Radical fluorine transfer catalysed by an engineered nonheme iron enzyme.

Nonheme iron enzymes stand out as one of the most versatile biocatalysts for molecular functionalization. They facilitate a wide array of chemical transformations within biological processes, including hydroxylation, chlorination, epimerization, desaturation, cyclization, and more. Beyond their native biological functions, these enzymes possess substantial potential as powerful biocatalytic platforms for achieving abiological metal-catalyzed reactions, owing to their functional and structural diversity and high evolvability. To this end, our group has recently engineered a series of nonheme iron enzymes to employ non-natural radical-relay mechanisms for abiological radical transformations not previously known in biology. Notably, we have demonstrated that a nonheme iron enzyme, (S)-2-hydroxypropylphosphonate epoxidase from Streptomyces viridochromogenes (SvHppE), can be repurposed into an efficient and selective biocatalyst for radical fluorine transfer reactions. This marks the first known instance of a redox enzymatic process for C(sp3)F bond formation. This chapter outlines the detailed experimental protocol for engineering SvHPPE for fluorination reactions. Furthermore, the provided protocol could serve as a general guideline that might facilitate other engineering endeavors targeting nonheme iron enzymes for novel catalytic functions.

Study on the mechanism of action of methane production by co-fermentation of sludge and lignite.

To improve the methanogenic efficiency of lignite anaerobic fermentation and explore innovative approaches to sludge utilization, a co-fermentation technique involving lignite and sludge was employed for converting biomass into biomethane. Volatile suspended solids were introduced as a native enrichment of the sludge and mixed with lignite for fermentation. The synergistic fermentation mechanism between sludge and lignite for biomethane production was analyzed through biochemical methane potential experiments, measurement of various parameters pre- and post-fermentation, observation of bacterial population changes during the peak of reaction, carbon migration assessment, and evaluation of rheological characteristics. The results showed that the addition of sludge in the anaerobic fermentation process improved the microorganisms' ability to degrade lignite and bolstered biomethane production. Notably, the maximum methane production recorded was 215.52 mL/g-volatile suspended solids, achieved at a sludge to coal ratio of 3:1, with a synergistic growth rate of 25.37%. Furthermore, the removal rates of total suspended solids, and total chemical oxygen demand exhibited an upward trend with an increasing percentage of sludge in the mixture. The relative abundance and activity of the methanogens population were found to increase with an appropriate ratio of sludge to lignite. This observation confirmed the migration of carbon between the solid-liquid-gas phases, promoting enhanced system affinity. Additionally, the changes in solid-liquid phase parameters before and after the reaction indicated that the addition of sludge improved the system's degradation capacity. The results of the study hold significant implications in realizing the resource utilization of sludge and lignite while contributing to environmental protection endeavors.

Analysis of landfill leachate promoting efficient application of weathered coal anaerobic fermentation.

This research aimed to develop a new method for clean utilization and treatment of landfill leachate and solid waste weathered coal. Landfill leachate and weathered coal were adopted for combined anaerobic fermentation for methane production. The characteristics of microbial community, mechanism of biological methane production, and utilization characteristics of fermentation broth and solid residue for co-fermentation were analyzed through metagenomics, soluble organic matter detection and thermogravimetric (TG) analysis. The obtained results revealed that combined anaerobic fermentation increased methane production by 80.1%. Syntrophomonas, Salipiger, Methanosaeta and Methanothrix were highly correlated. Gene abundances of 2-oxoacid ferredoxin oxidoreductase and enolase were increased in methane conversion pathway mainly by acetic acid. Pyruvate-ferroredoxin oxidoreductase, 2-oxoglutarate synthase and succinate dehydrogenase acetate synthase intensified electron transfer pathways among microorganisms. Fulvic acid, tyrosine and tryptophan contents were high in fermentation broth. Volatile decomposition temperature, ignition point and residual char combustion temperature of residual coal were decreased and combustion was more stable. The obtained results showed that the co-fermentation of landfill leachate and weathered coal improved biological methane gas production, degraded weathered coal and improved combustion performance, which provided a new idea for weathered coal clean utilization.

Analysis on methane production from various coal slime fermentations based on metagenomics.

