Endogenous cell wall degrading enzyme LytD is important for the biocontrol activity of Bacillus subtilis.

Autolysins are endogenous cell wall degrading enzymes (CWDEs) in bacteria that remodel the peptidoglycan layer of its own cell wall. In the Bacillus subtilis genome, at least 35 autolysin genes have been identified. However, the study of their roles in bacterial physiology has been hampered by their complexity and functional redundancy. B. subtilis GLB191 is an effective biocontrol strain against grape downy mildew disease, the biocontrol effect of which results from both direct effect against the pathogen and stimulation of the plant defense. In this study, we show that the autolysin N-acetylglucosaminidase LytD, a major autolysin of vegetative growth in B. subtilis, plays an important role in its biocontrol activity against grape downy mildew. Disruption of lytD resulted in reduced suppression of the pathogen Plasmopara viticola and stimulation of the plant defense. LytD is also shown to affect the biofilm formation and colonization of B. subtilis on grape leaves. This is the first report that demonstrates the role of an endogenous CWDE in suppressing plant disease infection of a biological control microorganism. These findings not only expand our knowledge on the biological function of autolysins but also provide a new target to promote the biocontrol activity of B. subtilis.

Tree phylogeny predicts more than litter chemical components in explaining enzyme activities in forest leaf litter decomposition.

Litter decomposition is an important process in ecosystem and despite recent research elucidating the significant influence of plant phylogeny on plant-associated microbial communities, it remains uncertain whether a parallel correlation exists between plant phylogeny and the community of decomposers residing in forest litter. In this study, we conducted a controlled litterbag experiment using leaf litter from ten distinct tree species in a central subtropical forest ecosystem in a region characterized by subtropical humid monsoon climate in China. The litterbags were placed in situ using a random experimental design and were collected after 12 months of incubation. Then, the litter chemical properties, microbial community composition and activities of enzyme related to the decomposition of organic carbon (C) and nitrogen (N) were assessed. Across all ten tree species, Alphaproteobacteria, Gammaproteobacteria, and Actinobacteria were identified as the predominant bacterial classes, while the primary fungal classes were Dothideomycetes, Sordariomycetes and Eurotiomycetes. Mantel test revealed significant correlations between litter chemical component and microbial communities, as well as enzyme activities linked to N and C metabolism. However, after controlling for plant phylogenetic distance in partial Mantel test, the relationships between litter chemical component and microbial community structure and enzyme activities were not significant. Random forest and structural equation modeling indicated that plant phylogenetic distance exerted a more substantial influence than litter chemical components on microbial communities and enzyme activities associated with the decomposition of leaf litter. In summary, plant phylogenic divergence was found to be a more influential predictor of enzyme activity variations than microbial communities and litter traits, which were commonly considered reliable indicators of litter decomposition and ecosystem function, thereby highlighting the previously underestimated significance of plant phylogeny in shaping litter microbial communities and enzyme activities associated with degradation processes in forest litter.

Influence of spatial structure migration of overlying strata on water storage of underground reservoir in coal mine.

Underground reservoir technology for coal mines can realize the coordinated development of coal exploitation and water protection in water-shortage-prone areas. The seepage effect of the floor seriously affects the safety of underground reservoirs under the action of mining damage and seepage pressure. Focusing on the problem of floor seepage in underground reservoirs, a spatial mechanical model of underground reservoirs was established. The main factors affecting the seepage of the surrounding rock were studied. The seepage pressure law in different stages of spatial structure evolution of overlying strata was explored. The results showed that pressure change was the main factor affecting the stability of a reservoir's surrounding rock. The pore space between the broken and fractured rock in the water-flowing fractured zone was the main water storage space, which was directly related to the development of a breaking arch. According to the spatial structure evolution process of the overlying strata, the water storage state of an underground reservoir was divided into two stages and three situations. The seepage pressure was mainly affected by the water pressure and the overlying strata weight. The water pressure was affected by the reservoir head height, and the overlying strata weight was mainly affected by the overlying strata thickness.

