Substrate Conditions Research Articles

Optimizing feedstock organic composition to regulate humification and heavy metal passivation during solid-state anaerobic digestion

This study uncovered the impacts of feedstock organic composition, comprising proteins, lignocellulose, and lipids, on humification and passivation of heavy metals (HMs) in solid-state anaerobic digestion (SSAD). Mantel tests and partial least squares structural equation modeling (PLS-SEM) results revealed that copper (Cu) and zinc (Zn) passivation predominantly occurred through complexation with humic acid (HA). In contrast, lead (Pb) and chromium (Cr) passivation were pH-dependent as influenced by substrate conditions in SSAD. Increasing protein content in the feedstock facilitated lignocellulose biodegradation to enhance HA formation, and thus augmenting Cu and Zn passivation. Furthermore, the improved biodegradation of organic components elevated the substrate pH, further enhancing Pb and Cr passivation. Such improvement was notable when the protein: lignocellulose: lipid ratio of feedstock was regulated to 4.1:3.7:2.2, which increased HA contents to 35.25% and pH to 9 to enhance the passivation of Cu, Pb, and Cr by 0.48%, 52.0%, and 17.9%, respectively.

Impact of substrate particle size on the digging behavior of the juveniles of the smooth fan lobster Ibacus novemdentatus Gibbes, 1850 (Decapoda: Pleocymeta: Scyllaridae)

Abstract Aquaculture techniques for fan lobsters are still in an early stage of development due to the limited knowledge on their early-benthic stages. As the lobsters are diggers and thus the substrate influences their survival and growth, the physical characteristics of such substrates are a crucial environmental factor in an aquaculture setting. The appropriate size ranges of the substrate particles are nevertheless unknown. We studied the digging behavior of the juvenile of the smooth fan lobster, Ibacus novemdentatusGibbes, 1850, and examined its ability to dig into sand of different particle sizes to determine the optimal substrate conditions. Digging was completed by 100% of the juveniles in fine sand, 85.7% in medium-size sand, 25.7% in medium-coarse sand, and none in coarse sand. Juvenile digging involves three stages: searching for a location to dig, inserting the tail fan, and submerging into the sediment. The median length of time from the beginning of the experiment to the commencement of tail insertion in juveniles that completed digging did not differ significantly (P = 0.97) with the particle size. Juveniles placed on the substrate with medium-size and medium-coarse sand took significantly longer (P < 0.01) from the start of tail insertion to the complete submersion than those on fine sand. Considering the success rates of digging and the time required to complete digging, fine sand was the most appropriate substrate among the tested particle-size ranges. The juveniles that failed to complete the digging repeated a digging position and attempted to insert their tail fan into the sand without submerging. These juveniles took a significantly longer time (P < 0.05) to attempt to insert their tail fan than the juveniles that successfully completed digging, suggesting that juveniles placed on inappropriate substrates may spend more energy on digging and become more stressed.

Uncovering the oxic-suboxic microenvironment change in seamount flank through authigenic clay minerals in basaltic substrate of ferromanganese crust, Magellan seamount

In low-temperature ocean environments, basalt alteration by seawater precipitates authigenic clay minerals that serve as proxies for reconstructing paleo-ocean conditions because they reflect surrounding oxic-suboxic conditions. In this study, alteration rims on basaltic substrate associated with ferromanganese (Fe-Mn) crust from the Magellan seamount KC-7 were identified by microscopic analyses. Mineralogical and geochemical analyses indicate that the alteration rims contain K-enriched Fe-smectite and glauconite which suggest that seawater-basalt interaction occurred under oxic conditions and in the presence of organic-rich suboxic conditions, respectively. These disparate environmental conditions suggest that the environment changed before and after Fe-Mn crusts formed. During the Cenozoic hyperthermal events, oxygen-rich bottom water was supplied by upwelling driven by the geomorphological influence of the seamounts, which may have led to basalt alteration. The K-enriched Fe-smectites, which indicate oxic condition, formed via seawater-basalt interactions before the Fe-Mn crust incrustation. Later, during the Eocene, the opening of the Drake Passage enhanced the supply of oxygen-rich seawater to the Magellan Seamounts, thereby enabling the formation of hydrogenetic Fe-Mn crust. After the incrustation of seamount flanks with Fe-Mn crusts, the carbonate fluorapatite (CFA), a product of the global phosphatization event, filled the pores in the Fe-Mn crusts during Oi-1 glaciation. As a result, seawater-basalt interactions decreased and led to suboxic conditions, in which glauconite formed as organic matter was remineralized under the organic-rich conditions in the basaltic substrate. This authigenic clay mineral formation sequence suggests that changes in ocean circulation and subsequent changes in the oxic-suboxic conditions in the basaltic substrate occurred on the western Pacific seamount KC-7.

