Decay Pattern Research Articles

Environmental DNA unveiling the fish community structure and diversity features in the Yangtze River basin

Fish, as top predators in aquatic ecosystems, play an important role in maintaining the structure and functioning of these ecosystems, making their diversity a topic of great interest. This study focused on the Yangtze River Basin to investigate the fish community structure and diversity using environmental DNA (eDNA) technology. The results showed that a total of 71616 fish operational taxonomic units (OTUs) and 90 fish belonging to 23 families were detected, with the Cyprinidae family being the dominant group, followed by the Cobitidae, Amblycipitidae, etc. Compared to historical traditional morphological fish surveys, the quantity of fish detected using eDNA was relatively low, but the overall distribution pattern of fish communities was generally consistent. The highest fish Shannon-Wiener diversity index in the Yangtze River Basin sites reaches 2.60 with an average value of 1.25. The fish diversity index was higher in the downstream compared to the middle and upstream regions, and there were significant differences among different sampling sites. Significant environmental factors influencing α-diversity included chlorophyll-a, chemical oxygen demand, dissolved oxygen, total nitrogen, and elevation. Non-metric multidimensional scaling (NMDS) analysis revealed significant differences in fish community composition between the upstream and middle/lower reaches of the Yangtze River, while the composition of fish communities in the middle and lower reaches was more similar. Redundancy analysis (RDA) indicated that total organic carbon (TOC) was positively correlated with fish community distribution in the upstream, while water temperature and NO3–N were negatively correlated with fish distribution in the upstream. NH3–N and CODMn were negatively correlated with fish distribution in the middle and downstream regions, indicating a relatively severe water pollution in these areas. Additionally, fish communities in the Yangtze River displayed a typical distance decay pattern.

Experimental and numerical investigation of leakage and diffusion accidents based on nuclear energy hydrogen production system

The high-temperature gas-cooled reactor, as a fourth-generation nuclear power system, possesses a distinct advantage of high core outlet temperature, making it a viable option for large-scale, low-carbon hydrogen production. However, before this technology can be widely adopted, it is crucial to conduct a safety assessment of the nuclear hydrogen production system, considering the unique physical and chemical properties of hydrogen. This study aimed to address this requirement by implementing two experimental setups, utilizing helium as a substitute for hydrogen. Concentration distribution measurements were performed in both open spaces and inside a wind tunnel. The concentration decay rates were found to be 0.177 under windless conditions and 0.313 in windy conditions. Subsequently, numerical models were employed to validate the feasibility of leakage and diffusion calculations for subsonic leakage jets and high-pressure underexpanded leakage jets, respectively. Moreover, multiple simulation calculations were conducted to design leakage accident scenarios based on the nuclear hydrogen production system. The corresponding concentration decay patterns were summarized, and evaluation relational expressions were proposed to determine diffusion distance and explosion distance for the nuclear energy hydrogen production system, accounting for the influence of buoyancy effects and incorporating the average concentration of combustible hydrogen clouds. Lastly, considering the worst-case accident conditions of the current system, a fan reverse blowing scheme was suggested to mitigate safety risks. The findings indicated that this scheme could potentially reduce the separation distance from 479 m to 183 m. Overall, this research contributes valuable insights into the safety assessment and design of nuclear hydrogen production systems.

A nitrifier‐enriched microbial community contributes to the degradation of environmental DNA

AbstractEnvironmental DNA (eDNA) surveys are a promising alternative to traditional monitoring of invasive species, rare species, and biodiversity. Detecting organism‐specific eDNA reduces the need to collect physical specimens for population estimates, and the high sensitivity of eDNA assays may improve detection of rare or cryptic species. However, correlating estimated concentrations of eDNA with species abundance can be difficult due to the many abiotic and biotic factors that influence eDNA persistence and degradation. Here, we assessed the impact of a nitrifier‐enriched microbial (NEM) community on the persistence and degradation of Hypophthalmichthys molitrix (silver carp) milt eDNA using experimental aquatic mesocosms and a quantitative PCR approach. The NEM community was cultured from combined sediment and water samples collected from a golf course pond in Columbia, Missouri (USA), and experiments were conducted in the dark at 22°C. We found that the NEM community transformed organic nitrogen from silver carp milt to measurable amounts of nitrate, both in the presence and absence of ammonia nitrogen. Additionally, regardless of ammonia availability, milt eDNA followed a one‐phase exponential decay pattern after an initial 24‐h plateau in the presence of the NEM community. However, milt eDNA had a shorter half‐life (12.5 h) in the absence of exogenous ammonia compared to when ammonia was present (15 h). In sterile mesocosms, eDNA was stable during the 72‐h experiment. Together, these results suggest that the presence of microorganisms is necessary for short‐term degradation of eDNA. Furthermore, nitrifying microbial communities, which are ubiquitous in most soil and water environments, could limit eDNA persistence in the environment. Understanding the contributions of environmental microbial communities will allow more confidence in sampling design and eDNA result interpretations for biodiversity management applications.