Real-world national trends and influencing factors preference of non-vitamin K antagonist oral anticoagulants in China.

Backgrounds: Non-vitamin K antagonist oral anticoagulants (NOACs) have been recommended as the first choice over warfarin for non-valvular atrial fibrillation (AF). However, there is limited data about their usage in mainland China. Methods: Prescriptions of patients diagnosed with AF and containing OACs were extracted from Hospital Prescription Cooperation Project from January 2016 to March 2021. The primary outcome was the changing percentage of different OACs. The secondary outcomes were frequencies as well as factors with the choice of different OACs and dosage of NOACs. Univariate and Multivariate logistic regressions were conducted to explore possible factors. All statistical analyses were performed using SAS software (Version 9.4). Results: Among the 220,083 distinct prescriptions diagnosed with AF and prescribed with OACs, the percentage of NOACs increased over years, exceeding warfarin in 2018. Until March 2021, 83.53% of included patients were prescribed with NOACs. Rivaroxaban (62.25%) and dabigatran (37.65%) were the most commonly prescribed NOACs. Low dosage was common for NOACs (44.54%), this was mainly driven by rivaroxaban, 67.98% of which were low dosage. Multivariate logistic regression indicated that several factors were positively associated with the preference of low dosage, including outpatients (OR 1.32, 95% CI 1.26-1.39), patients with hypertension (OR 1.49, 95% CI 1.40-1.58), acute coronary syndrome (OR 1.17, 95% CI 1.12-1.22), stroke (OR 1.42, 95% CI 1.33-1.52), and kidney disease (OR 1.63, 95% CI 1.34-1.97), as well as concomitantly using antiplatelet agents (OR 1.52, 95% CI 1.40-1.66), and steroids (OR 1.76, 95% CI 1.50-2.07). On the contrary, they were less common in health insurance holder (OR 0.79, 95% CI 0.75-0.84), patients taking apixaban (vs. rivaroxaban, OR 0.39, 95% CI 0.18-0.81), dabigatran (vs. rivaroxaban, OR 0.01, 95% CI 0.01-0.01), edoxaban (vs. rivaroxaban, OR 0.36, 95% CI 0.23-0.55), diagnosed with heart failure (OR 0.87, 95% CI 0.81-0.93), deep vein thrombosis (OR 0.36, 95% CI 0.29-0.46), pulmonary embolism (OR 0.35, 95% CI 0.28-0.43), and peripheral artery disease (OR 0.68, 95% CI 0.55-0.85). Conclusion: The usage of OACs for AF was overall complying with updated guidelines. Low dosage was common for NOACs, further studies were warranted to verify its effectiveness and explore the underlying mechanism.

Overbias Photon Emission from Light-Emitting Devices Based on Monolayer Transition Metal Dichalcogenides.

Tunneling light-emitting devices (LEDs) based on transition metal dichalcogenides (TMDs) and other two-dimensional (2D) materials are a new platform for on-chip optoelectronic integration. Some of the physical processes underlying this LED architecture are not fully understood, especially the emission at photon energies higher than the applied electrostatic potential, so-called overbias emission. Here we report overbias emission for potentials that are near half of the optical bandgap energy in TMD-based tunneling LEDs. We show that this emission is not thermal in nature but consistent with exciton generation via a two-electron coherent tunneling process.

Effect of Supplementary Light with Different Wavelengths on Anthocyanin Composition, Sugar Accumulation and Volatile Compound Profiles of Grapes.

Protected cultivation is currently one of the main cultivation modes for grape production, but the long-term use of plastic film will have a certain negative impact on the light environment in vineyards, which in turn causes poor colouring, low sugar content and a lack of aroma in some red grape varieties. Supplementing light can be an effective way to mitigate these problems. In this study, vines of three red table grape varieties ('Summer Black', 'Xinyu' and 'Queen Nina') cultivated in a plastic greenhouse were supplemented with red, blue, white and red-blue light from veraison to harvest. All four supplemental light treatments increased the content of anthocyanins, sugars and volatile compounds in three grape varieties compared to CK (no supplemental lighting). Red-blue light treatment was the most favourable for the accumulation of anthocyanins and sugars, and the grapes treated with blue light had the highest content of volatile compounds. The grapes treated with red-blue light all obtained the highest composite scores via principal component analysis. For most of the sensory properties, the highest scores were obtained by the red-blue light-treated grapes. The results of this study will be useful in improving the colouring, sugar, and aroma content of grapes under protected cultivation.

