Silver-Catalyzed Direct Nucleophilic Cyclization: Enantioselective De Novo Synthesis of C-C Axially Chiral 2-Arylindoles.

Atropisomeric indoles widely exist in natural products, pharmaceuticals, functional materials, and catalysts for their featured biological activities, photoelectric properties, and catalytic activities, while facile and de novo construction of this motif remains underexplored. Herein, we report a chiral silver phosphate-catalyzed direct 5-endo-dig nucleophilic cyclization of 2-alkynylanilins under mild conditions, affording various C-C axially chiral 2-arylindoles in high to excellent yields and enantioselectivities. Control experiments implied the cooperative catalysis of AgOAc and chiral phosphoric acid, wherein the former accelerated the desired transformation while the latter improved the enantioselectivity. In addition, as the first example of silver-catalyzed enantioselective de novo synthesis of C-C axially chiral indole skeletons, synthetic applications and products' thermal stability have been investigated.

Transcriptome Analysis of Beet Webworm Shows That Histone Deacetylase May Affect Diapause by Regulating Juvenile Hormone.

The beet webworm (Loxostege sticticalis L.) is an important agricultural pest and can tolerate harsh environmental conditions by entering diapause. The diapause mechanism of beet webworm is unknown. Therefore, we conducted a transcriptomic study of the process from diapause induction to diapause release in beet webworms. The results revealed 393 gene modules closely related to the diapause of beet webworm. The hub gene of the red module was the HDACI gene, which acts through histone deacetylase (HDAC) enzymes. HDAC enzyme activity was regulated by the light duration and influenced the JH content under induced beet webworm diapause conditions (12 h light:12 h dark). In addition, transcriptomic data suggested that circadian genes may not be the key genes responsible for beet webworm diapause. However, we showed that the photoperiod affects HDAC enzyme activity, and HDAC can regulate the involvement of JH in beet webworm diapause. This study provided a new module for studying insect diapause and links histone acetylation and diapause at the transcriptome level.

Tetracycline removal in granulation: Influence of extracellular polymers substances, structure, and metabolic function of microbial community.

Tetracycline is a potentially hazardous residual antibiotic detected in various sewages. High concentration (mg/L) of tetracycline is found in pharmaceutical/hospital wastewater and wastewater derived from livestock and poultry. So far, only antibiotics in µg/L level have been reported in granulation of aerobic sludge during wastewater treatment, but its effects in high concentration are rarely reported. In this study, the influence of tetracycline in high concentration (∼2 mg/L) on the formation of granular sludge, structure, and metabolic function of the microbial community during the granulation of aerobic sludge was investigated to improve the understanding of the aerobic granular sludge formation under high-level of tetracycline. The role of extracellular polymers substances (EPSs) derived from granular sludge in the granulation and tetracycline removal process was also investigated, showing that tetracycline improved the relative hydrophobicity, flocculability and protein/polysaccharide ratio of EPSs, accelerating the granulation of sludge. Succession of microbial communities occurred during the domestication of functional bacteria present in the sludge and was accompanied with regulation of metabolic function. The addition of tetracycline lead to an increase of tetracycline-degrading bacteria or antibiotic resistance genus. Those findings provide new perspectives of the influence of tetracycline on aerobic sludge granulation and the removal mechanism of tetracycline.

[Effects of community succession on plant reproductive allocation and ecological stoichiometry for two dominant species in the Hulunbuir Grassland, China]. / ç¾¤è½æ¼”æ›¿å¯¹å‘¼ä¼¦è´å°”è‰åœ°ä¸¤ç§ä¼˜åŠ¿æ¤ç‰©ç¹æ®–åˆ†é åŠç”Ÿæ€åŒ–å­¦è®¡é‡çš„å½±å“.

To explore the physiological and ecological adaptability of different dominant species during grassland community succession, we measured soil nutrients, plant biomass and C, N and P contents of two dominant species using the method of spatial sequences instead of chronosequences in the successive series of Agropyron michnoi community - A. michnoi + A. cristatam community - A. cristatam community in Hulunbuir Grassland. During the succession progress, the contents of soil total C, total C, available N and available P increased significantly. The N and P contents and N/P of leaves, stems and roots of A. michnoi and A. cristatam increased significantly, while the C/N showed opposite response. The leaf C content of A. michnoi and the C contents of leaves, stems and roots of A. cristatam significantly increased. The leaf C/P of A. michnoi and the C/P of leaves and roots of A. cristatem increased significantly, while the C/P of stems and roots of A. michnoi and the stem C/P of A. cristatem decreased significantly. In the community co-dominated by A. michnoi and A. cristatam, A. michnoi improved its interspecific competitiveness by reducing C content in stems and roots and increasing the C content in leaves, while A. cristatem adapted to environmental changes by reducing root to shoot ratio and reproductive ratio. A. michnoi was limited by N availability (N/P<14) in different communities, while A. cristatem was limited by P availability in single dominant community(N/P>16)and by both N and P in co-dominant community (14

A 2-Fold Interpenetrated Nitrogen-Rich Metal-Organic Framework for Rapid and Selective Adsorption of Congo Red.