Enhanced Rock Weathering as a Source of Metals to Promote Methanogenesis and Counteract CO2 Sequestration.

Enhanced weathering of (ultra)mafic rocks has been proposed as a promising approach to sequester atmospheric CO2 and mitigate climate change. However, these silicate rocks contain varying amounts of trace metals, which are essential cofactors of metallaenzymes in methanogens. We found that weathering of crushed peridotite and basalt significantly promoted the growth and methanogenesis of a model methanogen─Methanosarcina acetivorans C2A under the condition of excess substrate. The released trace metals from peridotite and basalt, especially Fe, Ni, and Co, accounted for the promotion effect. Observation at different spatial scales showed a close association between the rocks and cells. Proteomic analysis revealed that rock amendment significantly enhanced the expression of core metalloenzymes in the methylotrophic methanogenesis pathway. Our study uncovers a previously unrecognized but important negative effect of enhanced rock weathering on methane production, which may counteract the carbon sequestration effort.

Prospect for Fine and Coarse Coal Waste Deployment for a Constructed Technosol and Eragrostis Tef Growth

The aim of this study was to evaluate soil properties and Eragrostis tef (teff) growth on Technosols produced from coarse and fine coal wastes from Moatize Mine, Mozambique. The experiment was performed in triplicate in 30 L containers filled with different substrate conditions, composed of fine coal waste, coarse coal waste, agricultural soil, and sewage sludge as an organic matter source. The soil analyses included bulk density, available water capacity, permeability, and fertility. Plant growth was monitored for biomass production and plant tissue composition. All the substrates presented a good available water capacity and a proper drainage condition. Regarding soil fertility, there were shortages of potassium and boron in the substrates composed exclusively of coal wastes, which was reflected in the composition of the plant tissue. Even so, plant growth was statistically equivalent to the control in all conditions, except for the substrate produced exclusively with fine coal waste and sewage sludge, which presented a better performance. Technosols are an alternative for reducing the final mine waste volume, and Eragrostis tef is used as a means for land use after the mining process, with social gains, and as a tool in an ecological process for restoring coal mining sites.

The divergent role of straw return in soil O2 dynamics elucidates its confounding effect on soil N2O emission

The divergent effects of straw returns on nitrous oxide (N2O) emissions from soil require elucidation of the underlying mechanisms and factors that explain the inconsistency in in-situ conditions. We conducted a field experiment based on a long-term trial under different regimes of nitrogen (N) fertilization and straw management, complemented by laboratory incubation experiments involving visualized O2 dynamics imaging. In the field trial, we performed hourly basis high-time-resolution measurements of soil matrix oxygen (O2), N2O concentrations and fluxes during N2O “hot moment” events. We found that straw return increased cumulative N2O emissions by 32.7% under conventional high N input (Ncon), but showed no effect on N2O emission under optimized N input (Nopt). In situ O2 content and further microcosm experiments with visualized O2 spatiotemporal distribution suggested that long-term straw return increases porosity and soil O2 content, which reduced N2O emission under low N substrate conditions by improving soil pore structure and aeration during “hot moment” events. By contrast, straw return increased N2O emission via creating short-term O2 depletion zone and triggering denitrification in anoxic microsites when excess N substrate was available. Although straw return showed inconsistent effects on N2O emission under different N application rates, it consistently decreased N2O concentration in the soil matrix during the "hot moment" events, suggesting that straw return increases the transport of the produced N2O in soil matrix to the soil surface. Our study underscores the multifaceted role of straw return in soil O2 dynamics, i.e., stimulating O2 consumption in a short-term microscale of soil, but increasing soil porosity in a long-term mesoscale of soil. This explains the confounding effects of straw management on the production and transportation of soil N2O in situ and emphasizes the importance of optimized N fertilization for reducing the “hot moment” N2O emissions when straw is incorporated.