On strata damage and stress disturbance induced by coal mining based on physical similarity simulation experiments.

Extensive studies have been conducted on the movement of overlying strata when a single coal seam is mined. However, structural characteristics and associated stress field variation of the overlying strata over multiple coal seam mining remain unclear. Here we performed physical modelling experiments analogous to No. 42108 working face of Buertai coal mine, Shendong coalfield, where No. 22 coal seam (2.9 m thickness) was mined first, preceding No. 42 upper coal seam (6.1 m thickness) with an inter-coal-seam distance of 72.8 m. We employed DIC (digital image correlation) measurement and systematically-laid pressure cells to visualize the overlying strata movement and monitor stress field variations over multiple coal seam mining. We found that the stress of the inter-coal-seam strata increased significantly in the late mining stage of No. 22 coal seam due to the strata collapse, and culminated after compaction of the caved blocks. The inter-coal-seam strata stress gradually decreased over mining of No. 42 upper coal seam and arrived at zero after the inter-coal-seam strata collapsed. The mining of No. 42 upper coal seam aggravated the roof settlement of No. 22 coal seam; and the floor stress was noticeably lower than that of No. 22 coal seam due to the pressure-relief caused by the former mining activity. Our physical modelling findings advanced our understanding on structural characteristics and stress evolutions of overlying strata over multiple coal seam mining and offered guidance for prediction and mitigation of strata movement associated disasters in underground coal mining with geomechanical and mining conditions similar to those of Buertai coal mine.

Comparing the separation performance of poly(ethyleneimine) embedded butyric and octanoic acid based chromatographic stationary phases.

Poly(ethyleneimine) (PEI) modified silica spheres were used to graft butyric acid and octanoic acid onto their surfaces, forming two stationary phases named Sil-PEI-BAD and Sil-PEI-CAD, respectively. Characterized methods including fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA) and thermogravimetric analysis (TGA) were utilized to determine the successful synthesis of these two stationary phase materials. The chromatographic performance of these two stationary phases was analyzed with hydrophobic and hydrophilic compounds as analytes. Compared with Sil-PEI-CAD column, Sil-PEI-BAD column was more effective in separating hydrophilic compounds including nucleosides, alkaloids and vitamins. Hydrophobic substances including polycyclic aromatic hydrocarbons (PAHs) and alkylbenzenes obtained excellent separation results on Sil-PEI-CAD column than Sil-PEI-BAD column. Additionally, according to the separation of phenols, Sil-PEI-CAD column can be used in HILIC/RPLC mixed-mode. The results showed that the properties and retention mechanisms of the prepared stationary phases depended on the length of the alkyl chains bonded on the silica surface.

Exciton-assisted electron tunnelling in van der Waals heterostructures.

The control of elastic and inelastic electron tunnelling relies on materials with well-defined interfaces. Two-dimensional van der Waals materials are an excellent platform for such studies. Signatures of acoustic phonons and defect states have been observed in current-to-voltage measurements. These features can be explained by direct electron-phonon or electron-defect interactions. Here we use a tunnelling process that involves excitons in transition metal dichalcogenides (TMDs). We study tunnel junctions consisting of graphene and gold electrodes separated by hexagonal boron nitride with an adjacent TMD monolayer and observe prominent resonant features in current-to-voltage measurements appearing at bias voltages that correspond to TMD exciton energies. By placing the TMD outside of the tunnelling pathway, we demonstrate that this tunnelling process does not require any charge injection into the TMD. The appearance of such optical modes in electrical transport introduces additional functionality towards van der Waals material-based optoelectronic devices.

