A Genetically Encoded Fluorescent Sensor Enables Rapid and Specific Detection of Dopamine in Flies, Fish, and Mice.

Dopamine (DA) is a central monoamine neurotransmitter involved in many physiological and pathological processes. A longstanding yet largely unmet goal is to measure DA changes reliably and specifically with high spatiotemporal precision, particularly in animals executing complex behaviors. Here, we report the development of genetically encoded GPCR-activation-based-DA (GRABDA) sensors that enable these measurements. In response to extracellular DA, GRABDA sensors exhibit large fluorescence increases (ΔF/F0 ∼90%) with subcellular resolution, subsecond kinetics, nanomolar to submicromolar affinities, and excellent molecular specificity. GRABDA sensors can resolve a single-electrical-stimulus-evoked DA release in mouse brain slices and detect endogenous DA release in living flies, fish, and mice. In freely behaving mice, GRABDA sensors readily report optogenetically elicited nigrostriatal DA release and depict dynamic mesoaccumbens DA signaling during Pavlovian conditioning or during sexual behaviors. Thus, GRABDA sensors enable spatiotemporally precise measurements of DA dynamics in a variety of model organisms while exhibiting complex behaviors.

Coverage-sensitive mechanism of electrochemical NO reduction on the SrTiO3(001) surface: a DFT investigation.

Due to its adverse environmental and human health hazards, addressing the elimination of nitric oxide (NO) has become a pressing concern for modern society. Currently, electrochemical NO reduction provides a new alternative to traditional selective catalytic reduction technology under mild reaction conditions. However, the complexity and variability of products make the coverage of NO an influencing factor that needs to be investigated. Hence, this study delves into the coverage-sensitive mechanism of electrochemical NO reduction on cost-effective perovskite catalysts, using SrTiO3 as an example, through density functional theory calculations. Phase diagrams analysis reveals that the coverage range from 0.25 to 1.00 monolayer (ML) coverage is favorable for NO adsorption. Gibbs free energy results indicate that the selectivity is significantly influenced by NO coverage. NH3 is likely to be generated at low coverage, while N2O and N2 are more likely to be produced at high coverage through a dimer mechanism. Charge analysis suggests that the charge transfer and Ti-O bond strength between reactants and catalysts are crucial factors. This work not only provides deep insights into coverage-sensitive reaction mechanisms but also is a guideline towards further rational design of high-performance perovskite catalysts.

Dynamic functional connectivity MEG features of Alzheimer's disease.

Dynamic resting state functional connectivity (RSFC) characterizes time-varying fluctuations of functional brain network activity. While many studies have investigated static functional connectivity, it has been unclear whether features of dynamic functional connectivity are associated with neurodegenerative diseases. Popular sliding-window and clustering methods for extracting dynamic RSFC have various limitations that prevent extracting reliable features to address this question. Here, we use a novel and robust time-varying dynamic network (TVDN) approach to extract the dynamic RSFC features from high resolution magnetoencephalography (MEG) data of participants with Alzheimer's disease (AD) and matched controls. The TVDN algorithm automatically and adaptively learns the low-dimensional spatiotemporal manifold of dynamic RSFC and detects dynamic state transitions in data. We show that amongst all the functional features we investigated, the dynamic manifold features are the most predictive of AD. These include: the temporal complexity of the brain network, given by the number of state transitions and their dwell times, and the spatial complexity of the brain network, given by the number of eigenmodes. These dynamic features have higher sensitivity and specificity in distinguishing AD from healthy subjects than the existing benchmarks do. Intriguingly, we found that AD patients generally have higher spatial complexity but lower temporal complexity compared with healthy controls. We also show that graph theoretic metrics of dynamic component of TVDN are significantly different in AD versus controls, while static graph metrics are not statistically different. These results indicate that dynamic RSFC features are impacted in neurodegenerative disease like Alzheimer's disease, and may be crucial to understanding the pathophysiological trajectory of these diseases.