Metagenomic sequencing technology was applied to evaluate differences in the anaerobic fermentation process of coal slimes by analyzing microbial diversity, functional activity structure, and cooperative relationship during the anaerobic fermentation of coal slimes with different coal ranks. The obtained results showed that the production of biomethane from coal slime was decreased by increasing metamorphism degree. Internal reason was higher abundance of microbial community in low rank coal slimes compared to that in high rank coal which had higher activity in the gene expression of key steps such as hydrolysis and acidification, methanation and the production of hydrogen and acetic acid. Acetic acid decarboxylation and CO2 reduction are two key pathways of methanation process. At the same time, K11261 (formylmethanofuran dehydrogenase subunit) and K01499 (methenyltetrahydromethanopterin cyclohydrolase) genes were further enriched in low rank slime systems, which enhanced the proportion of CO2 reduction in methanation pathway and was beneficial to biomethane production. Research revealed the roles of different coal slime ranks in biomethane production process and is considered as an important reference significance for further exploration of coal slime resource utilization.

Metagenomic characterization of biomethane transformation by lipid-catalyzed anaerobic fermentation of lignite.

The present study aims at using lipid in a novel way to improve the efficiency of methane production from lignite anaerobic digestion. The obtained results showed an increase by 3.13 times of the cumulative biomethane content of lignite anaerobic fermentation, when 1.8 g lipid was added. The gene expression of functional metabolic enzymes was also found to be enhanced during the anaerobic fermentation. Moreover, the enzymes related to fatty acid degradation such as long-chain Acyl-CoA synthetase and Acyl-CoA dehydrogenase were increased by 1.72 and 10.48 times, respectively, which consequently, accelerated the conversion of fatty acid. Furthermore, the addition of lipid enhanced the carbon dioxide trophic and acetic acid trophic metabolic pathways. Hence, the addition of lipids was argued to promote the production of methane from lignite anaerobic fermentation, which provided a new insight for the conversion and utilization of lipid waste.

Seasonal variation of microbial community and methane metabolism in coalbed water in the Erlian Basin, China.

Coalbed water is a semi-open system connecting underground coalbeds with the external environment. Microorganisms in coalbed water play an important role in coal biogasification and the carbon cycle. The community assemblages of microorganisms in such a dynamic system are not well understood. Here, we used high-throughput sequencing and metagenomic analysis to investigate microbial community structure and identify the potential functional microorganisms involved in methane metabolism in coalbed water in the Erlian Basin, a preferred low-rank coal bed methane (CBM) exploration and research area in China. The results showed that there were differences in the responses of bacteria and archaea to seasonal variation. Bacterial community structure was affected by seasonal variation but archaea was not. Methane oxidation metabolism dominated by Methylomonas and methanogenesis metabolism dominated by Methanobacterium may exist simultaneously in coalbed water.

Physical, chemical, and bio-pretreatments on microbial gas production in Baode Block coal.

Currently, the exploitation of Baode Block as a biogenic coal-bed gas field has been in the later stage of stable production; hence, exploration and activation of microbial gas production are of great practical significance for the enhancement and stabilization of block production. Pretreatment is the key process to improve anaerobic biodegradation performance and increase yield and production rate of gas. In this study, we examine physical, chemical, and biological pretreatment methods and compare their effectiveness toward microbial gas production in the coal seam. The obtained results indicate that: (1) grinding can enhance contact between the coal sample and bacteria liquid, and coal powder has greater gas-producing performance than the coal lump. (2) Chemical pretreatment of coal samples using acid and base can enhance gas production capacity. NaOH treatment has better gas-producing performance than HCl treatment, and the activity of microbial flora is higher after treatment. (3) Biological pretreatment can greatly enhance the microbial degradation of coal bed. The highest gas yield after white rot fungus pretreatment is 11.65 m3/t, and gas production cycle is shorter than before. This may be due to the white rot fungus effectively degrading macromolecules and, therefore, shortening the duration of methanogenic hydrolysis, which provides more organic matter for methanogens to decompose. During production, in addition to selecting a proper pretreatment method, the treatment cost and balance between energy input of pretreatment and gas energy output must also be considered. The joint pretreatment between different reagents and treatment methods is a possible solution to the problem and a current research trend to realize the large-scale degradation of coal. The simulated microbial methane production of coal seam is feasible for Baode Block in Ordos, where coal samples in this block have great gas-producing potential after treatment, and provides good references for further in-field tests.

