Organic Aggregates Research Articles

Comparison of Matrix Product State and Multiconfiguration Time-Dependent Hartree Methods for Nonadiabatic Dynamics of Exciton Dissociation.

The excited-state dynamics of organic molecules, molecular aggregates, and donor-acceptor clusters is typically governed by the interplay of electronic excitations and, due to their flexibility and soft bonding, by the interaction with their vibrations. This interaction in these systems can be characterized by a few relevant electronic states that are coupled to numerous vibrational normal modes, encompassing a vast configurational space of the molecules. The full quantum simulation of these type of systems has been long dominated by the multiconfiguration time-dependent Hartree (MCTDH) approach and its multilayer variants, which are considered the gold standard in the presence of electron-vibration coupling with a large number of modes. Recently, also the matrix product state ansatz (MPS) with appropriate time-evolution schemes has been applied to these types of Hamiltonians. In this article, we provide a numerical comparison of excited-state dynamics between the MCTDH and MPS approaches for two electron-vibration coupled systems. Notably, we consider two models for exciton dissociation at a P3HT:PCBM heterojunction, comprising two electronic states and 100 vibrational modes, and 26 electronic states and 113 vibrational modes, respectively. While both methods agree very well for the first model, more pronounced deviations are found for the second model. We trace back the divergence between the methods to the different way entanglement is treated.

Soil Organic Carbon and Aggregate Associated Changes in Three Subtropical Evergreen Forest Ecosystems of China

Soil Organic Carbon and Aggregate Associated Changes in Three Subtropical Evergreen Forest Ecosystems of China

Exploring Photophysical Properties of Organic Doped Polymeric Aggregates for Detecting Relevant Inorganic Pyrophosphate: A Pathway to Sustainable Development

Pyrophosphate (PPi) is an important environmentally and biologically relevant analyte and its easy and efficient detection is crucial for sustainable development. So, here we designed and synthesized organic-doped polymeric aggregates varying the signaling units (pyrene and anthracene) and examined their photophysical properties. By altering the signaling unit while keeping the polymeric backbone intact, we observed aggregate changes and studied their optical response with inorganic pyrophosphate (PPi). Among these probes, PYR-PEI exhibited a superior turn-off response(~6.1-fold) towards PPi in aqueous media whereas the other two probes ANH-PEI and PYR-PAH showed less response. The distinct response to PPi was primarily determined by electrostatic interaction and aggregate nature. The limit of detection (LOD) for PPi using the PYR-PEI probe was found to be 4.2 ppm, which is below the maximum allowable concentration of phosphate in surface water set by the World Health Organization (WHO) at 5mg/l. The quantification limit (LOQ) for PPi sensing was observed to be 14.27 ppm. Additionally, the PYR-PEI probe showed different fluorogenic responses (ratio-metric change) in the presence of anionic surfactant sodium dodecyl sulfate (SDS), and this resultant adduct was used for the PPi detection. The formation of premicellar aggregates between them drove the difference in the fluorogenic response with PYR-PEI and surfactant. Then the PYR-PEI composite was employed to detect PPi in spiked soil solution. Finally, chemically modified paper strips were prepared for the easy, fast, and on-location detection of PPi present in real-life samples.

Effects of Long-Term Fenced Enclosure on Soil Physicochemical Properties and Infiltration Ability in Grasslands of Yunwu Mountain, China

Fenced enclosures, a proven strategy for restoring degraded grassland, have been widely implemented. However, recent climate trends of warming and drying, accompanied by increased extreme rainfall, have heightened soil erosion risks. It is crucial to assess the long-term effectiveness of fenced enclosures on grassland restoration and their impact on soil physicochemical properties and water infiltration capacity. This study investigated the effects of enclosure duration on soil organic matter, aggregate composition and stability, and infiltration capacity in Yunwu Mountain Grassland Nature Reserve, comparing grasslands with enclosure durations of 2, 14, 30, and 39 years. Results showed that grasslands enclosed for 14, 30, and 39 years had infiltration rates increased by 20.66%, 152.03%, and 61.19%, respectively, compared to those enclosed for only 2 years. After 30 years of enclosure, soil quality reached its optimum, with the highest root biomass, soil organic matter, aggregate stability, and a notably superior infiltration rate. The findings suggest that long-term fenced enclosures facilitate grassland vegetation restoration and enhance soil infiltration capacity, with the most significant improvement observed at the 30-year enclosure milestone, followed by a gradual decline in this effect.

