Search

Epiphytic bryophytes are important components of forest ecosystems and play important roles in maintaining biodiversity and ecosystem function. However, the main factors driving epiphytic bryophyte diversity remain unclear. We collected the tree epiphytic bryophytes from a one-hectare plot within a temperate deciduous broadleaf forest (China). Canonical correspondence analyses and Mantel tests were used to establish linear regression models and thus dissect the effects of environmental variables (topography, light and bark physicochemical properties) on the species diversity, functional diversity, and phylogenetic diversity of epiphytic bryophytes. The relationship between environmental variables and epiphytic bryophyte diversity was analyzed using piecewise structural equation modeling. Results showed that the physicochemical properties of the bark directly influenced the species diversity and phylogenetic diversity of the epiphytic bryophytes. The physical and chemical properties of bark also indirectly affected the functional diversity of the epiphytic bryophytes. Elucidation of the factors driving epiphytic bryophyte diversity provides insights into their conservation. [ABSTRACT FROM AUTHOR]

Amphiphilic molecules such as cetyl trimethylammonium bromide (CTAB) and minerals such as graphene oxide (GO) self-assemble to form lyotropic liquid crystal (LLC) systems in water. Here we describe the preparation, structures and mechanical properties of the hybrid CTAB and GO LLC system. We present a series of phase diagrams for the CTAB/GO/water ternary system with independently varying CTAB and GO loadings, covering various combinations of the isotropic and the different lyotropic phases of each that occur as a function of concentration and temperature. The corresponding LLC microstructures are identified through polarised optical microscopy (POM) in a confined environment. We find that GO either promotes or suppresses the formation of the different LLC phases of CTAB depending on the concentration of GO and whether the GO itself is in its isotropic or lyotropic phase, resulting in the formation of a complex hybrid system. GO also significantly depresses the melting point of CTAB at moderate loadings, but the melting point recovers for higher GO loading. Rheology of the CTAB/GO/water system reveals a reinforcement effect of the GO sheets through the formation of CTAB/GO complexes that alter the hexagonal phase nanostructure. Our work reveals the diverse effects on molecular LC phases by an interpenetrating mineral LC phase, and the potential to design a wide range of novel nanostructured hybrid LLC materials. Image 1 [ABSTRACT FROM AUTHOR]

• Electrodynamic vortex ring effect can shape core-shell graphene oxide hydrogel particles. • There shapes can be produced – sphere, donut and jellyfish. • The shapes are controlled by 3 process parameters – the GO concentration, the CTAB concentration and the impact velocity. • The shapes are determined by 3 dimensionless parameters – the Reynolds, Weber and Ohnesorge numbers. • The particles can be used for highly efficient adsorptive purification of water. The vortex ring (VR) effect occurs when fluid droplets impact on another fluid, leading to toroidal flow within the impacting droplet due to viscous friction, resulting in a wide variety of flow-induced morphologies. When applied to dispersions of 2-dimensional materials, such as graphene oxide (GO) in water, the VR effect can be used to generate 3-dimensional assemblies of GO flakes. Here, we have taken advantage of the surface charge on GO flakes in water, interacting with cationic aqueous surfactant systems, to generate an electrohydrodynamic VR effect. This yields GO hydrogel and aerogel microparticles with complex axially symmetric shapes, with a core-shell structure featuring a shell of aligned GO flakes. Using high frame-rate optical imaging, we have captured the real-time self-assembly of GO core-shell hydrogel microparticles shaped like spheres, donuts and jellyfish. We describe, both qualitatively and quantitatively, the electrohydrodynamics that drive the formation of such shapes. We also demonstrate how the underlying processes can be tuned by varying parameters such as GO concentration, flake size and drop velocity, and surfactant chemistry and concentration to produce a wide variety of controllable exterior and interior morphologies. Indeed, we show that the formation regimes of the different shapes are determined by dimensionless Weber and Ohnesorge numbers. Lastly, we demonstrate how these microparticles can be used for the efficient adsorption and removal of anionic contaminants in water, with tuneable adsorption capacity. [ABSTRACT FROM AUTHOR]