Population genomics reveals demographic history and selection signatures of hazelnut (Corylus).

Hazelnut (Corylus spp.) is known as one of the four famous tree nuts in the world due to its pleasant taste and nutritional benefits. However, hazelnut promotion worldwide is increasingly challenged by global climate change, limiting its production to a few regions. Focusing on the eurytopic Section Phyllochlamys, we conducted whole-genome resequencing of 125 diverse accessions from five geo-ecological zones in Eurasia to elucidate the genomic basis of adaptation and improvement. Population structure inference outlined five distinct genetic lineages corresponding to climate conditions and breeding background, and highlighted the differentiation between European and Asian lineages. Demographic dynamics and ecological niche modeling revealed that Pleistocene climatic oscillations dominantly shaped the extant genetic patterns, and multiple environmental factors have contributed to the lineage divergence. Whole-genome scans identified 279, 111, and 164 selective sweeps that underlie local adaptation in Corylus heterophylla, Corylus kweichowensis, and Corylus yunnanensis, respectively. Relevant positively selected genes were mainly involved in regulating signaling pathways, growth and development, and stress resistance. The improvement signatures of hybrid hazelnut were concentrated in 312 and 316 selected genes, when compared to C. heterophylla and Corylus avellana, respectively, including those that regulate protein polymerization, photosynthesis, and response to water deprivation. Among these loci, 22 candidate genes were highly associated with the regulation of biological quality. Our study provides insights into evolutionary processes and the molecular basis of how sibling species adapt to contrasting environments, and offers valuable resources for future climate-resilient breeding.

Fast electrochemical impedance spectroscopy of lithium-ion batteries based on the large square wave excitation signal.

Electrochemical impedance spectroscopy (EIS) is a technique for electrochemical characterization that is sensitive to the battery state and can uncover multidimensional electrochemical evolution information within the battery. Lithium-ion batteries usually need to be used in conjunction with power conversion circuits, while conventional EIS testing is conducted offline and is time-consuming, which cannot effectively monitor the battery characteristics during use. To match the characteristics of the square wave signal during power switching, a rapid EIS measurement method for lithium-ion batteries based on the large square wave excitation signal is proposed in this paper, and develops a testing device with a response time of microseconds. The proposed method and device are applied to estimate the state of health (SOH) of the battery. In conclusion, we proposed method enhances the capabilities of EIS testing technology and has a good application prospect in real-time online impedance monitoring.

Plastome phylogenomics provide new perspective into the phylogeny and evolution of Betulaceae (Fagales).

BACKGROUND: Betulaceae is a relatively small but morphologically diverse family, with many species having important economic and ecological values. Although plastome structure of Betulaceae has been reported sporadically, a comprehensive exploration for plastome evolution is still lacking. Besides, previous phylogenies had been constructed based on limited gene fragments, generating unrobust phylogenetic framework and hindering further studies on divergence ages, biogeography and character evolution. Here, 109 plastomes (sixteen newly assembled and 93 previously published) were subject to comparative genomic and phylogenomic analyses to reconstruct a robust phylogeny and trace the diversification history of Betulaceae. RESULTS: All Betulaceae plastomes were highly conserved in genome size, gene order, and structure, although specific variations such as gene loss and IR boundary shifts were revealed. Ten divergent hotspots, including five coding regions (Pi > 0.02) and five noncoding regions (Pi > 0.035), were identified as candidate DNA barcodes for phylogenetic analysis and species delimitation. Phylogenomic analyses yielded high-resolution topology that supported reciprocal monophyly between Betula and Alnus within Betuloideae, and successive divergence of Corylus, Ostryopsis, and Carpinus-Ostrya within Coryloideae. Incomplete lineage sorting and hybridization may be responsible for the mutual paraphyly between Ostrya and Carpinus. Betulaceae ancestors originated from East Asia during the upper Cretaceous; dispersals and subsequent vicariance accompanied by historical environment changes contributed to its diversification and intercontinental disjunction. Ancestral state reconstruction indicated the acquisition of many taxonomic characters was actually the results of parallel or reversal evolution. CONCLUSIONS: Our research represents the most comprehensive taxon-sampled and plastome-level phylogenetic inference for Betulaceae to date. The results clearly document global patterns of plastome structural evolution, and established a well-supported phylogeny of Betulaceae. The robust phylogenetic framework not only provides new insights into the intergeneric relationships, but also contributes to a perspective on the diversification history and evolution of the family.