Caries clusters at lesion-severity thresholds: A Sierra Leone case study.

Despite being almost entirely preventable, globally, dental caries is extremely prevalent. Moreover, dental caries will continue to present an even larger challenge for lower income countries, particularly those in the African context, as they transition to a more Western diet. Hence, epidemiological data providing insight into disease patterns and trends is critical to inform public health action. The purpose of this study was to examine dental caries clusters by caries detection threshold among 15-year-old adolescents in Sierra Leone, using data from the latest national survey, and to explore associated sociodemographic factors. This paper presents a secondary analysis of oral health data on 490 15-year-olds from the Sierra Leone national oral health survey of schoolchildren. Hierarchical cluster analysis of dental caries experience was conducted across all surfaces at four decay detection thresholds using the International Caries Detection and Assessment System (ICDAS) (clinical: ICDAS 2-6, cavitated: ICDAS 3-6, obvious: ICDAS 4-6 and extensive obvious: ICDAS 5-6 decay) across the four regions of Sierra Leone. Ordered logistic regression was used to estimate the association of sociodemographic factors with generated clusters relating to clinical and obvious decay experience. These are of both clinical and epidemiological relevance. A 3-cluster decay pattern representing a 'low' to 'high' decay experience distribution was observed under each decay detection threshold across surfaces. For clinical decay (including visual enamel caries), 28.8% had low, 55.1% medium and 15.9% high caries status. In the adjusted model, the only significant risk factor across obvious and clinical decay thresholds was region, with adolescents outside the Western region more likely to experience decay. This study suggests that adolescents in Sierra Leone fall into three distinct caries clusters: low, medium to high decay experience distribution, regardless of decay threshold. It reinforces the importance of recognizing dental caries detection thresholds and the use of contemporary epidemiological methodology. This suggests that adolescents outside the Western region are likely to have higher caries experience. The data also provides insight to the nature of adolescents in each cluster and should help to inform policy and planning of the integration of oral health into primary care and school systems.

Partial Discharge-Originated Deterioration of Insulating Material Investigated by Surface-Resistance and Potential Mapping

The endurance of medium- and high-voltage electrical insulation is a key reliability element in a broad spectrum of applications that cover transmission and distribution levels, the transportation segment, the industrial environment, and power electronics-based energy-conversion systems. The high electric-field stress and high-frequency switching phenomena as well as the impact of environmental conditions lead to the occurrence of partial discharges (PD) and the subsequent deterioration of electrical insulation. Partial discharges usually occur inside solid insulation materials in tiny voids that may either be located adjacent to the electrodes or in the bulk of dielectric material. This effect refers to both AC and DC systems; however, AC voltage is usually much more intensive as compared to DC voltage. This paper describes a novel combined approach based on surface-resistance and potential mapping to reveal the effects of internal processes and the deterioration of insulating material due to the actions of partial discharges. To realize the research objective, the following two-step approach was proposed. Multi-point resistance mapping enables us to identify the spots of discharge channels, manifesting a-few-orders-of-magnitude-lower surface resistance as compared to untreated areas. In addition, surface-potential mapping that was stimulated by corona-charge deposition reflects quasi-equipotential clusters and the related polarity-dependent dynamics of charge decay. A high spatial and temporal resolution allows for the precise mapping and tracing of decay patterns. Experiments were carried out on polyethylene (PE) and Nomex specimens that contained embedded voids. During PD events, the effective discharge areas are identified along with the memory effects that originate from the accumulation of surface charges. Long-term aging processes may drive the formation of channels that are initiated from the deteriorated micro clusters, in turn, penetrating the bulk isolation. The presented methodology and experimental results extend the insight into PD mechanisms and internal surface processes.