Sulfone as traceless activating group: Divergent synthesis of α-fluoroamides with C–F quaternary stereocenters

A novel approach to α-fluoroamides bearing a C–F quaternary stereocenter is reported herein. With sulfone installed as the activating group, an alkyl group as well as a fluorine atom was introduced successively under mild conditions. Subsequently, heterolytic fission of the C–S bond occurred smoothly under photoredox conditions to afford a tertiary radical, which then engaged in varied intramolecular cyclizations depending on substrate structure and condition applied, rendering sulfone an overall traceless activating group.

Analyses and control of interphase structures and adhesion properties of epoxy resin/epoxy resin for development of CFRP adhesion systems

In the adhesion of carbon fiber reinforced plastics (CFRP), the boundary regions were composed of only epoxy resins of CFRP matrix and adhesives, and their similar epoxy structures pose significant difficulty in studying the adhesion mechanism. Herein, we focused on structure and properties of laminates of epoxy resin substrates and adhesives with different curing conditions of substrates. We prepared laminates using deuterated epoxy adhesives or fluorinated epoxy adhesives, and their boundary regions were identified through confocal Raman scattering measurements. The regions were distributed into “penetration” and “interphase”. In particular, the penetration phase is a key of the adhesion properties. The penetration behaviors strongly depended on the crosslinking densities of the adherends, suggesting that the penetration regions would be directly impacted by the curing conditions of the substrates and molecular size of epoxy adhesive precursors. Our findings provide insights into novel designs of the reliable adhesion-based manufacturing systems of CFRP.

Promoting subsurface Sn incorporation at Nb(100) oxide surface sites leading to homogeneous Nb3Sn film growth for superconducting radiofrequency applications

For next-generation superconducting radiofrequency (SRF) cavities, the interior walls of existing Nb SRF cavities are coated with a thin Nb3Sn film to improve the superconducting properties for more efficient, powerful accelerators. The superconducting properties of these Nb3Sn coatings are limited due to inhomogeneous growth resulting from poor nucleation during the Sn vapor diffusion procedure. To develop a predictive growth model for Nb3Sn grown via Sn vapor diffusion, we aim to understand the interplay between the underlying Nb oxide morphology, Sn coverage, and Nb substrate heating conditions on Sn wettability, intermediate surface phases, and eventual Nb3Sn nucleation. In this work, Nb-Sn intermetallic species are grown on a single crystal Nb(100) in an ultrahigh vacuum chamber equipped with in situ surface characterization techniques including scanning tunneling microscopy, Auger electron spectroscopy, and x-ray photoelectron spectroscopy. Sn adsorbate behavior on oxidized Nb was examined by depositing Sn with submonolayer precision on a Nb substrate held at varying deposition temperatures (Tdep). Experimental data of annealed intermetallic adlayers provide evidence of how Nb substrate oxidization and Tdep impact Nb-Sn intermetallic coordination. The presented experimental data contextualize how vapor and substrate conditions, such as the Sn flux and Nb surface oxidation, drive homogeneous Nb3Sn film growth during the Sn vapor diffusion procedure on Nb SRF cavity surfaces. This work, as well as concurrent growth studies of Nb3Sn formation that focus on the initial Sn nucleation events on Nb surfaces, will contribute to the future experimental realization of optimal, homogeneous Nb3Sn SRF films.

Substrate stiffness modulates extracellular vesicles’ release in a triple-negative breast cancer model