Recent Advances in Woven Spacer Fabric Sandwich Composite Panels: A Review.

Because of the advantageous characteristics of strong integrity, lightweight, high performance, and various designs, woven spacer fabric (WSF) and its composite are extensively used in construction, traffic, and aerospace, among other fields. This paper first describes the WSF structure, including core yarns and cross-linking, and then discusses the influence of the processing parameters, among angle of the wall decisive the failure mode on the plate properties. Moreover, we summarize the molding and filling technology of WSF composite sandwich panels and discuss the process order, resulting in a significant effect on the stiffness of the sandwich composite plate; the current processing is mostly hand lay-up technology. In addition, we introduce the core and matrix material of the sandwich composite plate, which are mainly polyurethane (PU) foam and epoxy resin (70% of matrix material), respectively. Finally, the mechanical properties of WSF composite sandwich panels are summarized, including bending, compression, impact, shear, and peel properties. Factors influencing the mechanical properties are analyzed to provide a theoretical basis for future plate design and preparation.

The CfSnt2-Dependent Deacetylation of Histone H3 Mediates Autophagy and Pathogenicity of Colletotrichum fructicola.

Camellia oleifera is one of the most valuable woody edible-oil crops, and anthracnose seriously afflicts its yield and quality. We recently showed that the CfSnt2 regulates the pathogenicity of Colletotrichum fructicola, the dominant causal agent of anthracnose on C. oleifera. However, the molecular mechanisms of CfSnt2-mediated pathogenesis remain largely unknown. Here, we found that CfSnt2 is localized to the nucleus to regulate the deacetylation of histone H3. The further transcriptomic analysis revealed that CfSnt2 mediates the expression of global genes, including most autophagy-related genes. Furthermore, we provided evidence showing that CfSnt2 negatively regulates autophagy and is involved in the responses to host-derived ROS and ER stresses. These combined functions contribute to the pivotal roles of CfSnt2 on pathogenicity. Taken together, our studies not only illustrate how CfSnt2 functions in the nucleus, but also link its roles on the autophagy and responses to host-derived stresses with pathogenicity in C. fructicola.

The Patent Foramen Ovale and Migraine: Associated Mechanisms and Perspectives from MRI Evidence.

Migraine is a common neurological disease with a still-unclear etiology and pathogenesis. Patent foramen ovale (PFO) is a kind of congenital heart disease that leads to a right-to-left shunt (RLS). Although previous studies have shown that PFO has an effect on migraine, a clear conclusion about the link between PFO and migraine is lacking. We first summarized the PFO potential mechanisms associated with migraine, including microembolus-triggered cortical spreading depression (CSD), the vasoactive substance hypothesis, impaired cerebral autoregulation (CA), and a common genetic basis. Further, we analyzed the changes in brain structure and function in migraine patients and migraine patients with PFO. We found that in migraine patients with PFO, the presence of PFO may affect the structure of the cerebral cortex and the integrity of white matter, which is mainly locked in subcortical, deep white matter, and posterior circulation, and may lead to changes in brain function, such as cerebellum and colliculus, which are involved in the processing and transmission of pain. In summary, this paper provides neuroimaging evidence and new insights into the correlation between PFO and migraine, which will help to clarify the etiology and pathogenesis of migraine, and aid in the diagnosis and treatment of migraine in the future.

Directed evolution of nonheme iron enzymes to access abiological radical-relay C(sp3)-H azidation.

We report the reprogramming of nonheme iron enzymes to catalyze an abiological C(sp3)‒H azidation reaction through iron-catalyzed radical relay. This biocatalytic transformation uses amidyl radicals as hydrogen atom abstractors and Fe(III)‒N3 intermediates as radical trapping agents. We established a high-throughput screening platform based on click chemistry for rapid evolution of the catalytic performance of identified enzymes. The final optimized variants deliver a range of azidation products with up to 10,600 total turnovers and 93% enantiomeric excess. Given the prevalence of radical relay reactions in organic synthesis and the diversity of nonheme iron enzymes, we envision that this discovery will stimulate future development of metalloenzyme catalysts for synthetically useful transformations unexplored by natural evolution.