Integrated transcriptomic and proteomic analyses of two sugarcane (Saccharum officinarum Linn.) varieties differing in their lodging tolerance.

BACKGROUND: Lodging seriously affects sugarcane stem growth and sugar accumulation, reduces sugarcane yield and sucrose content, and impedes mechanization. However, the molecular mechanisms underlying sugarcane lodging tolerance remain unclear. In this study, comprehensive transcriptomic and proteomic analyses were performed to explore the differential genetic regulatory mechanisms between upright (GT42) and lodged (GF98-296) sugarcane varieties. RESULTS: The stain test showed that GT42 had more lignin and vascular bundles in the stem than GF98-296. The gene expression analysis revealed that the genes that were differentially expressed between the two varieties were mainly involved in the phenylpropanoid pathway at the growth stage. The protein expression analysis indicated that the proteins that were differentially expressed between the two varieties were related to the synthesis of secondary metabolites, the process of endocytosis, and the formation of aminoacyl-tRNA. Time-series analysis revealed variations in differential gene expression patterns between the two varieties, whereas significant protein expression trends in the two varieties were largely consistent, except for one profile. The expression of CYP84A, 4CL, and CAD from the key phenylpropanoid biosynthetic pathway was enhanced in GT42 at stage 2 but suppressed in GF98-296 at the growth stage. Furthermore, the expression of SDT1 in the nicotinate and nicotinamide metabolism was enhanced in GT42 cells but suppressed in GF98-296 cells at the growth stage. CONCLUSION: Our findings provide reference data for mining lodging tolerance-related genes that are expected to facilitate the selective breeding of sugarcane varieties with excellent lodging tolerance.

High-Activity Fe3 C as pH-Universal Electrocatalyst for Boosting Oxygen Reduction Reaction and Zinc-Air Battery.

Transition metal catalysts are regarded as one of promising alternatives to replace traditional Pt-based catalysts for oxygen reduction reaction (ORR). In this work, an efficient ORR catalyst is synthesized by confining Fe3 C nanoparticles into N, S co-doped porous carbon nanosheets (Fe3 C/N,S-CNS) via high-temperature pyrolysis, in which 5-sulfosalicylic acid (SSA) demonstrates as an ideal complexing agent for iron (ΙΙΙ) acetylacetonate while g-C3 N4 behaves as a nitrogen source. The influence of the pyrolysis temperature on the ORR performance is strictly examined in the controlled experiments. The obtained catalyst exhibits excellent ORR performance (E1/2  = 0.86 V; Eonset  = 0.98 V) in alkaline electrolyte, coupled by exhibiting the superior catalytic activity and stability (E1/2  = 0.83 V, Eonset  = 0.95 V) to Pt/C in acidic media. In parallel, its ORR mechanism is carefully illustrated by the density functional theory (DFT) calculations, especially the role of the incorporated Fe3 C played in the catalytic process. The catalyst-assembled Zn-air battery also exhibits a much higher power density (163 mW cm-2 ) and ultralong cyclic stability in the charge-discharge test for 750 h with a gap increase down to 20 mV. This study provides some constructive insights for preparation of advanced ORR catalysts in green energy conversion units correlated systems.

Low awareness of venous thromboembolism among neurosurgical hospitalized patients: a cross-sectional study.