The cliff fern family Woodsiaceae has experienced frequent taxonomic changes at the familial and generic ranks since its establishment. The bulk of its species were placed in Woodsia, while Cheilanthopsis, Hymenocystis, Physematium, and Protowoodsia are segregates recognized by some authors. Phylogenetic relationships among the genera of Woodsiaceae remain unclear because of the extreme morphological diversity and inadequate taxon sampling in phylogenetic studies to date. In this study, we carry out comprehensive phylogenetic analyses of Woodsiaceae using molecular evidence from four chloroplast DNA markers (atpA, matK, rbcL and trnL–F) and covering over half the currently recognized species. Our results show three main clades in Woodsiaceae corresponding to Physematium (clade I), Cheilanthopsis–Protowoodsia (clade II) and Woodsia s.s. (clade III). In the interest of preserving monophyly and taxonomic stability, a broadly defined Woodsia including the other segregates is proposed, which is characterized by the distinctive indument and inferior indusia. Therefore, we present a new subgeneric classification of the redefined Woodsia based on phylogenetic and ancestral state reconstructions to better reflect the morphological variation, geographic distribution pattern, and evolutionary history of the genus. Our analyses of the cytological character evolution support multiple aneuploidy events that have resulted in the reduction of chromosome base number from 41 to 33, 37, 38, 39 and 40 during the evolutionary history of the cliff ferns. [ABSTRACT FROM AUTHOR]

Traffic flow prediction is crucial for intelligent transportation system, such as traffic management, congestion alleviation and public risk assessment. Recently, attention mechanism and deep neural networks are utilized to capture traffic dependencies. However, two challenges have yet to be well addressed: (i) previous works overlook the global dependencies across different regions; (ii) how to integrate spatial and temporal information aggregation with latent channel-aware semantics. To tackle these issues, we propose a deep spatial–temporal convolutional graph attention network for citywide traffic flow prediction. We first apply the multi-resolution transformer network to capture traffic dependencies among different regions with the encoding of multi-level periodicity. Spatial dependencies are captured by the attentive graph neural networks followed by convolutional networks from local view to global view. We further propose to inject spatial contextual signals into our framework with the designed channel-aware recalibration residual network, which effectively endows model with the capability of mapping spatial–temporal data patterns into different representation subspaces of latent semantics. The extensive experiments on four real-world datasets demonstrate at least 5% performance gain of our framework by comparing with 19 state-of-the-art traffic prediction methods. [ABSTRACT FROM AUTHOR]

Lindera obtusiloba Blume is the northernmost tree species in the family Lauraceae, and it is a key species in understanding the evolutionary history of this family. The species of L. obtusiloba in East Asia has diverged into the Northern and Southern populations, which are geographically separated by an arid belt. Though the morphological differences between populations have been observed and well documented, intraspecific variations at the plastomic level have not been systematically investigated to date. Here, ten chloroplast genomes of L. obtusiloba individuals were sequenced and analyzed along with three publicly available plastomes. Comparative plastomic analysis suggests that both the Northern and the Southern populations share similar overall structure, gene order, and GC content in their plastomes although the size of the plasome and the level of intraspecific variability do vary between the two populations. The Northern have relatively larger plastomes while the Southern population possesses higher intraspecific variability, which could be attributed to the complexity of the geological environments in the South. Phylogenomic analyses also support the split of the Northern and Southern clades among L. obtusiloba individuals. However, there is no obvious species boundary between var. obtusiloba and var. heterophylla in the Southern population, indicating that gene flow could still occur between these two varieties, and this could be used as a good example of reticulate evolution. It is also found that a few photosynthesis‐related genes are under positive selection, which is mainly related to the geological and environmental differences between the Northern and the Southern regions. Our results provide a reference for phylogenetic analysis within species and suggest that phylogenomic analyses with a sufficient number of nuclear and chloroplast genomic target loci from widely distributed individuals could provide a deeper understanding of the population evolution of the widespread species. [ABSTRACT FROM AUTHOR]

