Pangenome analyses of Clostridium butyricum provide insights into its genetic characteristics and industrial application.

Clostridium butyricum is a Gram-positive anaerobic bacterium known for its ability to produce butyate. In this study, we conducted whole-genome sequencing and assembly of 14C. butyricum industrial strains collected from various parts of China. We performed a pan-genome comparative analysis of the 14 assembled strains and 139 strains downloaded from NCBI. We found that the genes related to critical industrial production pathways were primarily present in the core and soft-core gene categories. The phylogenetic analysis revealed that strains from the same clade of the phylogenetic tree possessed similar antibiotic resistance and virulence factors, with most of these genes present in the shell and cloud gene categories. Finally, we predicted the genes producing bacteriocins and botulinum toxins as well as CRISPR systems responsible for host defense. In conclusion, our research provides a desirable pan-genome database for the industrial production, food application, and genetic research of C. butyricum.

Computational Screening of Promising Deep-Ultraviolet Light Emitters.

Deep-ultraviolet (DUV) light sources are technologically highly important, but DUV light-emitting materials are extremely rare; AlN and its alloys are the only materials known so far, significantly limiting the chemical and structural spaces for materials design. Here, we perform a high-throughput computational search for DUV light emitters based on a set of carefully designed screening criteria relating to the sophisticated electronic structure. In this way, we successfully identify 5 promising material candidates that exhibit comparable or higher radiative recombination coefficients than AlN, including BeGeN2, Mg3NF3, KCaBr3, KHS, and RbHS. Further, we unveil the unique features in the atomic and electronic structures of DUV light emitters and elucidate the fundamental genetic reasons why DUV light emitters are extremely rare. Our study not only guides the design and synthesis of efficient DUV light emitters but also establishes the genetic nature of ultrawide-band-gap semiconductors in general.

Solvent- and Catalyst-Free Synthesis of gem-Difluorinated and Polyfluoroarylated Compounds with Nucleophilic or Electrophilic Fluorine-Containing Reaction Partners, Respectively.

A novel, efficient and environmentally friendly solvent-free and catalyst-free approach for the synthesis of structurally diverse gem-difluorinated and polyfluoroarylated derivatives with readily available nucleophilic and electrophilic fluorine-containing reaction partners, difluoroenoxysilane and pentafluorobenzaldehyde, is described. This neat protocol is induced by the direct hydrogen-bond interactions between fluorinated and non-fluorinated reactants without the use of heavy metal catalysts or volatile organic solvents and with no need for column chromatographic separation for most cases.

Synthesis of gem-Difluoro-3,4-dihydro-2H-pyrans via a TfOH-Catalyzed [4 + 2] Annulation of Difluoroenoxysilanes with α-Cyano Chalcones.

Difluoroenoxysilane, a commonly used difluoroallylating reagent, has attracted considerable attention in recent years. However, its application in the annulation reaction for the construction of fluorinated heterocyclic compounds remains relatively limited. Presented here is the Brønsted acid-catalyzed efficient formal [4 + 2] annulation of difluoroenoxysilanes with α-cyano chalcones. The developed protocol demonstrates tolerance to various substituents under mild reaction conditions, providing a reliable approach to construct gem-difluoro-3,4-dihydro-2H-pyrans in good to excellent yields with high diastereoselectivities.

Synthesis of Fluorine-Containing Multisubstituted Oxa-Spiro[4,5]cyclohexadienones via a Fluorinated Alcohol-Catalyzed One-Pot Sequential Cascade Strategy.