BACKGROUND: Venous thromboembolism (VTE) including Deep Venous Thrombosis (DVT) and Pulmonary Embolism (PE), is a serious cause of patient morbidity and mortality in hospitals. Neurosurgical hospitalized patients have higher rates of immobility and bed rest, thus increasing their risk of developing VTE. This highlights the need for their thromboprophylaxis regimens. Patients' awareness of VTE is essential for promoting strategies such as early ambulation and encouraging self-assessment and self-reporting of VTE signs and symptoms. This study evaluated neurosurgical hospitalized patients' awareness of VTE and explored the influencing factors to provide a theoretical basis for nursing intervention. METHODS: We selected one tertiary level hospital in Hunan Province and randomly sampled eligible patients from each five neurosurgical units. We conducted a cross-sectional survey of the hospitalized patients of neurosurgery using the self-designed and validated VTE knowledge questionnaire, and the influencing factors were analyzed using SPSS 26.0. RESULTS: A total of 386 neurosurgical hospitalized patients completed the survey. The score of VTE knowledge in neurosurgical hospitalized patients was 13.22 (SD = 11.52). 36.0% and 21.2% of participants reported they had heard of DVT and PE, respectively. 38.9% of participants were unable to correctly identify any symptoms of VTE. The most frequently identified risk factor was 'immobility or bed rest for more than three days' (50.0% of participants), and 38.1% of patients agreed that PE could cause death. 29.5% of participants were unable to identify any prophylactic measures of VTE. The results of Negative Binomial Regression showed that the influencing factors of VTE knowledge in neurosurgical hospitalized patients were education level (P < 0.004) and sources of information related to VTE, including nurses (95% CI = 2.201-4.374, P < 0.001), and family member/friend (95% CI = 2.038-4.331, P < 0.001), Internet/TV (95% CI = 1.382-2.834, P < 0.001). Other sources included patient /pamphlet/poster /professional books (95% CI = 1.492-3.350, P < 0.001). CONCLUSIONS: This study demonstrates the lack of awareness of VTE among neurosurgical hospitalized patients. More attention must be paid to carrying out training on VTE knowledge according to different characteristics of neurosurgical hospitalized patients, so as to ensure safe and high-quality patient care.

Knowledge, attitude, and practice of pediatric nurses in prevention of central venous access device-related thrombosis in hospitalized children: a nationwide cross-sectional survey.

Central venous access device-related thrombosis (CRT) is a common complication in hospitalized children. The pediatric nurses' knowledge, attitude, and practice are of great significance for CRT prevention in hospitalized children. The purpose of this study was to elaborate on the level and influencing factors of pediatric nurses' knowledge, attitude, and practice on the prevention related to CRT in hospitalized children. This national cross-sectional study was carried out in China from January 16, 2021, to April 23, 2021. A multi-stage sampling method was adopted, and 1060 pediatric nurses from 21 hospitals participated in this study. The current situation and influencing factors of pediatric nurses' knowledge, attitude, and practice were investigated by descriptive statistics, approximate t test or independent-sample t test, nonparametric Kruskal-Wallis H test, one-way analysis of variance, and multiple linear regression analysis. The relationship among pediatric nurses' knowledge, attitude, and practice was explored by the Pearson correlation analysis. Among all pediatric nurses involved in this study, 25% had insufficient knowledge, 18% had negative attitudes, and 24% had poor behaviors. The main influencing factors on the knowledge, attitude, and practice included the highest education level of pediatric nurses (ß = 0.10, P = .001), whether received training related to CRT prevention (ß = 0.09-0.14, P < .01), whether CRT-related knowledge was enough for dealing with clinical work (ß = 0.18-0.21, P < .001), and the importance of hospitals/departments on children CRT prevention (ß = 0.16-0.24, P < .001). There was a positive correlation between knowledge, attitude, and practice (r = 0.24-0.77, P < .01).    Conclusion: Pediatric nurses' CRT-prevention knowledge and practice are unsatisfactory, while their preventive attitude toward CRT prevention is optimistic. This study assists the formulation of comprehensive intervention strategies for pediatric nurses in preventing CRT in hospitalized children by hospital-related organizations and nursing managers, so as to improve the participation of pediatric nurses in CRT prevention and reduce the occurrence of CRT for hospitalized children. What is Known: • As a common complication in hospitalized children, CRT can induce many potentially serious complications. • A professional nursing team is an important prerequisite for reducing CRT incidence. What is New: • The levels of pediatric nurses' knowledge and practice are not satisfactory, while pediatric nurses' preventive attitude toward CRT prevention is optimistic. • Hospital-related organizations and nursing managers should highlight the importance of CRT prevention and encourage pediatric nurses to improve their expertise and strengthen the training related to CRT prevention.