Soil degradation of urban greening has caused soil fertility loss and soil organic carbon depletion. Organic mulches are made from natural origin materials, and represent a cost-effective and environment-friendly remediation method for urban greening. To reveal the effects of organic mulch on soil physicochemical characteristics and fertility, we selected a site that was covered with organic mulch for 6 years and a nearby lawn-covered site. The results showed that soil organic matter, total nitrogen, and available phosphorus levels were improved, especially at a depth of 0–20 cm. The activities of cellulase, invertase, and dehydrogenase in soil covered with organic mulch were 17.46%, 78.98%, and 283.19% higher than those under lawn, respectively. The marker genes of fermentation, aerobic respiration, methanogenesis, and methane oxidation were also enriched in the soil under organic mulch. Nitrogen cycling was generally repressed by the organic mulch, but the assimilatory nitrate and nitrite reduction processes were enhanced. The activity of alkaline phosphatase was 12.63% higher in the mulch-covered soil, and functional genes involved in phosphorus cycling were also enriched. This study presents a comprehensive investigation of the influence of organic mulch on soil microbes and provides a deeper insight into the recovery strategy for soil degradation following urban greening. Key points: • Long-term cover with organic mulches assists soil recovery from degradation • Soil physical and chemical properties were changed by organic mulches • Organic mulches enhanced genes involved in microbially mediated C and P cycling • Soil organic matter was derived from decomposition of organic mulch and carbon fixation • N cycling was repressed by mulches, except for assimilatory NO2− and NO3− reductions [ABSTRACT FROM AUTHOR]

Urbanization induces rapid plant environmental modifications, leading to alterations in plant diversity distribution patterns and plant homogenization. However, how plant diversity is distributed along urbanization gradients in regional urban agglomerations and its relationship with environmental factors are not well defined. In three nearby Henan Province Chinese cities—Zhengzhou, Kaifeng, and Zhongmu—along an urbanization gradient, the distribution pattern of plant diversity was quantified. Both native and non-native plants found in urban green spaces were taken into consideration. A total of 176 plant quadrats were selected and separated into three urbanization gradient types using space-constrained hierarchical clustering: urban core, urban suburb, and urban outskirt. Polynomial fitting was used to characterize the spatial distribution patterns of plants along the urbanization gradient, and Pearson correlation and the Mantel test were employed to examine the effects of environmental factors, including longitude, latitude, altitude, distance from the urban center, temperature, and illumination, on plant diversity. A total of 313 vascular plant species, comprising 137 woody species and 176 herbaceous species, were examined. Along the three urbanization gradients, remarkable variations in plant diversity for woody and herbaceous species were observed. The spatial patterns of plant diversity were consistent across cities, whereas woody plants and herbaceous plants displayed the opposite behavior. Distance to the city center and temperature were the most substantial environmental effect factors for the diversity of woody plants, whereas light factors had a major impact on herbaceous plants. These findings show different life-type plants are affected differently by urbanization, and they offer managers and planners a recommendation for increasing urban plant diversity by executing various interventions throughout the urban gradient. [ABSTRACT FROM AUTHOR]

Soil degradation of urban greening has caused soil fertility loss and soil organic carbon depletion. Organic mulches are made from natural origin materials, and represent a cost-effective and environment-friendly remediation method for urban greening. To reveal the effects of organic mulch on soil physicochemical characteristics and fertility, we selected a site that was covered with organic mulch for 6 years and a nearby lawn-covered site. The results showed that soil organic matter, total nitrogen, and available phosphorus levels were improved, especially at a depth of 0–20 cm. The activities of cellulase, invertase, and dehydrogenase in soil covered with organic mulch were 17.46%, 78.98%, and 283.19% higher than those under lawn, respectively. The marker genes of fermentation, aerobic respiration, methanogenesis, and methane oxidation were also enriched in the soil under organic mulch. Nitrogen cycling was generally repressed by the organic mulch, but the assimilatory nitrate and nitrite reduction processes were enhanced. The activity of alkaline phosphatase was 12.63% higher in the mulch-covered soil, and functional genes involved in phosphorus cycling were also enriched. This study presents a comprehensive investigation of the influence of organic mulch on soil microbes and provides a deeper insight into the recovery strategy for soil degradation following urban greening. Key points: • Long-term cover with organic mulches assists soil recovery from degradation • Soil physical and chemical properties were changed by organic mulches • Organic mulches enhanced genes involved in microbially mediated C and P cycling • Soil organic matter was derived from decomposition of organic mulch and carbon fixation • N cycling was repressed by mulches, except for assimilatory NO2− and NO3− reductions [ABSTRACT FROM AUTHOR]