In recent years, the application of fluorinated alcohols as solvents, cosolvents, or additives has become important in modern organic synthesis. However, their potential as efficient catalysts in organic synthesis has not been well-explored. In this article, we report on the development of a one-pot sequential cascade reaction of p-quinone methides with difluoroenoxysilanes using hexafluoroisopropanol as catalyst. This reaction allows for the preparation of fluorinated multisubstituted oxa-spiro[4,5]cyclohexadienones. By using 50 mol % 1,1,1,3,3,3-Hexafluoroisopropanol (HFIP), the reaction proceeds smoothly to yield 1,6-conjugated products, which are then subjected to oxidative dearomatization/hemiacetalization using PhI(OAc)2. The overall process affords moderate to high yields and excellent diastereoselectivities.

Methionine redox regulation of actin-interacting proteins primarily governs antioxidative signaling and response to the salvianolic acid B treatment in EA.hy926 cells.

Actin-interacting proteins are important molecules for filament assembly and cytoskeletal signaling within vascular endothelium. Disruption in their interactions causes endothelial pathogenesis through redox imbalance. Actin filament redox regulation remains largely unexplored, in the context of pharmacological treatment. This work focused on the peptidyl methionine (M) redox regulation of actin-interacting proteins, aiming at elucidating its role on governing antioxidative signaling and response. Endothelial EA.hy926 cells were subjected to treatment with salvianolic acid B (Sal B) and tert-butyl-hydroperoxide (tBHP) stimulation. Mass spectrometry was employed to characterize redox status of proteins, including actin, myosin-9, kelch-like erythroid-derived cap-n-collar homology-associated protein 1 (Keap1), plastin-3, prelamin-A/C and vimentin. The protein redox landscape revealed distinct stoichiometric ratios or reaction site transitions mediated by M sulfoxide reductase and reactive oxygen species. In comparison with effects of tBHP stimulation, Sal B treatment prevented oxidation at actin M325, myosin-9 M1489/1565, Keap1 M120, plastin-3 M592, prelamin-A/C M187/371/540 and vimentin M344. For Keap1, reaction site was transitioned within its scaffolding region to the actin ring. These protein M oxidation regulations contributed to the Sal B cytoprotective effects on actin filament. Additionally, regarding the Keap1 homo-dimerization region, Sal B preventive roles against M120 oxidation acted as a primary signal driver to activate nuclear factor erythroid 2-related factor 2 (Nrf2). Transcriptional splicing of non-POU domain-containing octamer-binding protein was validated during the Sal B-mediated overexpression of NAD(P)H dehydrogenase [quinone] 1. This molecular redox regulation of actin-interacting proteins provided valuable insights into the phenolic structures of Sal B analogs, showing potential antioxidative effects on vascular endothelium.

Highly Diastereoselective [3 + 2] Cycloaddition of Aziridines with Difluorinated Silyl Enol Ethers: Divergent Synthesis of 4,4-Difluoropyrrolidines and 4-Fluoropyrroles.

A highly diastereoselective [3 + 2] cycloaddition of aziridines with difluorinated silyl enol ethers has been developed. This approach provides a facile methodology for highly functionalized gem-difluorinated pyrrolidines in good to excellent yields with good functional group tolerance. A one-pot, two-step approach for synthesis of structurally interesting fluorinated pyrroles has also been developed through a cycloaddition/aromatization/desulfonation sequence. Moreover, readily available substrates, mild reaction conditions, and easy scale-up synthesis show practical advantages.

Association between occupational stress, occupational burnout, and depressive symptoms among medical staff during COVID-19: A cross-sectional study in Chongqing, China.