Development and validation of a nomogram model for central venous access device-related thrombosis in hospitalized children.

This study aimed to develop and validate a nomogram model of central venous access device-related thrombosis (CRT) for hospitalized children. A total of 503 consecutive cases from a hospital in Changsha City, Hunan Province were stochastically classified into the training set and internal validation set at a ratio of 7:3, and 85 consecutive cases in two hospitals in Urumqi City, Xinjiang Uygur Autonomous Region were collected as an external validation set. Univariate analysis and multivariate analysis on CRT-related risk factors of hospitalized children were conducted, a logistic regression model was employed to establish the nomogram, and the discrimination, calibration, and decision curve analysis was performed to assess the proposed nomogram model. The nomogram model involved seven independent risk factors, including blind catheterization, abnormal liver function, central line-associated bloodstream infection, infection, number of catheter lines, leukemia, and bed rest > 72 h. The discrimination results showed that the area under the receiver operating characteristic curve of the training set, internal validation set, and external validation set was 0.74, 0.71, and 0.76 respectively, and the accuracy rates of the proposed nomogram model were 79%, 72%, and 71% in the training set, internal validation set, and external validation set. The calibration results also showed that the calibration curve had great fitness for each dataset. More importantly, the decision curve suggested that the proposed nomogram model had a prominent clinical significance. CONCLUSION: The nomogram model can be used as a risk assessment tool to reduce the missed diagnosis rate and the incidence of CRT in hospitalized children. WHAT IS KNOWN: • Central venous access device-related thrombosis is generally asymptomatic for hospitalized children, causing the missed diagnosis of central venous access device-related thrombosis easily. • No risk prediction nomogram model for central venous access device-related thrombosis in hospitalized children has been established. WHAT IS NEW: • A visual and personalized nomogram model was built by seven accessible variables (blind catheterization, abnormal liver function, central line-associated bloodstream infection, infection, number of catheter lines, leukemia, and bed rest > 72 h). • The model can effectively predict the risk of central venous access device-related thrombosis for hospitalized children.

Empirical Bayesian localization of event-related time-frequency neural activity dynamics.

Accurate reconstruction of the spatio-temporal dynamics of event-related cortical oscillations across human brain regions is an important problem in functional brain imaging and human cognitive neuroscience with magnetoencephalography (MEG) and electroencephalography (EEG). The problem is challenging not only in terms of localization of complex source configurations from sensor measurements with unknown noise and interference but also for reconstruction of transient event-related time-frequency dynamics of cortical oscillations. We recently proposed a robust empirical Bayesian algorithm for simultaneous reconstruction of complex brain source activity and noise covariance, in the context of evoked and resting-state data. In this paper, we expand upon this empirical Bayesian framework for optimal reconstruction of event-related time-frequency dynamics of regional cortical oscillations, referred to as time-frequency Champagne (TFC). This framework enables imaging of five-dimensional (space, time, and frequency) event-related brain activity from M/EEG data, and can be viewed as a time-frequency optimized adaptive Bayesian beamformer. We evaluate TFC in both simulations and several real datasets, with comparisons to benchmark standards - variants of time-frequency optimized adaptive beamformers (TFBF) as well as the sLORETA algorithm. In simulations, we demonstrate several advantages in estimating time-frequency cortical oscillatory dynamics compared to benchmarks. With real MEG data, we demonstrate across many datasets that the proposed approach is robust to highly correlated brain activity and low SNR data, and is able to accurately reconstruct cortical dynamics with data from just a few epochs.

Time-varying dynamic network model for dynamic resting state functional connectivity in fMRI and MEG imaging.