Aim: The microenvironment effect on the tumoral-derived Extracellular Vesicle release, which is of significant interest for biomedical applications, still represents a rather unexplored field. The aim of the present work is to investigate the interrelation between extracellular matrix (ECM) stiffness and the release of small EVs from cancer cells. Here, we focus on the interrelation between the ECM and small extracellular vesicles (sEVs), specifically investigating the unexplored aspect of the influence of ECM stiffness on the release of sEVs. Methods: We used a well-studied metastatic Triple-Negative Breast Cancer (TNBC) cell line, MDA-MB-231, as a model to study the release of sEVs by cells cultured on substrates of different stiffness. We have grown MDA-MB-231 cells on two collagen-coated polydimethylsiloxane (PDMS) substrates at different stiffness (0.2 and 3.6 MPa), comparing them with a hard glass substrate as control, and then we isolated the respective sEVs by differential ultracentrifugation. After checking the cell growth conditions [vitality, morphology by immunofluorescence microscopy, stiffness by atomic force microscopy (AFM)], we took advantage of a multi-parametric approach based on complementary techniques (AFM, Nanoparticle Tracking Analysis, and asymmetric flow field flow fractionation with a multi-angle light scattering detector) to characterize the TNBC-derived sEV obtained in the different substrate conditions. Results: We observe that soft substrates induce TNBC cell softening and rounding. This effect promotes the release of a high number of larger sEVs. Conclusion: Here, we show the role of ECM physical properties in the regulation of sEV release in a TNBC model. While the molecular mechanisms regulating this effect need further investigation, our report represents a step toward an improved understanding of ECM-cell-sEVs crosstalk.

Effects of different straw breeding substrates on the growth of tomato seedlings and transcriptome analysis.

Traditional substrate cultivation is now a routine practice in vegetable facility breeding. However, finding renewable substrates that can replace traditional substrates is urgent in today's production. In this study, we used the 'Pindstrup' substrate as control and two types of composite substrates made from fermented corn straw (i.e. 0-3 and 3-5mm) to identify appropriate substrate conditions for tomato seedling growth under winter greenhouse conditions. Seedling growth potential related data and substrate water content related data were tested to carry out data-oriented support. Since the single physiological data cannot well explain the mechanism of tomato seedlings under winter greenhouse condition, transcriptomic analysis of tomato root and leaf tissues were conducted to provide theoretical basis. The physiological data of tomato seedlings and substrate showed that compared with 0-3mm and Pindstrup substrate, tomato seedlings planted in 3-5mm had stronger growth potential and stronger water retention, and were more suitable for planting tomato seedlings. Transcriptome analysis revealed a greater number of DEGs between the Pindstrup and the 3-5mm. The genes in this group contribute to tomato growth as well as tomato stress response mechanisms, such as ABA-related genes, hormone-related genes and some TFs. The simulation network mechanism diagram adds evidence to the above conclusions. Overall, these results demonstrate the potential benefits of using the fermented corn straw of 3-5mm for growing tomato seedlings and present a novel method of utilizing corn straw.

Architecture of CTPS filament networks revealed by cryo-electron tomography

The cytoophidium is a novel type of membraneless organelle, first observed in the ovaries of Drosophila using fluorescence microscopy. In vitro, purified Drosophila melanogaster CTPS (dmCTPS) can form metabolic filaments under the presence of either substrates or products, and their structures that have been analyzed using cryo-electron microscopy (cryo-EM). These dmCTPS filaments are considered the fundamental units of cytoophidia. However, due to the resolution gap between light and electron microscopy, the precise assembly pattern of cytoophidia remains unclear. In this study, we find that dmCTPS filaments can spontaneously assemble in vitro, forming network structures that reach micron-scale dimensions. Using cryo-electron tomography (cryo-ET), we reconstruct the network structures formed by dmCTPS filaments under substrate or product binding conditions and elucidate their assembly process. The dmCTPS filaments initially form structural bundles, which then further assemble into larger networks. By identifying, tracking, and statistically analyzing the filaments, we observed distinct characteristics of the structural bundles formed under different conditions. This study provides the first systematic analysis of dmCTPS filament networks, offering new insights into the relationship between cytoophidia and metabolic filaments.

Repeated glucose oscillations in high cell-density cultures influence stress-related functions of Escherichia coli.