Metformin Hydrochloride Mucosal Nanoparticles-Based Enteric Capsule for Prolonged Intestinal Residence Time, Improved Bioavailability, and Hypoglycemic Effect.

Metformin hydrochloride enteric-coated capsule (MH-EC) is a commonly used clinical drug for the treatment of type 2 diabetes. In this study, we described a metformin hydrochloride mucosal nanoparticles enteric-coated capsule (MH-MNPs-EC) based on metformin hydrochloride chitosan mucosal nanoparticles (MH-CS MNPs) and its preparation method to improve the bioavailability and hypoglycemic effect duration of MH-EC. In intestinal adhesion study, the residue rates of free drugs and mucosal nanoparticles were 10.52% and 67.27%, respectively after cleaned with PBS buffer. MH-CS MNPs could significantly improve the efficacy of MH and promote the rehabilitation of diabetes rats. In vitro release test of MH-MNPs-EC showed continuous release over 12 h, while commercial MH-EC released completely within about 1 h in intestinal environment (pH 6.8). Pharmacokinetic study was performed in beagle dogs compared to the commercial MH-EC. The durations of blood MH concentration above 2 µg/mL were 9 h for MH-MNPs-EC versus 2 h for commercial MH-EC. The relative bioavailability of MH-MNPs-EC was determined as 185.28%, compared with commercial MH-EC. In conclusion, MH-CS MNPs have good intestinal adhesion and can significantly prolong the residence time of MH in the intestine. MH-MNPs-EC has better treatment effect compared with MH-EC, and it is expected to be a potential drug product for the treatment of diabetes because of its desired characteristics.

Homomesoporous Metal-Organic Framework for High-Performance Electrochromatographic Separation.

Metal-organic frameworks (MOFs) have exhibited tremendous potential in the area of separation science. However, most of the developed MOF-based stationary phases contained only microporous structures and suffer from limited separation performance. Herein, homomesoporous MOFs with excellent mass transfer capability and strong thermodynamic interactions are first explored as the novel stationary phase for high-performance capillary electrochromatographic separations. As a proof of concept, noninterpenetrated mesoMOF-1 with uniform mesopore sizes (22.5 × 26.1 Å) and good stability was facilely grown on the inner surface of capillaries and applied as a homomesoporous MOF coating-based stationary phase for high-efficiency electrochromatographic separation. Seven types of analytes with different molecular dimensions were all baseline separated on a mesoMOF-1 coated column with high theoretical plate numbers and excellent repeatability, exhibiting significantly improved separation selectivity and column efficiency in comparison to a microporous HKUST-1 coated column. The maximum column efficiencies of the mesoMOF-1 coated column for substituted benzenes and halobenzenes reached up to 1.4 × 105 plates/m, and its mass loadability was also much higher than that of the HKUST-1 coated column. In addition, based on the analysis of adsorption kinetics and chromatographic retention behaviors, the interaction and retention mechanisms of different molecular-weight analytes on mesoMOF-1 coated stationary phases were systematically explored and disclosed in detail. These results indicate that the homomesoporous MOF-based stationary phase can effectively balance the kinetic diffusion (mass transfer capability) and thermodynamic interactions (the strength of adsorption interaction), having great potential for high-performance chromatographic separation.

Fault Diagnosis Method for Lithium-Ion Battery Packs in Real-World Electric Vehicles Based on K-Means and the Fréchet Algorithm.