Dynamic resting state functional connectivity (RSFC) characterizes fluctuations that occur over time in functional brain networks. Existing methods to extract dynamic RSFCs, such as sliding-window and clustering methods that are inherently non-adaptive, have various limitations such as high-dimensionality, an inability to reconstruct brain signals, insufficiency of data for reliable estimation, insensitivity to rapid changes in dynamics, and a lack of generalizability across multiply functional imaging modalities. To overcome these deficiencies, we develop a novel and unifying time-varying dynamic network (TVDN) framework for examining dynamic resting state functional connectivity. TVDN includes a generative model that describes the relation between a low-dimensional dynamic RSFC and the brain signals, and an inference algorithm that automatically and adaptively learns the low-dimensional manifold of dynamic RSFC and detects dynamic state transitions in data. TVDN is applicable to multiple modalities of functional neuroimaging such as fMRI and MEG/EEG. The estimated low-dimensional dynamic RSFCs manifold directly links to the frequency content of brain signals. Hence we can evaluate TVDN performance by examining whether learnt features can reconstruct observed brain signals. We conduct comprehensive simulations to evaluate TVDN under hypothetical settings. We then demonstrate the application of TVDN with real fMRI and MEG data, and compare the results with existing benchmarks. Results demonstrate that TVDN is able to correctly capture the dynamics of brain activity and more robustly detect brain state switching both in resting state fMRI and MEG data.

Theoretical understanding on all-solid frustrated Lewis pair sites of C2N anchored by single metal atom.

The design of all-solid heterogeneous catalysts with frustrated Lewis pairs (FLPs) has attracted much attention recently because of their appealing low dissociation energy for H2 molecules due to which a promotion of hydrogenation reaction is expected. The sterically encumbered Lewis acid (metal site) and base (nitrogen site) in the cavity of single transition metal atom-doped M/C2N sheets make them potential candidates for the design of catalysts with FLPs, while a comprehensive understanding of their intrinsic property and reactivity is still lacking. Calculations show that the complete dissociation of the H2 molecule into two H* states at the N sites requires two steps: heterolytic cleavage of the H2 molecule and the transfer of H* from the metal site to the N site, which are strongly related to the acidity of the metal site. Ni/C2N and Pd/C2N, which outperform the other eight transition metal atom (M) anchored M/C2N candidates, possess low energy barriers for the complete dissociation of H2 molecules, with values of only 0.30 and 0.20 eV, respectively. Furthermore, both Ni/C2N and Pd/C2N catalysts can achieve semi-hydrogenation of C2H2 into C2H4, with overall barriers of 0.81 and 0.75 eV, respectively, which are lower than those reported for many other catalysts. It is speculated that M/C2N catalysts with intrinsic FLPs may also find applications in other important hydrogenation reactions.

Cold-Induced Physiological and Biochemical Alternations and Proteomic Insight into the Response of Saccharum spontaneum to Low Temperature.

Sugarcane, a cash crop, is easily affected by low temperature, which results in a decrease in yield and sugar production. Breeding a new variety with cold tolerance is an essential strategy to reduce loss from cold stress. The identification of germplasms and genes/proteins with cold tolerance is a vital step in breeding sugarcane varieties with cold tolerance via a conventional program and molecular technology. In this study, the physiological and biochemical indices of 22 genotypes of S. spontaneum were measured, and the membership function analysis method was used to comprehensively evaluate the cold tolerance ability of these genotypes. The physiological and biochemical indices of these S. spontaneum genotypes showed a sophisticated response to low temperature. On the basis of the physiological and chemical indices, the genotypes were classified into different cold tolerance groups. Then, the high-tolerance genotype 1027 and the low-tolerance genotype 3217 were selected for DIA-based proteomic analysis by subjecting them to low temperature. From the four comparison groups, 1123, 1341, 751, and 1693 differentially abundant proteins (DAPs) were identified, respectively. The DAPs based on genotypes or treatments participated in distinct metabolic pathways. Through detailed analysis of the DAPs, some proteins related to protein homeostasis, carbohydrate and energy metabolism, amino acid transport and metabolism, signal transduction, and the cytoskeleton may be involved in sugarcane tolerance to cold stress. Furthermore, five important proteins related to cold tolerance were discovered for the first time in this study. This work not only provides the germplasms and candidate target proteins for breeding sugarcane varieties with cold tolerance via a conventional program and molecular breeding, but also helps to accelerate the determination of the molecular mechanism underlying cold tolerance in sugarcane.