Engineering microbial cells for the commercial production of biomolecules and biochemicals requires understanding how cells respond to dynamically changing substrate (feast-famine) conditions in industrial-scale bioreactors. Scale-down methods that oscillate substrate are commonly applied to predict the industrial-scale behavior of microbes. We followed a compartment modeling approach to design a scale-down method based on the simulation of an industrial-scale bioreactor. This study uses high cell-density scale-down experiments to investigate Escherichia coli knockout strains of five major glucose-sensitive transcription factors (Cra, Crp, FliA, PrpR, and RpoS) to study their regulatory role during glucose oscillations. RNA-sequencing analysis revealed that the glucose oscillations caused the down-regulation of several stress-related functions in E. coli. An in-depth analysis of strain physiology and transcriptome revealed a distinct phenotype of the strains tested under glucose oscillations. Specifically, the knockout strains of Cra, Crp, and RpoS resulted in a more sensitive transcriptional response than the control strain, while the knockouts of FliA and PrpR responded less severely. These findings imply that the regulation orchestrated by Cra, Crp, and RpoS may be essential for robust E. coli production strains. In contrast, the regulation by FliA and PrpR may be undesirable for temporal oscillations in glucose availability.

Thermal regime of High Arctic tundra ponds, Nanuit Itillinga (Polar Bear Pass), Nunavut, Canada

Abstract. This study evaluates the seasonal and inter-seasonal temperature regime of small tundra ponds ubiquitous to an extensive, low-gradient wetland in the Canadian High Arctic. Pond temperatures can modify evaporation and ground thaw rates, impact losses of greenhouse gases, and control the timing and emergence of insects and larvae critical for migratory-bird feeding habits. We focus our study on thaw ponds with a range of hydrologic linkages and sizes across Nanuit Itillinga, formerly known as Polar Bear Pass (PBP), Bathurst Island, and compare their thermal signals to other Arctic ponds. Pond temperatures and water levels were evaluated using temperature and water level loggers and verified by regular manual measurements. Other environmental data collected included microclimate, frost table depths, and water conductivity. Our results show that there is much variability in pond thermal regimes over seasons, years, and space. Cumulative relative pond temperatures were similar across years, with ponds normally reaching 10–15 °C for short to longer periods, except in 2013, which experienced a cold summer season during which pond temperatures never exceeded 5 °C. Pond frost tables and water conductivities respond to variable substrate conditions and pond thermal patterns. This study contributes to the ongoing discussion on climate warming and its impact on Arctic landscapes.

Metabolic substrate conditions direct activity of nicotinamide nucleotide transhydrogenase (NNT), thereby modifying mitochondrial pyruvate metabolism

Metabolic substrate conditions direct activity of nicotinamide nucleotide transhydrogenase (NNT), thereby modifying mitochondrial pyruvate metabolism

Effects of Substrate and Annealing Conditions on the Ferroelectric Properties of Non-Doped HfO2 Deposited by RF Plasma Sputter.

In this study, the effect of annealing and substrate conditions on the ferroelectricity of undoped hafnium oxide (HfO2) was analyzed. Hafnium oxide was deposited on various substrates such as platinum, titanium nitride, and silicon (Pt, TiN, Si) through RF magnetron sputtering. Annealing was performed in a nitrogen atmosphere at temperatures ranging from 400 to 600 °C, and the process lasted anywhere from 1 to 30 min. As a result, it was confirmed that the orthorhombic phase, the main cause of ferroelectricity, was dominant after a post-anneal at 600 °C for 30 min. Additionally, it was observed that interface mixing between hafnium oxide and the substrate may degrade ferroelectricity. Accordingly, the highest remanent polarization, measured at 14.24 μC/cm2, was observed with the Pt electrode. This finding was further corroborated by piezo force microscopy and endurance tests, with the results being significant compared to previously reported values. This analysis demonstrates that optimizing substrate and annealing conditions, rather than doping, can enhance the ferroelectricity of hafnium oxide, laying the foundation for the future development of ferroelectric-based transistors.

Bond performance of fly ash-based geopolymer mortar in simulated concrete sewer substrate