[Display omitted] Electromagnetic wave absorbers constructed by reduced graphene oxide (rGO) and magnetic nanoparticles are extremely desirable for enhancing electromagnetic wave absorption performance due to the effective integration of the properties of dielectric and magnetic materials. However, the arrangement of graphene sheets and the growth of magnetic nanoparticles have always been challenging. Herein, an in-situ growth process has been used to successfully prepare accordion-like graphene with homogeneously distributed Fe nanoparticles in the confined structure via ion absorption and pyrolysis. The as-prepared Fe/layered rGO composites show excellent electromagnetic wave absorption performance with thin thickness, low filler loading, and broad effective absorption bandwidth (EAB). The minimum reflection loss of the composites achieves −54.6 dB with 20 wt% filler loading, and the tunable EAB reach 6.8 GHz (2.2 mm with 10 wt% filler loading) and 4.6 GHz (2.8 mm with 30 wt% filler loading), which can cover the entire Ku-band and X-band. The mechanism analysis indicates that the superior absorption performance is attributed to the multi-component loss mechanism, enhanced impedance matching degree and attenuation ability caused by the synergistic effect of layered rGO sheets and magnetic nanoparticles. This work opens up a new avenue for constructing accordion-like graphene-based composites as highly efficient electromagnetic wave absorbers. [ABSTRACT FROM AUTHOR]

[Display omitted] Electromagnetic wave absorbers constructed by reduced graphene oxide (rGO) and magnetic nanoparticles are extremely desirable for enhancing electromagnetic wave absorption performance due to the effective integration of the properties of dielectric and magnetic materials. However, the arrangement of graphene sheets and the growth of magnetic nanoparticles have always been challenging. Herein, an in-situ growth process has been used to successfully prepare accordion-like graphene with homogeneously distributed Fe nanoparticles in the confined structure via ion absorption and pyrolysis. The as-prepared Fe/layered rGO composites show excellent electromagnetic wave absorption performance with thin thickness, low filler loading, and broad effective absorption bandwidth (EAB). The minimum reflection loss of the composites achieves −54.6 dB with 20 wt% filler loading, and the tunable EAB reach 6.8 GHz (2.2 mm with 10 wt% filler loading) and 4.6 GHz (2.8 mm with 30 wt% filler loading), which can cover the entire Ku-band and X-band. The mechanism analysis indicates that the superior absorption performance is attributed to the multi-component loss mechanism, enhanced impedance matching degree and attenuation ability caused by the synergistic effect of layered rGO sheets and magnetic nanoparticles. This work opens up a new avenue for constructing accordion-like graphene-based composites as highly efficient electromagnetic wave absorbers. [ABSTRACT FROM AUTHOR]

Background: Soil microbiome is an important part of the forest ecosystem and participates in forest ecological restoration and reconstruction. Niche differentiation with respect to resources is a prominent hypothesis to account for the maintenance of species diversity in forest ecosystems. Resource-based niche differentiation has driven ecological specialization. Plants influence soil microbial diversity and distribution by affecting the soil environment. However, with the change in plant population type, whether the distribution of soil microbes is random or follows an ecologically specialized manner remains to be further studied. We characterized the soil microbiome (bacteria and fungi) in different plant populations to assess the effects of phytophysiognomy on the distribution patterns of soil microbial communities in a temperate forest in China. Results: Our results showed that the distribution of most soil microbes in different types of plant populations is not random but specialized in these temperate forests. The distribution patterns of bacteria and fungi were related to the composition of plant communities. Fungal species (32%) showed higher specialization than bacterial species (15%) for different types of plant populations. Light was the main driving factor of the fungal community, and soil physicochemical factors were the main driving factor of the bacterial community. Conclusion: These findings suggest that ecological specialization is important in maintaining local diversity in soil microbial communities in this forest. Fungi are more specialized than bacteria in the face of changes in plant population types. Changes in plant community composition could have important effects on soil microbial communities by potentially influencing the stability and stress resistance of forest ecosystems. [ABSTRACT FROM AUTHOR]