BACKGROUND: Studies have extensively examined the factors contributing to the onset of occupational stress, burnout, and depression. However, the relationship between these variables is limited. OBJECTIVE: This study aimed to explore the association between occupational stress, burnout, and depressive symptoms and to investigate the mediating effect of burnout between occupational stress and depressive symptoms in medical staff. METHODS: A cross-sectional survey was conducted among medical staff in Chongqing, China. The Core Occupational Stress Scale (COSS), Maslach Burnout Inventory: General Survey (MBI-GS), and Patient Health Questionnaire-9 (PHQ-9) were used to assess the status of occupational stress, burnout, and depressive symptoms, respectively. The bootstrapping analyses using SPSS PROCESS macros version 3 were conducted to examine mediating effects. RESULTS: The study conducted on medical staff in Chongqing revealed that the detection rates of occupational stress, occupational burnout, and depressive symptoms were 31.8%, 23.3%, and 30.3%, respectively. Hierarchical regression analysis revealed that occupational stress and burnout accounted for 19.3% (p <  0.001) and 18.8% (p <  0.001) of the variance in depressive symptoms, respectively. Mediation analysis showed that occupational stress indirectly affected depressive symptoms through the mediating effect of occupational burnout, with a mediation effect value of 0.13 (bootstrap 95% CI: 0.116-0.144) and the mediation effect accounting for 44.8% of the total effect. CONCLUSION: Our results indicated that occupational stress and burnout were predictors of depressive symptoms. Occupational stress had a significant indirect effect on depressive symptoms via burnout. These results suggest that reducing occupational stress and burnout could be effective strategies for preventing depression among medical staff.

The Prevalence and Correlated Factors of Occupational Stress, Cumulative Fatigue, and Musculoskeletal Disorders among Information Technology Workers: A Cross-Sectional Study in Chongqing, China.

Occupational stress, cumulative fatigue, and work-related musculoskeletal disorders (WMSDs) are major concerns in the field of occupational health. Previous studies on occupational health focused on key industries, such as medical care, while there were few related studies on Information Technology (IT) industry. Our study explored the factors influencing occupational stress, cumulative fatigue, and musculoskeletal disorders in the IT industry. We collected 1363 IT workers' valid questionnaires, of which 73.1% of participants were technicians in Chongqing, 2021. The core occupational stress scale (COSS), self-diagnosis checklist for the assessment of workers' accumulated fatigue and Chinese musculoskeletal disorders questionnaire were used to measure the occupational stress, cumulative fatigue, and musculoskeletal disorders of the respondents. Logistic regressions were used to explore the correlated factors affecting these indicators. The results showed that the prevalence of occupational stress, cumulative fatigue, and musculoskeletal disorders was 50.4%, 47%, and 72.3%, respectively. Working in the current position for 3-10 years was a common increased risk for all three indicators. Insomnia was associated with an increased risk of cumulative fatigue (Odds Ratio, OR = 2.156, p < 0.001) and musculoskeletal disorders (OR = 1.878, p < 0.001). Cumulative fatigue was also associated with an increased risk of having WMSDs (OR = 3.207, p < 0.001). According to our findings, occupational factors, such as long working years, overtime work, and personal lifestyle, are highly related to the occurrence of occupational stress, cumulative fatigue, and musculoskeletal disorders for IT industry workers. More attention should be paid to women and those with long working hours in the IT industry.

Synthesis of Fluorinated Pyrrolo[2,1-a]isoquinolines through Decarboxylative/Dehydrofluorinative [3 + 2] Cycloaddition Aromatization of Isoquinolinium N-Ylides with Difluoroenoxysilanes.

A decarboxylative/dehydrofluorinative formal [3 + 2] cycloaddition aromatization of isoquinolinium N-ylides with difluoroenoxysilanes has been developed. This methodology provides a facile and straightforward synthetic pathway to afford highly functionalized fluorinated pyrrolo[2,1-a]isoquinolines in good to excellent yields under mild conditions. Moreover, gram-scale and synthetic derivatization experiments for the late-stage functionalization of drug molecules have also been demonstrated.

Machine Learning-Enabled Superior Energy Storage in Ferroelectric Films with a Slush-Like Polar State.