A double-perovskite Mn4+-doped Sr2ScNbO6 phosphor for indoor plant growth lighting

To find suitable far-red-emitting phosphors in the field of plant lighting, a series of double-perovskite Mn4+-doped Sr2ScNbO6 (abbreviated as SSNO: Mn4+) phosphors were prepared and their crystal structure, morphology, and photoluminescence were analyzed. SSNO: Mn4+ phosphor produces far-red light with a peak wavelength of 702 nm. And this phosphor has two unique efficient broad excitation bands located respectively around 313 nm and 357 nm in the near-ultraviolet (UV) regions. The optimal doping concentration of Mn4+ ions, the dependence of luminescence on temperature, and the decay pattern of the samples were investigated. In addition, the light emitting diode (LED) was prepared by the combination of a 365 nm chip and SSNO: Mn4+ phosphor, which can emit bright far-red light. Therefore, SSNO: Mn4+ phosphors are expected to be applied in field of indoor plant cultivation.

Decay of human immunodeficiency virus (HIV) RNA in seminal plasma and rectal fluid in treatment-naïve adults starting antiretroviral therapy with dolutegravir plus lamivudine or bictegravir/emtricitabine/tenofovir alafenamide.

Decay of HIV in seminal plasma (SP) and rectal fluid (RF) has not yet been described for the antiretroviral combination of dolutegravir(DTG) + lamivudine(3TC). Randomized multicenter pilot trial. Antiretroviral-naive males were randomized (2:1) to DTG + 3TC or bictegravir(BIC)/emtricitabine(FTC)/tenofovir alafenamide(TAF). HIV-1 RNA was measured in blood plasma (BP), SP, and RF at baseline, days 3, 7, 14, 28, and weeks 12 and 24. Of 25 individuals enrolled, 24 completed the study (DTG + 3TC n = 16, BIC/FTC/TAF n = 8). No significant differences were observed between groups for median decline in HIV-1 RNA from baseline at each time point or median time to achieve HIV-1 RNA <20 copies/mL in BP, SP, and RF.HIV-1 RNA decay patterns were compared in individuals receiving DTG + 3TC. Despite significantly higher percentages for changes from baseline in BP, median times to HIV-1 RNA suppression were shorter in SP (7 days [0; 8.75]) and in RF (10.5 days [3; 17.5]) than in BP (28 days [14; 84]) (p < 0.001). Comparable HIV-1 RNA decay in BP, SP, and RF was observed between DTG + 3TC and BIC/F/TAF. As shown with triple-drug integrase inhibitor-based regimens, rapid HIV-1 RNA suppression in SP and RF is achieved with DTG + 3TC, despite decay patterns differing from those of BP.

Investigation of Nd3+:Y2Si2O7 Phosphors Using Photoluminescence and Positron Annihilation Lifetime Spectroscopy

Neodymium-doped Y2Si2O7 nanopowders were synthesized by sol-gel and annealed under varying annealing temperature conditions. The phase transformation of Y2Si2O7 and the crystalline size change were observed with annealing temperature. Photoluminescence and the decay patterns of the 4F3/2→ 4I9/2, 4I11/2, and 4I13/2 transitions were examined to reveal the spectroscopic characteristics of the powders. The spectral outputs of Nd3+:Y2Si2O7 phosphors remain strongly connected to the phase properties of Y2Si2O7. The positron lifetimes (τ 2, τ 3, and τ 4) and intensities (I 2, I 3, and I 4) obtained by positron annihilation lifetime spectroscopy were discussed for neodymium-doped Y2Si2O7 phosphors to relate the structural and boundary changes in terms of the phases and molar contents of the Nd3+ ions. The τ 2 and I 2 components were related to the structural open space in the grain, the τ 3 and I 3 components were correlated with vacancy-like defects in the grain boundaries, and the τ 4 and I 4 components were associated with vacancy defects in the grain, together with the effect of the increasing content of the Nd3+ ions.