Influence of Substituents on the Vectorial Difference Static Dipole Upon Excitation in Synthetic Bacteriochlorins.

Organic dye aggregates have been shown to exhibit exciton delocalization in natural and synthetic systems. Such dye aggregates show promise in the emerging area of quantum information science (QIS). We believe that the difference in static dipole (Δd) is an essential dye parameter in the development of molecular QIS systems. However, a foundational understanding of the structural factors influencing Δd remains elusive. Bacteriochlorins play a vital role in photosynthesis due to their exceptional photophysical properties. Therefore, bacteriochlorins are particularly suitable dyes for the construction of aggregate systems for QIS. Synthetic bacteriochlorins further offer stability and tunability via chemical modifications. Here, the influence of substituents on the Δd of monomeric (nonaggregated) dyes was investigated via density functional theory (DFT) and time-dependent (TD)DFT in a set of 5-methoxybacteriochlorins progressively substituted with ethynyl, phenyl, and phenylethynyl substituents at the 3,13 and 3,13,15 positions of the macrocycle. Symmetrically substituted 5-methoxybacteriochlorins were shown to have the largest Δd. The increase in Δd in the series of dyes was largely due to changes in the orientation of the static dipole upon excitation rather than large changes in magnitude. In addition, the transition dipole (μ) and the angle between Δd and μ (ζ) were calculated. Three 5-methoxybacteriochlorins with large predicted Δd and μ values were synthesized and characterized spectroscopically. The trend in Δd values empirically determined using the solvatochromic Stokes shift method was comparable to the DFT calculations.

Old-growth Ficus trees provide soil water and carbon storage to urban greenspaces in a Brazilian metropolis

Urban flooding has been considered one of the most severe natural disasters around the world, and urban greenspaces can provide important flood regulation ecosystem services. In Belo Horizonte (Brazil), the woody vegetation, especially the old-growth Ficus trees, appears to protect an urban park against the flooding of the Arrudas river. Thus, we compared the soil water content, soil water-holding capacity, soil aggregation and porosity among a highly permeable urban park planted with herbaceous and woody species, including Ficus, a semi-permeable parking lot with only Ficus and an impermeable site without trees (Disturbed Site-DS). The soil water content and water holding capacity of the urban park did not differ from that of the Ficus site, but it was lower than DS. These results were correlated with soil organic matter (SOM) content, soil aggregation and porosity, suggesting that Ficus trees play an important role in the hydrological cycle. To understand how the Fiscus species provide such soil permeability, we compared the aboveground plant biomass, soil fertility and soil carbon sequestration (total soil carbon, soil organic matter, humic and fulvic acids and soil isotopic δ13 C) in plots with Ficus and without this species within the park as well as in a preserved urban forest and a disturbed square. The outstanding plant biomass produced by Ficus species explained the high soil carbon sequestration, particularly in humic organic matter, favouring soil aggregation, porosity and water retention. Therefore, Ficus species may be considered an exceptional C-sequestering species, contributing for soil stabilization and the hydrological cycle in urban greenspaces.

The role of agroecological systems in cation interaction and aggregate formation in drylands of northeastern Brazil