A serial oxygen vacancy (OV) on Nb2O5 is synthesised by H2 calcination, and H-300 exhibited high selectivity and activity for H2O2 (93.4%, 562.5 mmol gcat−1). A volcano relationship is identified between the OV content and performance, which provides an attractive insight into designing electrocatalysts. [ABSTRACT FROM AUTHOR]

Modern integrated electronics are in great demand for high-performance electromagnetic interference (EMI) shielding materials with exceptional mechanical properties. Liquid metal (LM) has demonstrated great potential in EMI shielding by its superior electrical conductivity. However, its real-world EMI application is limited by the poor compatibility, insulating oxide shells, and unpredictable leakage. Here, graphene oxide (GO) is used to encapsulate LM to form LM@GO microdroplets dispersion, and bacterial cellulose (BC) is applied to construct a biocompatible fabric network. Moreover, GO is in-situ reduced by hydrazine vapor, which generates synergistic LM/reduced graphene oxide (rGO) conductive pathways with the aid of roll-in process, obtaining flexible LM/rGO/BC (LGB) composite film with outstanding electrical conductivity of 4.5 × 104 S/m and exceptional shielding effectiveness of 64.0 dB. The rGO sheets and BC network demonstrate layered structure after roll-in process, effectively impeding the leakage and oxidation of LM and achieving a tensile strength up to 62.9 MPa of LGB films. Meanwhile, the LGB films exhibit exceptional Joule heating performance, and the stable surface temperature reaches 110 °C with high stability and reliability when the applied voltage is 4 V. This work provides a feasible engineering approach to prepare LM-based films for applications in EMI shielding and wearable electronics. [Display omitted] [ABSTRACT FROM AUTHOR]

Humus layer has an important effect on the diversity and spatial distribution of microbes. However, the role of partitioning of humus layer microhabitats for soil microbial diversity has been poorly documented. In this study, 120 soil samples were collected from a 5‐ha forest dynamic monitoring sample plot in a deciduous broad‐leaved forest. Clustering analysis was used to delineate microhabitats by humus layer. We explored diversity and community composition of soil fungi and bacteria using Illumina sequencing of the ITS rRNA gene and 16S rRNA gene region on the MiSeq platform. We investigated the diversity, species composition, and the microhabitat preferences of fungi and bacteria and then analyzed the effects of environmental factors on soil fungi and bacteria. Our results showed that the diversity, species composition, and the indicator species of the fungal and bacterial community varied among different humus layer microhabitats. In network analysis, the specialization indexes showed that 16.20%/22.30% of the fungal/bacterial operational taxonomic units (OTUs) had the characteristics of distribution specialization for humus layer microhabitats. Mantel test showed that the main environmental drivers of fungi and bacteria were not consistent among the four microhabitats. Our findings indicated that the distribution of soil microbes among humus layer microhabitats is not random, but specialized. We furthermore found that there were differences in the relationship between soil microbes and environment among microhabitats defined by humus layer. Together, these findings suggest the importance of partitioning of humus layer microhabitats in maintaining local diversity in a soil microbial community. [ABSTRACT FROM AUTHOR]

• New CNN design with complex-valued operations. • Practical complex-valued CNN for image denoising. • Proposed CNN is effective for handling unseen noises. • State-of-the-art results are achieved. While complex-valued transforms have been widely used in image processing and have their deep connections to biological vision systems, complex-valued convolutional neural networks (CNNs) have not seen their applications in image recovery. This paper aims at investigating the potentials of complex-valued CNNs for image denoising. A CNN is developed for image denoising with its key mathematical operations defined in the complex number field to exploit the merits of complex-valued operations, including the compactness of convolution given by the tensor product of 1D complex-valued filters, the nonlinear activation on phase, and the noise robustness of residual blocks. The experimental results show that, the proposed complex-valued denoising CNN performs competitively against existing state-of-the-art real-valued denoising CNNs, with better robustness to possible inconsistencies of noise models between training samples and test images. The results also suggest that complex-valued CNNs provide another promising deep-learning-based approach to image denoising and other image recovery tasks. [ABSTRACT FROM AUTHOR]