Research on the influences of motion characteristics of jetting projectile charge under water

Shaped charge warhead is important for enhancing the damage performance of underwater weapons. This paper used finite element analysis software and based on JPC water penetration experiments to examine the influence of liner parameters (wall thickness, material), charge aspect ratio, and stand-off distance on the movement characteristics of JPC in water. The findings reveal that the head diameter of the JPC increases and experiences significant erosion after entering the water, the effective length of the JPC in water undergoes two distinct phases: a growth phase and a decrease phase, with the velocity of the JPC decaying exponentially. Increasing the liner thickness, stand-off distance and the charge aspect ratio can improve the erosion resistance and the velocity retention capacity of the JPC. The optimal ranges for liner thickness and stand-off distance are 0.0363Dk to 0.0545Dk (Dk is the charge diameter), the stand-off distance should be within 1.0Dk. After the charge aspect ratio higher than 1.25, the charge structure exerts minimal influence the movement characteristics of the JPC in water. Material density plays a crucial role in the velocity decay pattern of the JPC during penetration. JPC with higher densities exhibit superior velocity retention capabilities in water, with the velocity decay pattern converging if the densities are similar. Consequently, copper, tantalum and tungsten liners are deemed appropriate for underwater shaped charge warhead. Finally, the results will provide an important reference for the design of underwater shaped charge warhead.

Microfauna community assembly and cascading relationship with microflora in cropland ecosystems along a latitudinal gradient

Cropland ecosystems are environmentally more homogeneous than natural ecosystems due to anthropogenic management. However, it is unclear whether there is similar convergence in soil fauna diversity and community assembly in croplands with different latitudes. Therefore, the study on the latitudinal pattern and community assembly processes of soil microfauna across a transect spanning 3200 km of croplands was conducted. The results indicated that the β diversity of plant parasites, fungivores, and bacterivores showed a decreasing trend and that of omnivores-predators at higher levels followed a unimodal distribution along a latitudinal gradient. The dissimilarity of soil microfauna communities increased with geographical distance, which exhibited a strong distance decay pattern. The β diversity partitioning analysis suggested that species replacement had the greatest influence for all trophic groups, except for omnivores-predators that were driven by a combination of richness differences and species replacement. The stochastic processes shaping the microfauna assembly prevailed over deterministic processes. Ecological drift and homogenizing dispersal of the stochastic processes accounted for 50.4% and 37% of total variations respectively, and heterogeneous selection of the deterministic processes for 10%. Both soil and climatic factors had a direct impact on soil microflora and plant parasites, and indirect impact on bacterivores, fungivores, and omnivores-predators through mediating microflora communities. The partial least squares path modeling and co-occurrence analysis all showed that the soil microfauna assembly was inextricably linked to soil microflora and their network complexity exhibited a significant increasing trend along the latitudinal gradient. Further studies are needed to optimize the molecular database of soil microfauna and construct models for predicting their community distribution patterns.

The Effect of Halide Composition on the Luminescent Properties of Ternary Cesium–Copper Halide Pseudo‐Perovskite Films

AbstractTernary copper halide pseudo‐perovskites are in the forefront of research as potential active materials in light emission applications. The optoelectronic properties of these compounds can be fine‐tuned by the preparation of mixed‐halide compositions. After irradiation, self‐trapped excitonic states are formed in these materials. However, the emission from these self‐trapped states is not yet fully understood. In this work, mixed‐halide Cs3Cu2X5 films (where X: I and/or Br) are prepared by a simple spray‐coating method. Using ultraviolet photoelectron spectroscopy, the changes in optoelectronic properties are linked to the electronic structure of these materials. It is revealed that the incorporation of bromide into the lattice makes the emission process of these materials more vulnerable to trap states. By combining the different spectroscopic characterization techniques, the exact band structure of these compounds is determined, and the different processes are translated to the absolute energy scale. As an alternative excitation mechanism of self‐trapped states, α‐particles are used to induce radioluminescence response. The Cs3Cu2X5 films exhibit composite decay patterns, most likely attributed to a multitude of different trap state‐mediated recombination processes.

Enhancing solar chimney performance in urban tunnels: Investigating the impact factors through experimental and theoretical model analysis

Efficient and sustainable ventilation in urban tunnels is crucial for combating air pollution and safeguarding human health. This study investigates the design factors impacting solar chimney performance in urban tunnels to optimize ventilation efficiency. Experimental trials analyzed the effects of blockage ratio, chimney height, and solar radiation on temperature distribution and ventilation rate. The results demonstrate that increased chimney height and solar radiation positively influence airflow velocity at the chimney outlet, enhancing ventilation. The temperature rise near absorber is higher than that closed to glazing wall. Temperature distribution within the chimney follows a distinctive horizontal two-piecewise semi-parabolic decay pattern, enabling accurate prediction of temperature profiles along the cavity depth. Novel analytical models predict temperature distribution, airflow velocity, and ventilation rate within the solar chimney system, aiding precise design and optimization. Remarkably, the blockage ratio has limited impact on ventilation rate, allowing for disregarding vehicle blockage effects in solar chimney design for urban tunnels. Matching chimney width to tunnel width and ensuring a relatively high chimney height are emphasized for optimal functionality. The study holds substantial implications for ventilation system design in urban environments, promoting healthier and more sustainable cities.