Heterogeneities in structure and polarization have been employed to enhance the energy storage properties of ferroelectric films. The presence of nonpolar phases, however, weakens the net polarization. Here, we achieve a slush-like polar state with fine domains of different ferroelectric polar phases by narrowing the large combinatorial space of likely candidates using machine learning methods. The formation of the slush-like polar state at the nanoscale in cation-doped BaTiO3 films is simulated by phase field simulation and confirmed by aberration-corrected scanning transmission electron microscopy. The large polarization and the delayed polarization saturation lead to greatly enhanced energy density of 80 J/cm3 and transfer efficiency of 85% over a wide temperature range. Such a data-driven design recipe for a slush-like polar state is generally applicable to quickly optimize functionalities of ferroelectric materials.

Lactobacillus rhamnosus and L. plantarum Combination Treatment Ameliorated Colitis Symptoms in a Mouse Model by Altering Intestinal Microbial Composition and Suppressing Inflammatory Response.

SCOPE: Changes in composition of intestinal microbes may disrupt the balance of their interaction with a susceptible host, resulting in development of inflammatory bowel disease (IBD). METHODS AND RESULTS: The study applied in combination two Lactobacillus strains (L. rhamnosus BY-02, L. plantarum BY-05) ("LS treatment"), previously isolates from feces of healthy human infants, in a mouse model of dextran sodium sulfate (DSS)-induced colitis, and evaluates their ameliorative effect and its possible mechanism. LS treatment suppresses weight loss and colon shortening, and reduces disease activity index in the mice. It also has several additional beneficial effects: i) maintains goblet cell numbers and ameliorates intestinal barrier damage in colonic tissue; ii) alters intestinal microbial composition close to normal by increasing abundances of Muribaculaceae, Akkermansia, Clostridia, Oscillospiraceae, and Lachnospiraceae, and decreasing abundance of Escherichia-Shigella; iii) increases content of short-chain fatty acids; iv) reduces content of pro-inflammatory lipopolysaccharides; v) suppresses overactivation of TLR4/NF-κB inflammatory signaling pathway. CONCLUSION: Combination treatment with two Lactobacillus strains strongly ameliorates colitis symptoms in the mouse model by favorably altering intestinal microbial composition and suppressing inflammatory response.

Synthesis of Difluoromethylated Carbinols via a HFIP-Promoted Hydroxydifluoromethylation of Aniline, Indole, and Pyrrole Derivatives with Difluoroacetaldehyde Ethyl Hemiacetal.

A hexafluoroisopropanol (HFIP)-promoted hydroxydifluoromethylation of aniline, indole, and pyrrole derivatives with difluoroacetaldehyde ethyl hemiacetal has been developed. This protocol provides a facile and straightforward approach to access diverse difluoromethylated carbinols in good to excellent yields under mild conditions. Furthermore, gram-scale and synthetic derivatization experiments have also been demonstrated.

Chemiluminescence Immunoassay Method of Urinary Liver Fatty-acid-binding Protein as a Promising Candidate for Kidney Disease.

Liver fatty acid binding protein (L-FABP) is an intercellular lipid chaperone protein that selectively combines with unsaturated free fatty acids and transports them to mitochondria or peroxisomes. L-FABP is a promising biomarker for the early detection of renal diseases in humans. Herein a chemiluminescence method (CLIA) was demonstrated to measure the level of urinary L-FABP in the urinary samples. An anti-(L-FABP)-magnetic beads complex was prepared to capture the analyte target. Sensitivity, precision, accuracy, interference effect, high-dose hook effect of the developed assay were evaluated. Under the suitable experimental parameters, the established method have a wide linear range (0.01-10 ng/mL) and also showed a sufficiently low limit of detection of 0.0060 ng/mL. Besides, the satisfactory recoveries of the method in the urinary were ranged from 97.74%-112.32%, which was well within the requirement of clinical analysis. Furthermore, this proposed method has been successfully applied to the clinical determination of L-FABP in patients who have been diagnosed with kidney disease. The results showed that CLIA could accurately and rapidly determine the urinary level of L-FABP with high-throughput, which could be useful as a new tool to predict complications in patients with kidney disease. The clinical trial was approved by Shuyang Hospital of Traditional Chinese Medicine Ethics Committee: 20,210,202-001 at February 2, 2021.