Electrochemical oxygen reduction reaction (ORR) through a two-electron pathway has been provided a green route for on-site hydrogen peroxide (H 2 O 2) production. Developing high-selective electrocatalysts for H 2 O 2 production are urgently sought. Herein, a m-Bi 2 O 3 /Ta 2 O 5 electrocatalyst (m: "Bi" mass contents) has been successfully synthesized by simple physical mixing associated with an outstanding selectivity towards H 2 O 2 (94.7%), over 10% higher than Ta 2 O 5 (80.9%) and Bi 2 O 3 (81.7%). 10-Bi 2 O 3 /Ta 2 O 5 also exhibits 471 mmol/(g cat ·h) H 2 O 2 yield with 91.8% Faraday Efficiency. The in-situ generated H 2 O 2 can function as disinfection agent for efficiently deactivating model bacteria (e.g., Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli) within 30 min. In-situ Raman and DFT proposed the synergistic effects of Bi 2 O 3 and Ta 2 O 5 in boosting 2e- ORR performance. In this work, it not only presents a high-selective electrocatalyst for 2e- ORR, but also provides a new idea for electrocatalyst design from the perspective of reaction process. [Display omitted] • Electrocatalytic H2O2 production of 10-Bi2O3/Ta2O5 reaches a 94.7% high selectivity. • Enhanced O2 adsorption and H2O dissociation of 10-Bi2O3/Ta2O5 results in efficient OOH formation. • 10-Bi2O3/Ta2O5 exhibits excellent durability for 80 h at 0.4 VRHE. • Over 90% FE during H2O2 produce in homemade H-cell. • The applications of on-site production of low-concentration H2O2 in water disinfection. [ABSTRACT FROM AUTHOR]

• A Pd/Ni(OH) 2 -NF catalyst was prepared for deuteration (hydrogenation) reaction of aryl alkynes. • A room-temperature one-pot two-step transformation of 4-ethynylaniline to deuterated 4-vinylanilin was constructed with a conversion rate of up to 96%, a selectivity of 98%, and a deuterium ratio of 99% using D 2 O as a deuterium source. • The rapid kinetics of D 2 O electrolysis was proved to contribute to the semi-deuteration of aryl alkynes by electrochemical analysis. • A wide range of substrates and easy access to hydrogenated alkenes highlight the promising applications. The preparation of deuterated alkenes via electrochemistry from a readily available deuterated source has the advantages of mild reaction conditions, sustainability, and cost-effectiveness. Hydrogen isotopic exchange is a simple method to introduce deuterium atoms into molecules without prior functionalization. However, this process typically requires complex ligand catalysts, costly sources of deuterium, and strong bases and acids to activate the robust C-H bonds. The deuterated incorporation sites and their corresponding numbers are difficult to control. In this study, an in-situ electrochemical deuteration system is reported that is based on a Pd/Ni(OH) 2 nanoflake catalyst grown on a commercial nickel foam conductive substrate was used as the cathodic working electrode. A room-temperature, one-pot, two-step transformation of 4-ethynylaniline to deuterated 4-vinylanilin was achieved with a conversion rate of up to 96%, selectivity of 98%, and a deuterium ratio of 99% using D 2 O as the deuterium source. The interaction between Pd and Ni(OH) 2 -NF promoted the rapid cleavage of D 2 O during the semi-deuteration of aryl alkynes. The key deuterium and carbon radical intermediates were confirmed using electron paramagnetic resonance spectroscopy. A wide range of substrates and easy access to hydrogenated alkenes highlight the promising applications. [ABSTRACT FROM AUTHOR]