Geopolymers have been extensively explored as a promising repair material for deteriorated Ordinary Portland Cement (OPC) concrete elements. However, knowledge of the adhesion performance of geopolymer to concrete substrates is limited. This study investigates the bond performance of low calcium fly ash geopolymer (FAGP) mortar and concrete for holistic acidic environmental conditions, such as in sewer rehabilitation. The bond evaluation was conducted by slant-shear test, performed at different substrate conditions, namely Rough-Dry, Rough-Saturated, Smooth-Dry and Smooth-Saturated, to simulate the in-service condition of a typical sewer pipe wall. The standard OPC repair mortar and a commercially available proprietary geopolymer repair product (P-GP) were evaluated and compared as controls to ascertain the viability of geopolymer for repair application. The shear bond strength of FAGP mortar was found to be in the order of 14 MPa, outperforming OPC and P-GP in all substrate conditions. Even though FAGP bond strength was insensitive to roughened substrate moisture levels, the synergistic effect of smoothness and moisture condition appeared detrimental. The testing of the prototype geopolymer-coated concrete pipe under line loading showed no sign of delamination at the bond plane. OPC and P-GP exhibited a distinct bond separation, which commenced at only 20 % of the ultimate load. The acid resistance and low permeability of FAGP mortar appeared to aid in preserving the repair bond.

Comparative analysis of seagrass habitat structure: distinct patterns at semi-enclosed and open sites in South Sulawesi, Indonesia

Habitat structure in the seagrass ecosystems are crucial for coastal biodiversity and substrate stability. The purpose of this research conducted from June to December 2021 in South Sulawesi Province, Indonesia was to examine the habitat structure of seagrass beds at two sites with different levels of exposure: Puntondo (semi-enclosed bay) and Batu Kalasi (exposed). Species identification, non-metric multidimensional scaling (nMDS), Bray Curtis cluster analysis, similarity percentage (SIMPER), Particle Size Analysis (PSA), and satellite imagery were used to evaluate complexity, heterogeneity, sediment particle size, and extent. The presence of macroalgae and coral species at Batu Kalasi, likely related to substrate condition, contributed to significant differences in seagrass community composition. The nMDS and Bray Curtis cluster analyses revealed patterns of complexity, while satellite imagery revealed habitat heterogeneity. Seagrass meadow tracking showed a larger and more patchy area in Puntondo Village, measuring 164,318 m², while in Batu Kalasi Island, it only reached 136,901 m². The findings underscore the need for tailored conservation strategies for seagrass ecosystems, in particular to address the specific challenges observed at each site, emphasizing the importance of understanding and preserving diverse coastal environments.

Plasma-enabled growth of vertically oriented carbon nanostructures for AC line filtering capacitors

Self-standing vertically oriented carbon nanostructures (VCNs) were synthesized using a large-scale microwave plasma under low-pressure conditions, employing methane as a carbon precursor. The influence of plasma operational and substrate conditions on nanostructure growth and morphology were systematically studied. Furthermore, post-synthesis N-doping of VCNs with nitrogen content of 2.4 at% N was achieved using an Ar-N2 microwave plasma. Plasma-enabled direct deposition of VCNs, both doped and un-doped, onto nickel foils has been accomplished. The assessment of the developed nanostructures as electrodes in high-frequency AC filtering capacitors, has demonstrated an overall capacitance of approximately 480 µF at 100 Hz, with a cut-off frequency of 4 kHz for a phase angle of −45°. The excellent electrochemical performance can be attributed to the appropriate structural and morphological properties peculiar for the directly deposited on nickel foil VCNs providing binder-free electrode fabrication, thus enhancing the electrode’s conductivity and charge transfer kinetics. This plasma-enabled approach for electrode design on a large scale, coupled with excellent filtering performance, paves the way for many applications in high-frequency scenarios, offering an environmentally friendly alternative to conventional electrolytic capacitors.

Cracking Behavior of Environmental Barrier Coatings/CMC System Using Acoustic Emission and Digital Image Correlation

Abstract An investigation into the cracking behavior of advanced environmental barrier coating / woven SiC/SiC ceramic matrix composite (CMC) system under uniaxial tension testing was performed in this study. The effect of substrate (CMC) condition on the coating behavior was also studied. Acoustic emission (AE) and digital image correlation (DIC) were implemented as health monitoring techniques to gain detailed insights into the fracture process of the coating and to identify the origin and location of the fracture events. Fluorescent penetrant inspection was used in-situ in some cases to help identify cracks. Post-test microscopy was performed to correlate the results with DIC and AE. It was evident that for the as-produced woven substrate, the EBC coating cracked prior to substrate cracking; however, for the altered surface substrate, the CMC substrate formed matrix cracks prior to the EBC coating.