Bottom Hadrochemistry in High-Energy Hadronic Collisions.

The hadrochemistry of bottom quarks (b) produced in hadronic collisions encodes valuable information on the mechanism of color neutralization in these reactions. Since the b-quark mass is much larger than the typical hadronic scale of ∼1 GeV, bb[over ¯] pair production is expected to be well separated from subsequent hadronization processes. A significantly larger fraction of b baryons has been observed in proton-proton (pp) and proton-antiproton (pp[over ¯]) reactions relative to e^{+}e^{-} collisions, challenging theoretical descriptions. We address this problem by employing a statistical hadronization approach with an augmented set of b-hadron states beyond currently measured ones, guided by the relativistic quark model and lattice-QCD computations. Assuming relative chemical equilibrium between different b-hadron yields, thermal densities are used as fragmentation weights of b quarks into various hadron species. With quark model estimates of the decay patterns of excited states, the fragmentation fractions of weakly decaying b hadrons are computed and found to agree with measurements in pp[over ¯] collisions at the Tevatron. By combining transverse-momentum (p_{T}) distributions of b quarks from perturbative QCD with thermal weights and independent fragmentation toward high p_{T}, a fair description of the p_{T}-dependent B[over ¯]_{s}^{0}/B^{-} and Λ_{b}^{0}/B^{-} ratios measured in pp collisions at the LHC is obtained. The observed enhancement of Λ_{b}^{0} production is attributed to the feeddown from thus far unobserved excited b baryons. Finally, we implement the hadrochemistry into a strongly coupled transport approach for b quarks in heavy-ion collisions, utilizing previously determined b-quark transport coefficients in the quark-gluon plasma, to highlight the modifications of hadrochemistry and collective behavior of b hadrons in Pb-Pb collisions at the LHC.

Piano Soundboard Analysis at Radiated Sound

The piano is a complex musical instrument consisting of several components influencing vibration and sound production. By understanding the sound production mechanism virtual instruments can be created (physics-based sound synthesis) and the design and manufacturing of soundboards can be supported (virtual prototyping). Based on previous results published in the literature, a piano model was built and extended by a near field sound radiation model capable for physics-based sound synthesis. In this paper a simplified piano model is presented, including hammer strike and hysteretic felt models, coupled lossy string model and a 2D FEM based stiffened plate model for soundboard. This paper contains a parametric study where the soundboard parameters, such as its material characteristics and boundary conditions, are modified and their effect on the soundboard's modal behavior and the radiated sound is analyzed. Instead of using only musical (qualitative) descriptors, e.g. brightness or coloring, the piano sounds are characterized based on standard quantitative descriptors (e.g. harmonic ratio, spectral centroid). It is shown that these descriptors are determined by soundboard admittance, string characteristics and position on the soundboard; radiated sound from wooden soundboards can be characterized as harmonic for wide range of initial material descriptors; the string position is essential, and the perceived sound can differ significantly for different listening positions, even for the same harmonic decay pattern.

Warmer temperature promotes the contribution of invertebrate fauna to litter components release in an alpine meadow on the Qinghai-Tibetan Plateau

How warming and invertebrate fauna concurrently influence litter carbon and nutrient turnover in alpine meadow is still poorly known. Using a litterbag technique, we evaluated the effects of temperature (ambient temperature vs. warming temperature) × mesh (fine mesh without invertebrate fauna access vs. coarse mesh with invertebrate fauna access) on litter decay (i.e., carbon and nitrogen release, lignin and cellulose degradation) across two typical seasons (cold season vs. warm season) in an alpine meadow ecosystem on the Qinghai-Tibetan Plateau. Our results showed that the whole-soil-profile warming significantly increased litter cellulose degradation (+47%), but less affected the decay of other litter components (i.e., carbon, nitrogen, and lignin: + 7–18% increase). The loss of nitrogen and lignin from litter significantly increased by ca. 2 times in the presence of invertebrate fauna. Moreover, the release of all litter chemical components was significantly faster (by 1.5–5.2 times) in warm season than in cold season. Further, litter carbon release and lignin degradation rates were markedly influenced by the interacting effects of mesh × season, and mesh × temperature, respectively. Overall, these findings highlight the importance of invertebrate fauna as a commonly overlooked co-determinant of the warming effect on litter decay patterns in cold biomes; the changed release rates of litter components in the context of on-going warming may have far-reaching effects on carbon and nutrient cycling in alpine ecosystems.