Biomimetic navigation system using a polarization sensor and a binocular camera.

With the vigorous development of vision techniques, simultaneous localization and mapping (SLAM) has shown the capability of navigating autonomous robots in global-navigation-satellite-system-denied environments. However, the long-term robust navigation of lightweight autonomous robots in outdoor environments with complex interferences, such as illumination change, dynamic objects, and electromagnetic interference, is still a great challenge. In this paper, a polarization sensor-aided SLAM (POL-SLAM) that can provide absolute heading constraints for pure SLAM is proposed. POL-SLAM is a lightweight, tightly coupled system consisting of a polarization sensor and binocular camera. By means of an initialization that uses a polarization sensor, an absolute heading angle for the entire map is designed. Additionally, an algorithm to eliminate mismatching points using the matching point vector is proposed. The objective function of bundle adjustment is then deduced according to the re-projection error and polarization sensor. The vehicle test shows that the yaw and trajectory accuracies of POL-SLAM are significantly improved compared to pure SLAM. The yaw and trajectory accuracies are increased by 43.1% and 36.6%, respectively. These results indicate that the proposed POL-SLAM can improve the reliability and robustness of pure SLAM and can be used in lightweight autonomous robots in outdoor environments.

Development and application of a rapid all-in-one plasmid CRISPR-Cas9 system for iterative genome editing in Bacillus subtilis.

BACKGROUND: Bacillus subtilis, an important industrial microorganism, is commonly used in the production of industrial enzymes. Genome modification is often necessary to improve the production performance of cell. The dual-plasmid CRISPR-Cas9 system suitable for iterative genome editing has been applied in Bacillus subtilis. However, it is limited by the selection of knockout genes, long editing cycle and instability. RESULTS: To address these problems, we constructed an all-in-one plasmid CRISPR-Cas9 system, which was suitable for iterative genome editing of B. subtilis. The PEG4000-assisted monomer plasmid ligation (PAMPL) method greatly improved the transformation efficiency of B. subtilis SCK6. Self-targeting sgRNArep transcription was tightly controlled by rigorous promoter PacoR, which could induce the elimination of plasmids after genome editing and prepare for next round of genome editing. Our system achieved 100% efficiency for single gene deletions and point mutations, 96% efficiency for gene insertions, and at least 90% efficiency for plasmid curing. As a proof of concept, two extracellular protease genes epr and bpr were continuously knocked out using this system, and it only took 2.5 days to complete one round of genome editing. The engineering strain was used to express Douchi fibrinolytic enzyme DFE27, and its extracellular enzyme activity reached 159.5 FU/mL. CONCLUSIONS: We developed and applied a rapid all-in-one plasmid CRISPR-Cas9 system for iterative genome editing in B. subtilis, which required only one plasmid transformation and curing, and accelerated the cycle of genome editing. To the best of our knowledge, this is the rapidest iterative genome editing system for B. subtilis. We hope that the system can be used to reconstruct the B. subtilis cell factory for the production of various biological molecules.

Modification of polylactide by poly(ionic liquid)-b-polylactide copolymer and bio-based ionomers: Excellent toughness, transparency and antibacterial property.