Agroecological production systems are used in dryland agroecosystems. Therefore, it is necessary to verify their contributions, especially with regard to the functionality of soil attributes. From this perspective, this study aimed to evaluate the influence of soil use and management on the structural, hydraulic, and chemical attributes of a Haplic Cambisol in the Apodi Plateau, RN, Brazil. The experimental design adopted was completely randomized, with treatments distributed in a 5×3 factorial arrangement corresponding to five sampling locations (fruit farming, horticulture, agroecological, intercropping of Zea mays and Vigna unguiculata (L.) Walp), and three soil layers (0.00-0.10, 0.10-0.20, and 0.20-0.30 m), in addition to the correlation matrix and principal component analysis as multivariate statistical techniques. The parameters evaluated included soil pH, nutrient levels (available P, K+, Ca2+, and Mg2+), total organic carbon, soil density, total porosity, field capacity, permanent wilting point, available water, aggregation, aggregate stability, weighted mean diameter of aggregates, and the content of organic matter, Ca2+, and Mg2+ in different soil aggregate classes. The study concluded that continuous soil use practices such as intercropping Z. mays and V. unguiculata and horticulture significantly reduce nutrient availability, organic carbon content, moisture, and soil aggregation. However, areas under agroecological management and fruit cultivation, which involve minimal soil disturbance, promote the improvement of these properties.

A comparative analysis of soil organic carbon stock and soil aggregation in two crop sequences in the Rolling Pampa (Argentina)

Understanding how farming practices affect soil organic carbon (SOC) accumulation is essential for sustainable agriculture. Agronomic decisions, such as crop sequence, significantly influence various soil properties. However, the overall benefits of crop rotation on soil structure and SOC storage remain uncertain. We compared the effects of soybean (Glycine max L.) monocropping with a three-year crop rotation comprising wheat (Triticum aestivum L.)/soybean double crop, maize (Zea mays L.), and soybean on the vertical distribution of SOC up to one metre depth. Additionally, we examined carbon accumulation as particulate organic matter-carbon (POM-C), soil aggregation, and structural stability in the topsoil. Compared to monocropping, crop rotation increased SOC concentrations (19 vs. 16 gC kg soil⁻¹), stock (12 vs. 10.7 MgC ha⁻¹), and POM-C content (6 vs. 3.2 gC kg soil⁻¹) in the first 5 cm of soil. At 20–65 cm depth, rotation showed a marginal increment of SOC stock with respect to soybean monocropping. The increased surface SOC content in the rotation positively affected the POM-C content and macro-aggregation. However, soil structural stability showed a tendency to be higher in the monocropping, especially at a depth of 5–20 cm. Overall, crop rotation demonstrated potential for enhanced carbon sequestration in temperate agroecosystems within three years, despite not significantly improving soil structural stability.

Beyond the Bloom: Unraveling the Diversity, Overlap, and Stability of Free-Living and Particle-Attached Bacterial Communities in a Cyanobacteria-Dominated Hypereutrophic Lake

In aquatic ecosystems with low nutrient levels, organic aggregates (OAs) act as nutrient hotspots, hosting a diverse range of microbial species compared to those in the water column. Lake eutrophication, marked by intensified and prolonged cyanobacterial blooms, significantly impacts material and energy cycling processes, potentially altering the ecological traits of both free-living (FL) and particle-attached (PA) bacteria. However, the extent to which observed patterns of FL and PA bacterial diversity, community assembly, and stability extend to hypereutrophic lakes remains understudied. To address this gap, we investigated bacterial diversity, composition, assembly processes, and stability within hypereutrophic Lake Xingyun. Our results revealed that FL bacterial communities exhibited higher α-diversity than PA counterparts, coupled with discernible taxonomic compositions. Both bacterial communities showed distinct seasonality, influenced by cyanobacterial bloom intensity. Environmental factors accounted for 71.1% and 54.2% of the variation among FL and PA bacteria, respectively. The assembly of the PA bacterial community was predominantly stochastic, while FL assembly was more deterministic. The FL network demonstrated greater stability, complexity, and negative interactions, indicative of competitive relationships, while the PA network showed a prevalence of positive correlations, suggesting mutualistic interactions. Importantly, these findings differ from observations in oligotrophic, mesotrophic, and eutrophic lakes. Overall, this research provides valuable insights into the interplay among bacterial fractions, enhancing our understanding of nutrient status and cyanobacterial blooms in shaping bacterial communities.