Long-Range Social Influence in Phone Communication Networks on Offline Adoption Decisions

We use high-resolution mobile phone data with geolocation information and propose a novel technical framework to study how social influence propagates within a phone communication network and affects the offline decision to attend a performance event. Our fine-grained data are based on the universe of phone calls made in a European country between January and July 2016. We isolate social influence from observed and latent homophily by taking advantage of the rich spatial-temporal information and the social interactions available from the longitudinal behavioral data. We find that influence stemming from phone communication is significant and persists up to four degrees of separation in the communication network. Building on this finding, we introduce a new “influence” centrality measure that captures the empirical pattern of influence decay over successive connections. A validation test shows that the average influence centrality of the adopters at the beginning of each observational period can strongly predict the number of eventual adopters and has a stronger predictive power than other prevailing centrality measures. Our centrality measure can be used to improve optimal seeding strategies in contexts with influence over phone calls, such as targeted or viral marketing campaigns.

Intraoperative glioma characterization using time-resolved fluorescence spectroscopy.

2072 Background: Extent of surgical resection significantly improves progression-free and overall survival in glioma patients. Due to the infiltrative nature of gliomas, tumor margin detection is often difficult, and current intraoperative visualization methods are limited. Time-resolved fluorescence spectroscopy (TRFS) has the potential of differentiating glioma from normal brain tissue, thereby maximizing extent and safety of resection. Methods: Twenty-seven preoperative patients diagnosed with glioma met inclusion criteria for an IRB-approved study aimed to assess the accuracy of TRFS relative to tissue histopathology for differentiating glioma from normal cortex (NC), normal white matter (NWM), and white matter with edema (WME). A multi-channel TRFS system was developed for in vivo brain tissue and tumor characterization during glioma surgery. A custom-designed fiber optic probe was used to deliver ultrafast laser pulses to tissue regions of interest and collect fluorescence signals, with simultaneous registration to intraoperative neuronavigation. The fluorescence light was collected using a photomultiplier tube and digitized across six wavelength bands. Biopsies were taken at each measurement site for evaluation by a blinded neuropathologist to determine the accuracy of TRFS, which was calculated using parameters derived from the recorded fluorescence pulse and used to characterize tissue signatures. Results: During surgical resection of 27 patients, 162TRFS measurements were collected in vivo followed by biopsy of the same tissue. Samples from brain tumors (39 low grade gliomas (LGG, WHO grade I to III), 35 high grade gliomas (HGG, WHO grade IV)) were compared with 47 samples of normal brain tissue (NC and NWM). The time-resolved system was able to differentiate LGG from normal tissue with 97% sensitivity and 93% specificity (93% PPV and 98% NPV). When all tumor grades were tested, the sensitivity dropped to 91% (96% PPV and 86% NPV), which we believe reflects the heterogeneity of HGG. HGG alone showed a sensitivity of 83% and specificity of 93% (91% PPV and 88% NPV). Normal cortex had the fastest decays across all wavelength bands among different tissue types, WME had longer decays compared to other tissue types at all wavelengths, and HGG had a variable but predictably different fluorescence decay pattern. Conclusions: TRFS is an intraoperative tool that can distinguish glioma from normal brain tissue and has the potential to maximize safe surgical resection.

