base saturation but not soil organic carbon (SOC), which was rather unevenly distributed among the aggregate-size fractions. The distribution of most fertility indices, those defining CEC, and SOC content favoured &gt;2.0 mm (large), 0.25-0.5 mm and &lt;0.25 mm (micro-) aggregates, respectively, under cultivated land. However, soil total nitrogen and exchangeable acidity contents were best improved in the largest (4.0-8.0 mm) aggregates under forested and fallow lands, respectively. The study highlights the potential of land-use types generally and arable-crop cultivation specifically to engender aggregates of different sizes with specific roles in improving soil quality and fertility.

Anatomy of Niger and Benue river sediments from clay to granule: grain-size dependence and provenance budgets, Nigeria

ABSTRACT This study explores in detail the complexity of textural–compositional relationships in fluvial sediments. To this aim, fifteen size fractions (from clay to granule) of three sediment samples characterized by virtually identical size distribution from the Niger and Benue rivers in central Nigeria were separately analyzed by multiple methods (optical microscopy, manual and semi-automated Raman spectroscopy, X-ray diffraction, elemental geochemistry, Nd isotopes). The independent mineralogical and geochemical datasets thus obtained allowed us to investigate processes of sediment generation for five diverse size modes (clay, fine cohesive silt, very coarse frictional silt, very fine sand, coarse sand) derived in different proportions from different sources (wind-blown dust, soils and paleosols, fine-grained and coarse-grained siliciclastic units, igneous and metamorphic bedrocks). Controls on the size distribution of detrital minerals (settling equivalence, size inheritance, weathering, mechanical durability, and chemical durability through multiple sedimentary cycles) were examined, specifically focusing on tectosilicates and on the long-standing petrological problem of feldspar–grain-size relations. Various factors determine the composition of different size modes: kaolinite-dominated clay derives from both deeply weathered soils or paleosols and distant Saharan sources; cohesive silt is largely recycled from mudrocks and soils formed in sedimentary basins. The proportion of detritus derived first-cycle from basement rocks increases from very coarse silt to very fine sand, whereas the coarse-sand mode is quartz-dominated with scarce plagioclase and amphibole and local occurrence of garnet, staurolite, monazite, or xenotime reflecting a combined influence of size inheritance from igneous (pegmatite) and metamorphic sources, mechanical and chemical durability, and recycling from coarse-grained siliciclastic units. Sediment budgets based on mineralogical, geochemical, and geochronological signatures consistently indicate dominance of Benue sediment supply, although the contribution from the Niger mainstem to the Niger Delta is inferred to have been notably greater in the wetter past, before clastic fluxes dropped in response to the aridification of the Sahel.

Dynamic data-driven multiscale modeling for predicting the degradation of a 316L stainless steel nuclear cladding material

We have developed a long short-term memory stacked ensemble (LSTM-SE) surrogate modeling approach that can provide rapid predictions of microstructural evolution and the resultant mechanical properties of American Iron and Steel Institute (AISI) 316L series stainless steel (SS316L) fuel cladding under conditions of varying temperature and radiation dose rate. To acquire training data, we developed and implemented a kinetic Monte Carlo (KMC) model to simulate precipitation kinetics of M23C6, γ’, and G phases within SS316L cladding. Experimentally reported precipitation kinetics of SS316L in literature were linked to the kinetic parameters of the simulated precipitation in our KMC model. The model was then used to simulate microstructure evolution under synthetically generated treatments of varying temperature and radiation dose rate for periods of up to 3000 h. Changes in volume fraction, number density, and particle size of precipitates were recorded, and particle area fractions were correlated using statistical methods to develop the surrogate model. Simultaneously, the mechanical properties of the simulated microstructures were evaluated using microstructure-based finite element method (FEM) analysis to determine the elastic modulus, yield stress, ultimate tensile strength, and elongation to failure of the aged microstructures. Using this approach, our surrogate model can predict precipitation behavior within 0.25 % volume fraction and mechanical properties within 6 % relative error from the values predicted by the KMC and FEM models using 50 training simulations as input. The trained recurrent neural network-based model can return estimations of precipitation kinetics and mechanical properties ∼1000 times faster than the physics-based codes. This work demonstrates, as a proof of concept, that microstructural evolution under variable conditions can be predicted using a statistics-based model informed by a practicably obtainable dataset. The potential applications of this type of modeling framework are discussed.