A new metal-organic framework was prepared based on a mixed ligand system of the designed nitrogen-rich 3,6-bis(2-methylimidazole)pyrimidine (b2mpm) and benzophenone 4,4'-dicarboxylic acid (H2bpndc). The prepared material shows a three-dimensional 2-fold interpenetrated pcu framework and features rectangular channels decorated with nitrogen sites. Thanks to the abundant hydrogen bonding and π-π stacking interactions, the titled material can rapidly adsorb Congo red (CR) and presents ultrahigh adsorption capacity (2348 mg g-1). Moreover, this material has an adsorptive selectivity toward CR and can be regenerated by simply washing it with ethanol. The adsorption kinetic and isotherm of the titled material were also determined, indicating that the adsorption kinetic conforms to the pseudo-second-order model and the adsorption isotherm obeys the Langmuir model. Additionally, the titled material exhibits the suitable adsorption ability toward CO2 (15.2 cm3 g-1 under 1 atm at 298 K). These results demonstrate that the titled material would be an effective and easily regenerated adsorbent for CR removal from wastewater.

Enhanced nitrogen removal in an aerobic granular sequencing batch reactor under low DO concentration: Role of extracellular polymeric substances and microbial community structure.

In this study, the role of extracellular polymeric substances (EPSs) in nitrogen removal and the microbial community structure of aerobic granular sludge (AGS) were analyzed under different dissolved oxygen (DO) conditions (6-7, 4-5, and 2-3 mg·L-1). The EPSs transported and retained nitrogen in the denitrification process, and the total inorganic nitrogen (TIN) in the EPSs decreased from 6.09 to 5.54 mg·g-1 MLSS when the DO concentration decreased from 6-7 to 2-3 mg·L-1. The microbial community showed different core denitrifying bacterial populations involved in nitrogen removal in the AGS system under different DO conditions, with more species when they were higher relative abundances of denitrifying bacteria participating in the nitrogen removal process in AGS under low DO conditions, including Hydrogenophilaceae, Thauera, Enterobacter, Xanthomonadaceae_unclassified, Comalmonadaceae_unclassified, Nitrosomonas and Paracoccus. This study provides a more comprehensive understanding of the DO effect on the TIN removal mechanism by AGS.

Insight into the roles of tightly and loosely bound extracellular polymeric substances on a granular sludge in ammonium nitrogen removal.

To explicitly understand the function of extracellular polymeric substances in the treatment of ammonium-nitrogen-rich wastewater using aerobic granular sludge, the three forms of nitrogen (ammonium, nitrite and nitrate nitrogen) contained in tightly and loosely bound extracellular polymeric substances were analyzed. The three forms of nitrogen were monitored in the tightly and loosely bound extracellular polymeric substances in aerobic granular sludge after adsorption. The ammonium nitrogen contained in the extracellular polymeric substances was distributed in both the tightly and loosely bound forms and decreased gradually as the aeration time increased. Ammonium nitrogen remained in the tightly bound extracellular polymeric substances even after aeration was complete. The nitrite and nitrate nitrogen species in the extracellular polymeric substances were mainly present in the loosely bound extracellular polymeric substances. The sources of the three nitrogen forms detected in the extracellular polymeric substances differed relative to the different nitrogen forms.

Design and construction of linear laser encoders that possess high tolerance of mechanical runout.

A linearly diffracted laser encoder that has high tolerance of head-to-scale misalignment and a high signal-to-noise ratio is described. The preservation of parallelism between the incident and the diffracted beams, which can be attributed to a built-in folded 1x telescope, allows for the high alignment tolerance. It can be shown that, by coupling this newly developed circular polarization interferometer configuration with grating scale geometry optimization, one can eliminate the problems associated with signal distortion that arise from various efficiencies of the p- and the s-polarized light beams and obtain a high signal-to-noise ratio. Both theoretical and experimental results are presented to confirm the improved results and performance.