The metabolic process of methane production by combined fermentation of coal and corn straw.

The anaerobic degradation of coal combined with straw biomass can promote the methane production. The biogas production potential and metabolic pathway were explored via the co-digestion simulation experiment of coal and corn straw. The results showed that 2 g of corn straw combined respectively with 4 g of bituminous coal A, 6 g of bituminous coal B and 4 g of bituminous coal C resulted in highest methane yields. The structure of lignocellulose in corn straw was partially degraded into guaiacyl and syringyl units. Meanwhile, the content of biodegradable tyrosine like protein and soluble microbial by-products in liquid phase significantly decreased. Significantly, the structure of archaea altered from aceticlastic to hydrogenotrophic methanogens when the fermentation substrate changed from high to low rank coal. The proportion of hydrogenotrophic methanogens was significantly higher than that of aceticlastic and methylotrophic methanogens, and the hydrogenotrophic pathway was dominant than the aceticlastic pathway.

Association of Early Inflammation with Age and Asymptomatic Disease in COVID-19.

BACKGROUND: Disease severity in COVID-19 ranges from asymptomatic infection to severe disease and death, especially in older subjects. The risk for severe infection and death has been reported to be 2X in those between 30 and 40 years, 3X in those between 40 and 50 years, and 4X in those between 50 and 65 years, compared to the reference group of 18-29 years. OBJECTIVE: To investigate the early changes in host immune responses that are altered with age and the difference in the early host inflammatory response that dictates a symptomatic versus asymptomatic course of COVID-19. PATIENTS AND METHODS: COVID-19 subjects were identified by screening at the airport upon arrival from a foreign destination to China. Patients were either asymptomatic or had a mild disease when the first oro-pharyngeal (OP) swab samples were collected. Patients were quarantined and blood and throat swabs were collected during the course of the disease, allowing identification of the earliest host response to COVID-19. These patients were followed until their OP sample turned COVID-19 negative. RESULTS: Data were obtained from 126 PCR-confirmed COVID-19 patients. The blood samples were obtained within 48 days of qPCR confirmation of viral infection. Older subjects (>30 years) had significantly elevated levels of anti-inflammatory cytokine IL-10, a significant decrease in the percentage of CD8+ T cells, and expansion in NKT cell fraction. This was associated with significantly elevated viral load and a delayed humoral response in older subjects. Compared to symptomatic subjects, asymptomatic patients had an early increase in pro-inflammatory cytokine IL-2, while a decrease in both T regulatory cells and anti-inflammatory cytokine IL-10. Further, asymptomatic disease was associated with early humoral response and faster viral clearance. CONCLUSION: Early inflammatory response potentially plays a critical role for host-defense in COVID-19. The impaired early inflammatory response was associated with older age while a robust early inflammation was associated with asymptomatic disease.

Overall control herbal medicine in best consistency.

The standard preparation (SP) based on the quantitative fingerprint was proposed to control the quality of compound licorice tablets (CPLTs) in this paper, which is a great way to control the quality consistency nowadays. Here, taking China 145 batches of CPLTs from 9 manufacturers as samples to set up High Performance Liquid Chromatography fingerprints and CPLT-SP, and employing the systematically quantified fingerprint method (SQFM) combined five markers' contents to evaluate their quality. The results showed that all samples were qualified. The quantitative analysis of multi-components by single-marker (QAMS) for the determination of five components in CPLTs was applied, and there was no striking diversity in the results compared to the standard curve method. Furthermore, the correlation between raw materials and preparation of CPLTs was studied for predicting quality intelligently. As well as the ultraviolet full fingerprint dissolution was applied to evaluate the rationality of preparation. The results demonstrated that SQFM based on SP can integrally and perfectly control the quality of HD in best consistency.

Autophagy-related long noncoding RNAs can predict prognosis in patients with bladder cancer.