Battery failure has traditionally been a major concern for electric vehicle (EV) safety, and early fault diagnosis will reduce many EV safety accidents. However, the short-circuit signal is generally very weak, so it is still a challenge to achieve a timely warning of battery failure. In this paper, an initial microfault diagnosis method is proposed for the data of electric vehicles in actual operation. First, a robust locally weighted regression data smoothing method is proposed that can effectively remove noisy data and retain fault characteristics. Second, an ordinary-least-squares-based voltage potential feature extraction method is proposed, which can effectively capture the small fault features of battery cells and achieve early warning. Third, a reference cell selection method based on K-means clustering is proposed, which can effectively reduce the false alarms caused by the inconsistency of each cell. Fourth, the Fréchet algorithm is introduced into the field of battery pack fault diagnosis and combined with thresholds for battery pack fault diagnosis and localization to accomplish the diagnosis and early warning of minor faults. Finally, the fault diagnosis method is validated by three actual running electric vehicles to verify the effectiveness, reliability, and robustness of the method.

Characteristics Scanning of Brain Structure and Function Changes in Patients with Different Degrees of Alzheimer's Disease.

Through the case control study on structural magnetic resonance imaging (sMRI) scanning, MR spectrum (MRS), and neuropsychological assessment of the intracranial structures of Alzheimer's disease (AD), patients of different degrees (early, middle, and late), the early clinical features, imaging features, and neuropsychological characteristics of patients with AD were analyzed to provide help for the early diagnosis of AD. The data of MR scanning of the brain, bilateral MRS scan of the hippocampus, thyroid function and other laboratory indicators, and neuropsychological evaluation analysis were collected in 50 patients who had been diagnosed with AD. According to CDR, 50 patients were divided into the early AD group and the middle and advanced AD group, with 23 patients in the early AD group and 27 patients in the middle and advanced AD group. Retrospective study was conducted to analyze the general conditions, medial temporal lobe atrophy (MTA) grading, and the metabolic changes of bilateral MRS in the hippocampus of patients in both groups, so did the mini-mental state examination (MMSE), activities of daily living scale (ADL), and other neuropsychological assessment results. Moreover, the comparative analysis was carried out. The results showed that the MTA grade of medial temporal atrophy increased with the progressive severity of the disease in both groups. A statistical test was conducted on the reduction of hippocampal volume in the two groups, and the P was less than 0.05. Therefore, the MTA scale was of great value in the diagnosis and staging of early AD. However, when the diagnosis of early AD was treated by MTA visual evaluation alone, there was 23.8% false negative diagnosis. If the judgment of early AD only depended on the metabolic changes of hippocampus MRS or MR scanning of intracranial structures, it was likely to cause false negative diagnosis. Therefore, the combination of MRS analysis and MR scanning of intracranial structures was favorable for the early diagnosis and treatment of AD. Combined with neuropsychological assessment, AD patients were staged more effectively, which greatly improved the accuracy of AD diagnosis in the early stage.

Intermittent voltage induced sludge polarization to enhance anaerobic digestion.

Intermittent voltage supply has been reported to improve the performance of electro-assisted anaerobic digestion but has not been well understood. In this study, an intermittent voltage of 0.6 V (1 day on-1 day off) was applied in an electro-assisted anaerobic digester to explore its effects. Compared to those without the voltage, the methane yield increased nearly by 20.0%, and organic decomposition increased by 9.5% with the intermittent voltage, which was similar to those with the continuous voltage. The amide groups of the sludge protein after the electro-treatment were polarized to enhance electron transfer and electron storage of protein-like substances of the sludge. Although the voltage was supplied intermittently, the increased conductivity and capacitance of the sludge and EPS could effectively transport electrons between exoelectrogens and electrotrophs (such as Firmicutes and Methanothrix) to promote the anaerobic digestion. This study explained the essence of electrochemical enhancement of anaerobic digestion from the perspective of molecular structure, that is, the polarization of functional groups by voltage could improve the sludge electro-activity to maintain effective interspecies electron transfer in the periodic voltage supply.

