Trivalent Phosphine-Catalyzed [4+1] Spiro-annulation Reaction Using Allenyl Imide and Methylene Cyclocompounds.

The trivalent phosphine-catalyzed [4+1] spiro-annulation reaction of allenyl imide and activated methylene cyclocompounds has been developed for the construction of various spiro-2-cyclopenten-1-ones. Oxindoles, 3-isochromanones, and 2-indanones are selected as 1C synthons to capture the in situ-generated bis-electrophilic α,ß-unsaturated ketenyl phosphonium intermediate, affording the corresponding monospiro- and bispiro-cyclopentenones in good to excellent yields (≤91%) under mild conditions. The primary attempt at asymmetric catalysis using monophosphine (R)-SITCP provides promising enantioselectivity (45% ee). A plausible reaction mechanism is also proposed.

Chromosome-level genome assembly defines female-biased genes associated with sex determination and differentiation in the human blood fluke Schistosoma japonicum.

Schistosomiasis is a neglected tropical disease of humans caused by blood flukes of the genus Schistosoma, the only dioecious parasitic flatworm. Although aspects of sex determination, differentiation and reproduction have been studied in some Schistosoma species, almost nothing is known for Schistosoma japonicum, the causative agent of schistosomiasis japonica. This mainly reflects the lack of high-quality genomic and transcriptomic resources for this species. As current genomes for S. japonicum are highly fragmented, we assembled and report a chromosome-level reference genome (seven autosomes, the Z-chromosome and partial W-chromosome), achieving a substantially enhanced gene annotation. Utilizing this genome, we discovered that the sex chromosomes of S. japonicum and its congener S. mansoni independently suppressed recombination during evolution, forming five and two evolutionary strata, respectively. By exploring the W-chromosome and sex-specific transcriptomes, we identified 35 W-linked genes and 257 female-preferentially transcribed genes (FTGs) from our chromosomal assembly and uncovered a signature for sex determination and differentiation in S. japonicum. These FTGs clustering within autosomes or the Z-chromosome exhibit a highly dynamic transcription profile during the pairing of female and male schistosomula, thereby representing a critical phase for the maturation of the female worms and suggesting distinct layers of regulatory control of gene transcription at this development stage. Collectively, these data provide a valuable resource for further functional genomic characterization of S. japonicum, shed light on the evolution of sex chromosomes in this highly virulent human blood fluke, and provide a pathway to identify novel targets for development of intervention tools against schistosomiasis.

Integrated Evaluation of Financial Risk in Coal Industry Restructuring: A Model of Linear Regression and PCA.

Aiming at the integrated evaluation problem of financial risk in coal industry restructuring, a model of linear regression and PCA is put forward. This paper studies the univariate correlation and multivariable mixed correlation between the main business income and the book value of fixed assets and nonfixed assets in the statements of coal listed companies and gives the correlation function between the variables by using a variety of univariate linear, univariate nonlinear, and binary linear regression methods. It also points out that the coal enterprises in China are basically in the stage of increasing scale income at the present stage and can continue to achieve rapid increase in profits through mergers and acquisitions and other expansion methods. At the same time, it is also concluded that nonfixed assets, namely, intangible assets and human capital, contribute more to the main business income of coal enterprises in China, which objectively proves the correctness of our thinking of developing knowledge economy.

Water flow and temperature drove epiphytic microbial community shift: Insight into nutrient removal in constructed wetlands from microbial assemblage and co-occurrence patterns.

The impacts of water flow and low temperature on nutrient removal and underlying ecological mechanism of epiphytic microbial community in constructed wetlands remain to be fully illustrated. In this study, low temperature inhibited the decrease of TN, NH4+-N, TP, and COD concentrations in water, but water flow decreased NH4+-N and COD concentrations strikingly. The relative conductivity, soluble sugar, and protein of M. spicatum increased, while the total chlorophyll contents decreased significantly under the stress of water flow and low temperature. Temperature affected the alpha-diversity and composition of the microbial community, while water flow caused differences in community distribution. Deterministic processes dominated in microbial community assembly with increasing environmental stress. Co-occurrence network analysis demonstrated that Chlorophyta, Verrucomicrobia, Proteobacteria, Bacteroidetes, and Firmicutes phyla were the dominant hubs in September, however, low temperatures caused a shift to Metazoan dominated network, demonstrating diminished nutrient removal capacity.

A novel metal-organic framework derived carbon nanoflower with effective electromagnetic microwave absorption and high-performance electrochemical energy storage properties.

Here we report on the electrochemical performance and electromagnetic microwave absorption (EMWA) properties of a novel metal-organic framework derived carbon nanomaterial. This carbon material shows high-performance electrochemical energy storage, and has a maximum reflection loss of 27.6 dB with an effective absorption bandwidth of 2.24 GHz.