Polylactide (PLA) is one of the most attractive bioplastics as it can be produced from nontoxic renewable feedstock. However, its inherently poor toughness greatly limits its large-scale application. Cost-effectively toughening PLA without sacrificing its transparency remains a big challenge. We herein prepared an imidazolium-based poly(ionic liquid)-b-PLA copolymer (ILA) and ionomers as toughening agent for PLA through an integrative approach including continuous-monomer-feeding copolymerization, quaternization reaction, ion exchange and inter-ionomers blending. By blending PLA with the ILA and ionomers, we successfully obtained PLA materials with combined features including high toughness, good transparency and antibacterial properties. The effects of regulated ionomer composition and ILA compatibilizer on phase morphology, mechanical properties and transparency of the blends were systematically studied. The optimum formulation (PLA/E12/ILA 60/40/5) shows an impressive transmittance of 89-93 %, high impact strength of 45 kJ/m2 and elongation at break at 170 %, which are about 17 and 24 times that of pure PLA, respectively. More interestingly, the presence of imidazolium cation and anion groups endows the blends with attractive antibacterial properties. Ion exchange between ILA copolymer and the imidazolium-containing ionomeric system leads to a synergistic effect of compatibilization and efficient toughening, providing a new strategy for develop high performance PLA materials.

Ultra-Tough Polylactide/Bromobutyl Rubber-Based Ionomer Blends via Reactive Blending Strategy.

A series of ultra-toughened sustainable blends were prepared from poly(lactic acid) (PLA) and bromobutyl rubber-based ionomers (i-BIIRs) via reactive blending, in which dicumyl peroxide (DCP) and Joncryl®ADR-4440 (ADR) were used as reactive blending additives. The miscibility, phase morphology and mechanical property of the PLA/i-BIIRs blends were thoroughly investigated through DMA, SEM, tensile and impact tests. The influence of different ionic groups and the effects of DCP and ADR on the compatibility between the phases, phase structure and mechanical properties were analyzed. The introduction of the imidazolium-based ionic groups and the reactive agents enable the i-BIIRs play multiple roles as effective compatibilizers and toughening agents, leading to improved interfacial compatibility and high toughness of the blends. The mechanical properties test showed that the PLA/i-BIIRs blends exhibit excellent toughness: impact strength and the elongation at break of AR-OH(30)+AD reached 95 kJ/m2 and 286%, respectively. The impact fracture surface showed the large-scale plastic deformation of the PLA matrix in the blends, resulting in greatly absorbing the impact energy. The results proved that simultaneously applying reactive blend and multiple intermolecular interactions methods is an effective toughening strategy for toughening modification of the PLA blends.

Extraordinary Antiwear Properties of Graphene-Reinforced Ti Composites Induced by Interfacial Decoration.

The expected excellent lubricant effect of graphene in metals during friction and wear is rarely achieved because of the difficulty in synthesizing suitable interfaces. Particularly, the situation is more challenging in titanium (Ti) matrix composites (TMCs) because of the high chemical-interface-reaction tendency between graphene and Ti during composite fabrication. In this study, few-layered graphene (FLG) decorated with SiC nanoparticles (SiCp) was synthesized as reinforcement in Ti-6Al-4V alloy to improve the interface of the composites. It was found that interfacial SiCp not only strengthened the interface bonding by the Si solid solution but also inhibited the chemical reaction between FLG and the Ti matrix with reduced sp3 defects. The composite with 30 wt % SiC-decorated FLG showed an 86.8% decrement in wear rate compared to the unreinforced matrix, resulting in exceptionally high antiwear enhancing efficiency, which was around fourfold of the available values of other TMCs in the literature. The antiwear mechanism was investigated by thorough characterization of the interfaces and microstructures of the composites. The idea of interfacial decoration can be potentially applied to other nanocarbon/metal composites with the advantages of retaining the function performance of nanocarbon materials.

HFIP-Promoted Selective Hydroxyalkylation of Aniline Derivatives with Arylglyoxal Hydrates.

A HFIP-promoted highly selective hydroxyalkylation of aniline derivatives with arylglyoxal hydrates has been realized. The reaction produces various N,N-dialkylanilines and their derivatives with α-hydroxy carbonyl units in good to excellent yields under mild conditions. Furthermore, the synthetic potential of this method has been demonstrated by the facile synthesis of several structurally interesting molecules such as benzil, 1,2,4-triazine, quinoxaline, hydantoin, and 2-thiohydantoin with aromatic amine units.