We investigated whether autophagy-related long noncoding RNAs (lncRNAs) can predict prognosis in bladder cancer. We obtained bladder cancer lncRNA data from The Cancer Genome Atlas and autophagy-related genes from the Human Autophagy Database. Fifteen autophagy-related lncRNAs with prognostic significance were identified. Multivariate Cox analysis was used to construct a risk score model, which divided bladder cancer patients into high-risk and low-risk groups. We found that patients in the low-risk group had better survival than those in the high-risk group. Subgroup analysis showed that patients in the high-risk group also had worse OS than that in the low-risk group in subgroups based on age, gender, clinical stage, and TNM stage. We next established a nomogram according to the results of multivariate Cox regression, which included age, gender, clinical stage, TNM stage, and risk score. The area under the curve for 3- and 5-year overall survival predicted by the nomogram were 0.711 and 0.719, respectively. Bioinformatics analysis demonstrated that the 15 identified lncRNAs are involved in the cell cycle, DNA replication, cell adhesion, cancer pathway, WNT signaling pathway, and oxidative stress. These findings confirm that autophagy-related lncRNAs are predictive of prognosis in bladder cancer patients and may affect tumor progression.

A retrospective analysis of risk factors associated with catheter-related thrombosis: a single-center study.

BACKGROUND: Catheter-related thrombosis may lead to catheter infections and failure, further deep venous thrombosis, and pulmonary embolism. Recognizing the risk factors for catheter-related thrombosis is extremely important to inform the development of catheter care guidelines. METHODS: Data were collected from a total of 1,532 patients who had undergone venous catheterization, including indwelling catheterization from 19 March 2019 to 30 March 2019 in the Sun Yat-sen Memorial Hospital. The factors for which data were to be collected included the patients' physical characteristics, catheter-related factors, and catheter care-related factors. Logistic regression analysis, the chi-squared test, Fisher's exact test, and the t-test were used to analyze the data. RESULTS: Of the 1,532 patients studied, 28 developed intraductal thrombi, and of the factors analyzed, malignancy, a catheterization history, a history of thrombophilia, surgery during the week before catheterization, the catheterization duration, and anticoagulant therapy were significant risk factors associated with catheter-related thrombosis (all p < 0.05). There were no significant associations between the catheter brand, the number of lumens, the insertion direction, or the factors associated with catheter care and catheter-related thrombosis (all p > 0.05). CONCLUSION: Our study incorporated clear and systematic risk factors associated with catheter-related thrombosis. Malignancy, history of thrombophilia, history of catheterization, surgery during the week before catheterization, and catheterization duration were associated with increased risks of catheter-related thrombosis. Prophylactic anticoagulation was effective for preventing and treating catheter-related thrombosis.

Electrically Responsive Shape Memory Composites Using Silver Plated Chopped Carbon Fiber.

High electrical and thermal conductivity are beneficial to the shape recovery performance of electroactive shape memory polymer composites. In this work, the chopped carbon fiber (CCF) was processed into silver plated chopped carbon fiber (Ag/CCF), and the Ag/CCF was filled into hydrogenated bisphenol A epoxy (H-EP) resin to fabricate the electro-induced shape memory polymer composites. The Ag/CCF/H-EP composites show good electrical and thermal conductivity compared to the CCF/H-EP composites. When the content of Ag/CCF reaches 1.8 wt%, the e Ag/CCF/H-EP composites reach the threshold of thermal conductivity, electrical conductivity and percolation. The thermal conductivity of H-EP composite with 5.4 wt% Ag/CCF is 2.33 W/(m·K), which is 2.6 times and 12 times of that of CCF/H-EP composite and H-EP matrix, respectively. When the content of Ag/CCF reaches 7.2 wt%, the volume resistivity of Ag/CCF/H-EP composites decrease from 1.69 × 1016 Ω·to 9.51 × 103 Ω cm, and surface resistivity from 6.91 × 1015 Ω to 6.19 × 102 Ω, respectively. And the Ag/CCF/H-EP composites show good mechanical properties and dynamic thermomechanical properties. When the content of Ag/CCF is more than 1.8 wt%, the Ag/CCF/H-EP composites exhibit excellent electroactive shape memory performance, and the shape recovery rate of the composites is more than 92%.