Effect of soil management on carbon stock and soil aggregation in an area of natural regeneration and surrounding systems in the Atlantic Forest biome

This study aimed to quantify total organic carbon (TOC), carbon of humic substances (HS), and their stocks and evaluate the soil structural stability of areas with different uses under sandy loam soil texture. Soil samples were collected from managed areas and a reference area: Permanent Pasture (PP), No-Till (NT), Private Natural Heritage Reserve in the process of natural regeneration (PNHR) and Native Forest (FN). Dry mass analysis, carbon stock quantification, chemical fractionation of soil organic matter and soil aggregation were carried out. The NF area had the highest deposition of litter mass (ML). The PP and NT areas had the highest bulk density (Bd). TOC and Stock-C contents were higher in PNHR, followed by NF, and stratification index (STRATI) was also higher in the regeneration area. The NT, PNHR, and NF areas had a higher proportion of carbon fulvic acid fraction (C-FA) than carbon humic acid fraction (C-HA), but the fraction with the highest representation in all areas was carbon humin fraction (C-HUM). The PP, PNHR, and NF areas obtained the best aggregate stability indicators, as well as a higher proportion of macroaggregates, with the NT area having low aggregate stability. Recovery of C contents was observed in recent years in the area of PNHR, leading to a greater storage of C, which shows a quantitative recovery of C in the soil in this area after four years of natural regeneration. Furthermore, the PP and NT areas present a lower capacity for C sequestration, mainly due to the management conditions. Keywords: aggregate stability, climate change, crop production, soil quality.

Frontispiz: Responsive Organic Fluorescent Aggregates Based on Ion‐π Interactions Away from Fluorescent Conjugated Groups

Frontispiz: Responsive Organic Fluorescent Aggregates Based on Ion‐π Interactions Away from Fluorescent Conjugated Groups

Frontispiece: Responsive Organic Fluorescent Aggregates Based on Ion‐π Interactions Away from Fluorescent Conjugated Groups

Frontispiece: Responsive Organic Fluorescent Aggregates Based on Ion‐π Interactions Away from Fluorescent Conjugated Groups

Eco-Friendly 3D-Printed Concrete Made with Waste and Organic Artificial Aggregates.

In this research, the results of an experimental study on the use of three alternative components for creating artificial aggregates (AAs) (granules) and their usage in 3D-printed concrete (3DPC) are examined. This study combines AAs made from organic components like hemp shives (HSs), pyrolyzed coal (charcoal), waste/municipal solid waste incinerator bottom slag (BS), and a mix of a reference 3DPC with the aforementioned AAs. Particularly, to enhance these properties to make low-carbon 3DPC, in this research, the potential of using AAs as lightweight aggregates was increased to 14% in terms of the mass of the concrete. Each mix was tested in terms of its printability via a preliminary test in a 3D printing laboratory. For an additional comparison with the aforementioned cases, 3DPC was mixed with unprocessed hemp shives, charcoal, and BS. Furthermore, their strength was measured at 28 days, and lastly, their durability parameters and shrinkage were experimentally investigated. Cross-sections of the fragments were studied under a scanning electron microscope. In this study, we achieved improvements in the mechanical properties of AAs for their development and implementation as an innovative way to reduce carbon in 3DPC.

Centimetre scale functional dispersal limitation of freshwater copiotrophs.

The freshwater microbiome harbours numerous copiotrophic bacteria that rapidly respond to elevated substrate concentrations. We hypothesized that their high centimetre-scale beta diversity in lake water translates into pronounced metabolic variability, and that a large fraction of microbial 'metabolic potential' originates from point sources such as fragile organic aggregates. Three experiments were conducted in pre-alpine Lake Zurich over the course of a harmful cyanobacterial bloom: Spatially explicit 9 ml 'syringe' samples were collected in situ at centimetre distances along with equally sized 'mixed' samples drawn from pre-homogenized lake water and incubated in BIOLOG EcoPlate substrate arrays. Fewer compounds promoted bacterial growth in the syringe than in the mixed samples, in particular during the pre- and late bloom periods. Community analysis of enrichments on three frequently utilized substrates revealed both pronounced heterogeneity and functional redundancy. Bacterial consortia had higher richness in mixed than in syringe samples and differed in composition. Members of the Enterobacter cloacae complex dominated the EcoPlate assemblages during the mid-bloom period irrespective of treatment or substrate. We conclude that small-scale functional dispersal limitation among free-living copiotrophs in lake water reduces local biotransformation potential, and that lacustrine blooms of harmful cyanobacteria can be environmental reservoirs for metabolically versatile potential pathogens.