Preparation and evaluation of a double-hydrophilic interaction stationary phase based on bovine serum albumin and graphene quantum dots modified silica.

The bovine serum albumin (BSA) was firstly bonded on the surface of graphene quantum dots (GQDs) functionalized silica as the stationary phase named as BSA@GQDs@SiO2 which can perform hydrophilic interaction between the stationary phase and analytes. Characteristic methods including Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) were applied to estimate the chemical bonding results and morphological features of the prepared materials. In the chromatographic evaluation part, the BSA@GQDs@SiO2 column showed excellent separation efficiency for the analysis of hydrophilic compounds involving nucleosides and bases, acids, phenols, quinolones, vitamins and alkaloids, which proved the prepared column can exhibit hydrophilic interaction mode with other interactions including hydrogen bonding and electrostatic interaction. What's more, essential experimental approaches were designed to evaluate the retention properties of the prepared column via comparing with a commercial amino column and a prepared GQDs@SiO2 column. Results indicated the prepared column showed excellent separation ability for different kinds of hydrophilic compounds than commercial and single hydrophilic columns. The study showed that BSA@GQDs@SiO2 stationary phase with double hydrophilic materials will be a potential chromatographic material for analyzing various hydrophilic analytes.

Species divergence and phylogeography of Corylus heterophylla Fisch complex (Betulaceae): Inferred from molecular, climatic and morphological data.

Historical geo-climatic changes have shaped the geographical distributions and genetic diversity of numerous plant taxa in East Asia, which promote species divergence and ultimately speciation. Here, we integrated multiple approaches, including molecular phylogeography, ecological niche modeling, and morphological traits to examine the nucleotide diversity and interspecific divergence within Corylus heterophylla complex (C. heterophylla, C. kweichowensis, and C. yunnanensis). These three sibling taxa harbored similar high levels of nucleotide diversity at the species level. The molecular data (SCNG and cpDNA) unanimously supported the division of C. heterophylla complex into two major clades, with C. yunnanensis diverged earlier from the complex, whereas C. heterophylla and C. kweichowensis could hardly be separated. The split between the two clades (c. 12.89 Ma) coincided with the formation of Sichuan Basin in the middle Miocene, while the divergence among and within the five subclades (YUN1-YUN3, HK1-HK2) occurred from the late Miocene to the Pleistocene. C. heterophylla of northern China experienced glacial contraction and interglacial expansion during the Quaternary, whereas C. kweichowensis and C. yunnanensis of southern China presented population expansion even during the last glacial maximum. Despite of high levels of genetic admixture between C. heterophylla and C. kweichowensis, significant ecological and morphological discrepancy as well as incomplete geographic isolation indicated that adaptive evolution triggered by divergent selection may have played important roles in incipient ecological speciation.

One-pot method for the synthesis of ß-cyclodextrin and covalent organic framework functionalized chiral stationary phase with mixed-mode retention mechanism.

As a welcomed porous material, covalent organic frameworks (COFs) have many advantages and are widely used in various aspects. Particularly, COFs have aroused great attentions of scientists in chromatographic separation field due to their outstanding advantages, such as high stability, large specific surface area and multiple voids. However, endowing COFs with chirality to construct chiral stationary phase (CSP) function is still facing many challenges. Here, we firstly prepared a ß-cyclodextrin (ß-CD) and covalent organic framework functional silica CSP named as COF@CD@SiO2 by one-pot method to perform high performance liquid chromatography (HPLC) chiral separation. The morphology and structure of the synthesized stationary phase were investigated by a variety of characterization methods including Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), N2 adsorption experiment, powder X-ray diffraction (XRD) and elemental analysis (EA). The prepared stationary phase realized fast separation of six enantiomers in a short time. The separation mechanism was mainly ascribed to the inclusion complexation of ß-cyclodextrin and the mutli-interaction sites from COFs material. In conclusion, the prepared chiral column can be used to achieve fast separation of enantiomers with good stability and reproducibility. These results can open new avenue for using chiral COFs in liquid chromatographic separation.