The structure of microbial communities in redoximorphic microsites of Gleysol

AbstractMicrobial communities were studied in redoximorphic microsites of highly heterogeneous Gleysol at a mm scale using 16S and 18S amplicon sequencing to demonstrate if the composition of soil microbes reflects the differences in ferric and ferrous micro‐sites. In both explored gley horizons with redoximorphic features (Bg2 and Cg), ferric mottles were significantly enriched with total P and Fe and depleted of O, Si, Al, K and Ca compared with the adjacent ferrous groundmass (SEM–EDS). Ferric mottles were determined as Fe oxide coatings and hypocoatings. In Bg2, both prokaryotic and micro‐eukaryotic communities differed significantly between mottles and groundmass in composition of operational taxonomic units (OTUs) and in proportions of phyla, reflecting heterogeneities in the soil properties there. Mottles in Bg2 were characterized by increased proportion of Proteobacteria, decreased proportion of Acidobacteriota among prokaryotes and by dominance of a single proteobacterial OTU from Anaplasmataceae compared to all other samples. The composition of micro‐eukaryotes showed an opposite trend, as micro‐eukaryotes of Bg2 groundmass were unique among the other horizons, while micro‐eukaryotes of Bg2 mottles had similar composition to neighbouring horizons. Microbial communities of adjacent samples were not more similar to each other than communities of randomly selected ones in Bg2 horizon. That suggests that at mm scale, the sample distance does not represent the driving factor of microbial community composition and that the adjacent samples differ rather due to physicochemical factors. The spatial organization of microbial communities revealed in Bg2 has not reappeared in similarly organized Cg horizon, probably due to other overriding factors. The differences revealed between Bg2 and Cg horizons, including granulometric composition, content of crystalline Fe, exchangeable Al, and organic carbon, as well as exposition to groundwater, were discussed as possible reasons of the distinct organization in Cg. The similarity of pro−/eukaryotic communities of adjacent and non‐adjacent couples suggests no distance decay pattern at a mm scale. The agreement between patchiness in soil properties and microbial communities was revealed for the first time and confirms the importance of microscale patterns in soil.

Assembly processes of eukaryotic plankton communities in the world's largest drinking water diversion project

The largest engineered water diversion project–the Middle Route of the South to North Water Diversion Project (MRP), is of strategic importance in solving the problem of the northern water shortage in China. Eukaryotic plankton are important to the water quality stability in the MRP, but little has been reported about their dynamics and assembly processes, especially for abundant and rare communities. In this study, amplicon sequencing was used to investigate the eukaryotic plankton communities. The results revealed both abundant and rare communities exhibited similar distance–decay patterns, but abundant communities were particularly subject to environmental heterogeneity and played an important role in determining seasonal differences in eukaryotic plankton communities and alpha diversity. In the MRP, with its strong hydrodynamic exchange, abundant and rare communities were mainly affected by stochastic processes, especially homogenizing dispersal. In addition, abundant communities were subject to moderate variable selection (25 %) and rare communities were affected by a higher proportion of dispersal limitation (27 % vs. 10 %). The variation in water temperature and water velocity led to a shift from a stochastic to a deterministic process dominating the assembly of abundant communities. This study extends insights into the dynamics and assembly processes of abundant and rare eukaryotic plankton communities in the large, engineered drinking water diversion project, which is also useful for the management and regulation of the MRP.

Ancient Basidiomycota in an extinct conifer-like tree, Xenoxylon utahense, and a brief survey of fungi in the Upper Jurassic Morrison Formation, USA

AbstractAlthough the well-known Upper Jurassic Morrison Formation has yielded abundant fossil plants for nearly a century, relatively little is known about fossil fungi and their ecological relationships to the Morrison flora. The first mention of fungal decay in fossil wood was briefly made over three decades ago, and since then, a few more reports of fungal decay associated with Morrison plants have been published. However, up to now, detailed data on the fossil fungi themselves have not been given from the Morrison Formation. Here we describe in detail well-preserved fossil mycelia in a silicified log of Xenoxylon utahense Xie et Gee, 2021 from the Upper Jurassic Morrison Formation at Miners Draw, Blue Mountain, near Vernal in northeastern Utah, USA. The fungal hyphae are variable in form, ranging from straight to slightly curved to highly coiled to tubular; they measure ~1.53 μm in diameter and possess clamp connections, septa, and occasional bifurcations. The occurrence of clamp connections typical of living Basidiomycota indicates a taxonomic affinity to this division of fungi. On the basis of the patterns of wood decay in the Xenoxylon log, the fossil fungi are interpreted here as pertaining to saprotrophic, white-rot wood fungi. These fossil mycelia represent a new record of ancient Basidiomycota from the Upper Jurassic Morrison Formation and provide further evidence for plant–fungus interactions in Jurassic terrestrial ecosystems.