Substantial and Rapid Increase in Soil Health across Crops with Conversion from Conventional to Regenerative Practices

Interest in soil health is growing, though the speed and effectiveness of management practices in improving it are uncertain. We measured biological, chemical, and physical indicators of soil health within a working farm zero, five, and nine years after transitioning from regular applications of inorganic fertilizers and pesticides to cover cropping, compost additions, organic amendments, and rotational grazing. We quantified microbial biomass and composition, soil organic matter (SOM), nutrient availabilities, and water stable aggregates in an avocado orchard, a citrus orchard, a pasture, and a vegetable garden. We found substantial and consistent increases in SOM, water stable aggregates, and microbial biomass, especially during the first five years, whereas nutrient availabilities showed no consistent change. Fungal and bacterial communities shifted but not fungal–bacterial biomass ratios or richness. However, fungal guilds responded differently to shifts in management. The biomass of arbuscular mycorrhizal fungi increased in most crops, and fungal saprotroph relative abundance and richness generally increased, whereas putative fungal pathogens showed the opposite response. Overall, we found substantial and rapid increases in indicators associated with improved soil health following the transition from conventional to regenerative management.

Responsive Organic Fluorescent Aggregates Based on Ion‐π Interactions Away from Fluorescent Conjugated Groups

AbstractResponsive organic luminescent aggregates have a wide range of application fields, but currently there is still a lack of reasonable molecular design strategies. Introducing ion‐π interactions into molecules can effectively alter their luminescent properties. However, current research typically focuses on ion localization at luminescent conjugated groups with the strong interaction forces. In this work, we introduce the flexible alkoxy chain spacers between fluorescent conjugated groups and ion‐π interaction sites, and then adjust the fluorescence performance of the molecule by changing the strength of ion‐π interactions. Bromine ion‐based molecules with strong ion‐π interactions exhibit high and stable fluorescence quantum yields in crystals and amorphous powders under the external stimuli. Hexafluorophosphate ion‐based molecules with weak ion‐π interactions have the high fluorescence quantum yield in crystals and very low fluorescence quantum yield in amorphous powders, showing variable fluorescence intensities under external stimuli. This demonstrates a new class of responsive organic luminescent solid‐state materials.

Responsive Organic Fluorescent Aggregates Based on Ion-π Interactions Away from Fluorescent Conjugated Groups.

Responsive organic luminescent aggregates have a wide range of application fields, but currently there is still a lack of reasonable molecular design strategies. Introducing ion-π interactions into molecules can effectively alter their luminescent properties. However, current research typically focuses on ion localization at luminescent conjugated groups with the strong interaction forces. In this work, we introduce the flexible alkoxy chain spacers between fluorescent conjugated groups and ion-π interaction sites, and then adjust the fluorescence performance of the molecule by changing the strength of ion-π interactions. Bromine ion-based molecules with strong ion-π interactions exhibit high and stable fluorescence quantum yields in crystals and amorphous powders under the external stimuli. Hexafluorophosphate ion-based molecules with weak ion-π interactions have the high fluorescence quantum yield in crystals and very low fluorescence quantum yield in amorphous powders, showing variable fluorescence intensities under external stimuli. This demonstrates a new class of responsive organic luminescent solid-state materials.