Nitrate application decreased microbial biodiversity but stimulated denitrifiers in epiphytic biofilms on Ceratophyllum demersum.

Among nitrogen species, nitrate is more stable than ammonium and nitrite, and it is an important nitrogenous pollutant in surface water. However, little is known about the characterization of epiphytic microbial communities on submersed macrophytes under nitrate loading. In this study, we investigated the co-occurring pattern and response of bacteria and microeukaryotes in epiphytic biofilms under nitrate loading. Nitrate loading significantly affected bacterial and eukaryotic communities, and turnover played greater contribution to the total dissimilarity than nestedness by partitioning beta-diversity analysis. Cyanobacteria, α-proteobacteria, ß-proteobacteria, Actinobacteria, Planctomycetes, Bacteroidetes, and γ-proteobacteria were dominant bacterial phyla/classes. Metazoan (phylum Arthropoda, Rotifera, Gastrotricha, Annelida, and Nematoda) and algae (phylum Bacillariophyta, Chlorophyta, and Streptophyta) were dominated in eukaryotic communities. The abundances of denitrifying bacteria (Rhodobacter, Acinetobacter, Bacillus, Flavobacterium, and Pseudomonas) and genes (nirS, cnorB, and nosZ) increased with nitrate loading. The network analysis showed there were complex interactions among photosynthetic microbes, metazoan, and bacteria (including denitrifiers) that they were potentially interrelated via photosynthesis, predation or feeding. This study provides new perspectives into understanding the factors affecting nitrate removal mechanisms in wetlands with submersed macrophytes.

Characterization and co-occurrence of microbial community in epiphytic biofilms and surface sediments of wetlands with submersed macrophytes.

Microbes in epiphytic biofilms and surface sediments play crucial roles in the biogeochemical cycles in wetlands. However, little is known about the compositions of microbial community in wetlands dominated with submersed macrophytes. In this study, bacterial and eukaryotic community in epiphytic biofilms and surface sediments were investigated in wetlands with artificial plants and Myriophyllum verticillatum from September (~27 °C) to January (~9 °C). A total of 30 (including 13 bacterial and 17 eukaryotic) and 34 (including 14 bacterial and 20 eukaryotic) phyla were detected in epiphytic biofilms and sediments, respectively. Microbial community in epiphytic biofilms shifted with decreasing temperature, and biofilms on M. verticillatum were generally similar to those on artificial plants. Though the OTUs and Shannon values were significantly higher in sediments than epiphytic biofilms (p < 0.05), numbers of strongly correlated edges detected in biofilms (64 nodes with 182 edges) were at least three times of those in sediments (40 nodes with 57 edges) as revealed by co-occurrence networks analysis (|r| > 0.7, p < 0.05). These data suggest that there were complex interactions among microbes in epiphytic biofilms than sediments. Positive relationships among microbes revealed the predation, symbiosis, parasitism relationships and the collective degradation of organic matter, while negative ones may be ascribed to their different lifestyles. These results highlight that artificial plants play a similar role as submersed macrophytes as microbial carriers and can be potentially used an alternative substitutes to submersed macrophytes in wetlands.

Dissolved organic matter release in overlying water and bacterial community shifts in biofilm during the decomposition of Myriophyllum verticillatum.

This study investigated the alterations in biomass, nutrients and dissolved organic matter concentration in overlying water and determined the bacterial 16S rRNA gene in biofilms attached to plant residual during the decomposition of Myriophyllum verticillatum. The 55-day decomposition experimental results show that plant decay process can be well described by the exponential model, with the average decomposition rate of 0.037d-1. Total organic carbon, total nitrogen, and organic nitrogen concentrations increased significantly in overlying water during decomposition compared to control within 35d. Results from excitation emission matrix-parallel factor analysis showed humic acid-like and tyrosine acid-like substances might originate from plant degradation processes. Tyrosine acid-like substances had an obvious correlation to organic nitrogen and total nitrogen (p<0.01). Decomposition rates were positively related to pH, total organic carbon, oxidation-reduction potential and dissolved oxygen but negatively related to temperature in overlying water. Microbe densities attached to plant residues increased with decomposition process. The most dominant phylum was Bacteroidetes (>46%) at 7d, Chlorobi (20%-44%) or Proteobacteria (25%-34%) at 21d and Chlorobi (>40%) at 55d. In microbes attached to plant residues, sugar- and polysaccharides-degrading genus including Bacteroides, Blvii28, Fibrobacter, and Treponema dominated at 7d while Chlorobaculum, Rhodobacter, Methanobacterium, Thiobaca, Methanospirillum and Methanosarcina at 21d and 55d. These results gain the insight into the dissolved organic matter release and bacterial community shifts during submerged macrophytes decomposition.