Quality assessment of licorice (Glycyrrhiza glabra L.) from different sources by multiple fingerprint profiles combined with quantitative analysis, antioxidant activity and chemometric methods.

Licorice, as a nutritional plant extensively used in food fields, grows in various origins of the world as wild and cultivated types. But existing methods were not adequate for quality estimation of licorice samples from multiple sources till date. In the present research, HPLC, UV and FT-IR were applied together to establish fingerprint profiles of licorice (Glycyrrhiza glabra L.) samples. Then, an appropriate quantitative method was adopted to evaluate their qualities. Furthermore, eight active chemical compositions and the potential antioxidant capacities of licorice samples were determined, and their intrinsic characteristics were excavated by chemometric methods. The results showed that the ingredient content and antioxidant capacity of licorice were closely related to the origin and growth type, and the established method was capable of accurately classifying wild and cultivated licorice samples from nine habitats into five quality grades. This study provides a novel and comprehensive strategy for food quality assessment.

Over-expression of Nav1.6 channels is associated with lymph node metastases in colorectal cancer.

BACKGROUND AND OBJECTIVES: Lymph node metastasis is a key factor in predicting and determining the prognosis of patients with colorectal cancer (CRC). Sodium channels are highly expressed in a variety of tumors and are closely related to tumor development, metastasis, and invasion. We investigated the relationship between the expressions of different subtypes of Nav channels and lymph node metastasis of CRC. METHODS: Real-time PCR (RT-qPCR) was carried out to measure the expressions of different sodium channel subtypes, chemokine receptors (CCR2, CCR4, CCR7), and lymphocyte infiltration-related biomarkers (CD3e, CD8a, IL-2RA) in CRC tissues from 97 patients. The expressions of Nav1.5 and Nav1.6 in surgically isolated lymph nodes were detected by immunohistochemistry. Correlation analysis between expressions of different genes and lymph node metastasis was performed by two-tailed t test. RESULTS: Nav1.1 and Nav1.6 were highly expressed in CRC tissues and positively correlated with CRC lymph node metastasis. Nav1.6 was also highly expressed in metastatic lymph nodes. Further analysis showed that the high expression of Nav1.6 was closely related to the one of CCR2\CCR4 in tumor lymph node metastasis. CONCLUSIONS: These results suggested that Nav1.6 might be a novel marker for CRC lymph node metastasis.

[Quality consistency evaluation of Fufanggancao tablets based on the control mode of standard preparation and quantitative fingerprint].

The control mode of standard preparation (SP) and quantitative high performance liquid chromatography (HPLC) fingerprint of Fufanggancao tablets (FFGCTs) combined with the quantification of five markers were successfully developed and applied to the precise and accurate assessment of the quality consistency of 145 FFGCTs from nine manufacturers. The profiling was determined by reversed-phase HPLC at 220 nm wavelength, where the reference fingerprint (RFP) of the FFGCTs reserved as standard preparation was established. Subsequently, the SP-RFP was considered as the evaluation standard, and a systematic quantitative fingerprint method was applied to the integrative quality discrimination of 145 batches of FFGCTs, from both qualitative and quantitative perspectives. Besides, the chromatographic systematic error of quantitative fingerprints was corrected by the double marker calibration method. The results showed that the qualities of the FFGCTs from the nine manufacturers were completely qualified. Moreover, all raw herb fingerprints and the simulated sample were determined by using the combined chromatographic conditions applied to the FFGCTs, which helped identify the source of the profiling peaks in the preparation and establish the correlation between the raw herb fingerprints and the preparation fingerprints. This eventually aided the intelligent prediction of the quality of the preparation or raw herbs and effective prevention of the inputs of inferior raw materials. In addition, we employed the ultraviolet full fingerprint dissolution method to differentiate the FFGCTs from five manufacturer dissolution, in which the rationality of the preparation process was evaluated. The method is feasible and accurate, and it can be applied to evaluate the quality and process technology consistency of FFGCTs. This paper provides a fundamental standard preparation evaluation mode and the basic operation procedure for the quality consistency assessment of traditional Chinese medicine.