Origin and significance of macroscopic organic aggregates from the lacustrine Aptian Crato Konservat-Lagerstätte

The Crato Konservat-Lagerstätte is one of the main Mesozoic fossil sites from Gondwana, recording a wide diversity of terrestrial and non-marine aquatic fossils of great paleobiological and evolutionary significance. This conservation deposit is recorded in a 9 m-thick interval of laminite, microbialite, and grainstone deposited in a lake system with variable water level, alternating moments of hypersaline and freshwater conditions. Despite numerous studies describing new species of plants, arthropods, fish, pterosaurs, birds, and many others, there remains a significant gap in our understanding of the most common and archetypal fossils, which are the rod-shaped macrofossils found on bedding surfaces in distinct stratigraphic intervals of the Crato Konservat-Lagerstätte. The rod-shaped macrofossils are up to 1.6 cm-long and 0.1 cm-wide, straight to curved compressions that preserve pyritized microfossils. Here we interpret the rod-shaped macrofossils as macroscopic organic aggregates that sank into the lakebed in a process called lake snow. During high organic productivity periods in the epilimnion, planktonic organisms thrived and produced exopolymers responsible for aggregation. Their concentrations in the limestone bedding planes reflect intensity of lake snow and environmental seasonality. Aggregates are prolate particles that are commonly oriented, suggesting their transport as bedload for short distances, which was facilitated by biostabilization by microbes and their exopolymers. Finally, pyritization was mediated by microbial communities living in the lakebed.

The Influence of Different Land Use Practices on Specific Physical Characteristics of Soil in Gaya, a Region within the Savanna Ecosystem in Nigeria

This study examines the impact of various land use types on specific physical properties of soil at the Kano University of Science and Technology Research Farm in Gaya, Gaya L.G.A., Kano State, Nigeria. The four agricultural land uses investigated are cropland, forest, grazing, and plantation land. Soil samples were randomly collected from two depths (0-15 cm and 15-30 cm), with five samples from each depth per land use type, resulting in 40 samples. Bulk densities were measured using the core method. The results indicated no significant effect (Fpr > 0.05) of land use on bulk density and porosity. However, bulk density values exhibited an increasing trend: cropland (1.602 g/cm3) < forest land (1.667 g/cm3) < plantation land (1.669 g/cm3) < grazing land (1.69 g/cm3). Grazing land had the highest mean bulk density, while cropland had the lowest. At 0-15 cm depth, plantation land had the highest mean bulk density (1.698 g/cm3), and cropland had the lowest (1.547 g/cm3). At a depth of 15-30 cm, forest land had the highest mean bulk density (1.767 g/cm3), while plantation land had the lowest (1.641 g/cm3). Total porosity showed an increasing trend from grazing land (30.8%) to plantation land (33.6%), cropland (34.3%), and forest land (37.7%). Factors such as organic matter content, aggregate size, and soil depth influenced the bulk density and porosity characteristics. Overall, bulk density was higher than standard values, indicating compaction: sandy soils were too compact, loamy soils were very compact, and clay soils were highly compact. Total porosity generally fell within the moderate range, and particle density was within the normal acceptable range of 2.65 g/cm3.

Enhanced sinks of polystyrene nanoplastics (PSNPs) in marine sediment compared to freshwater sediment: Influencing factors and mechanisms

The difference in the transport behaviors of nanoplastics consistently assistant with their toxicities to benthic and other aquatic organisms is still unclear between freshwater and marine sediments. Here, the mobilities of polystyrene nanoplastics (PSNPs) and key environmental factors including salinity and humic acid (HA) were systematically studied. In the sand column experiments, both tested PSNPs in the freshwater system (100 nm NPs (100NPs): 90.15 %; 500 nm NPs (500NPs): 54.22 %) presented much higher penetration ratio than in the marine system (100NPs: 8.09 %; 500NPs: 19.04 %). The addition of marine sediment with a smaller median grain diameter caused a much more apparent decline in NPs mobility (100NPs: from 8.09 % to 1.85 %; 500NPs: from 19.04 % to 3.51 %) than that containing freshwater sediment (100NPs: from 90.15 % to 83.56 %; 500NPs: from 54.22 % to 41.63 %). Interestingly, adding HA obviously led to decreased and slightly increased mobilities for NPs in freshwater systems, but dramatically improved performance for NPs in marine systems. Electrostatic and steric repulsions, corresponding to alteration of zeta potential and hydrodynamic diameter of NPs and sands, as well as minerals owing to adsorption of dissolved organic matter (DOM) and aggregations from varied salinity, are responsible for the mobility difference.