Association between anion gap and mortality of aortic aneurysm in intensive care unit after open surgery.

BACKGROUND: There has not been a well-accepted prognostic model to predict the mortality of aortic aneurysm patients in intensive care unit after open surgery repair. Otherwise, our previous study found that anion gap was a prognosis factor for aortic aneurysm patients. Therefore, we wanted to investigate the relationship between anion gap and mortality of aortic aneurysm patients in intensive care unit after open surgery repair. METHODS: From Medical Information Mart for Intensive Care III, data of aortic aneurysm patients in intensive care unit after open surgery were enrolled. The primary clinical outcome was defined as death in intensive care unit. Univariate analysis was conducted to compare the baseline data in different groups stratified by clinical outcome or by anion gap level. Restricted cubic spline was drawn to find out the association between anion gap level and mortality. Subgroup analysis was then conducted to show the association in different level and was presented as frost plot. Multivariate regression models were built based on anion gap and were adjusted by admission information, severity score, complication, operation and laboratory indicators. Receiver operating characteristic curves were drawn to compare the prognosis ability of anion gap and simplified acute physiology score II. Decision curve analysis was finally conducted to indicate the net benefit of the models. RESULTS: A total of 405 aortic aneurysm patients were enrolled in this study and the in-intensive-care-unit (in-ICU) mortality was 6.9%. Univariate analysis showed that elevated anion gap was associated with high mortality (P value < 0.001), and restricted cubic spline analysis showed the positive correlation between anion gap and mortality. Receiver operating characteristic curve showed that the mortality predictive ability of anion gap approached that of simplified acute physiology score II and even performed better in predicting in-hospital mortality (P value < 0.05). Moreover, models based on anion gap showed that 1 mEq/L increase of anion gap improved up to 42.3% (95% confidence interval 28.5-59.8%) risk of death. CONCLUSIONS: The level of serum anion gap was an important prognosis factor for aortic aneurysm mortality in intensive care unit after open surgery.

Single and double boron atoms doped nanoporous C2N-h2D electrocatalysts for highly efficient N2 reduction reaction: a density functional theory study.

The electrocatalytical process is the most efficient way to produce ammonia (NH3) under ambient conditions, but developing a highly efficient and low-cost metal-free electrocatalysts remains a major scientific challenge. Hence, single atom and double boron (B) atoms doped 2D graphene-like carbon nitride (C2N-h2D) electrocatalysts have been designed (B@C2N and B2@C2N), and the efficiency of N2 reduction reaction (NRR) is examined by density functional theory calculation. The results show that the single and double B atoms can both be strongly embedded in natural nanoporous C2N with superior catalytic activity for N2 activation. The reaction mechanisms of NRR on the B@C2N and B2@C2N are both following an enzymatic pathway, and B2@C2N is a more efficient electrocatalyst with extremely low overpotential of 0.19 eV comparing to B@C2N (0.29 eV). In the low energy region, the hydrogenation of N2 is thermodynamically more favorable than the hydrogen production, thereby improving the selectivity for NRR. Based on these results, a new double-atom strategy may help guiding the experimental synthesis of highly efficient NRR electrocatalysts.

Comparative transcriptome profiling of resistant and susceptible sugarcane genotypes in response to the airborne pathogen Fusarium verticillioides.

Fusarium verticillioides is the pathogen associated with pokkah boeng disease (PBD), the most significant airborne disease of sugarcane. The molecular mechanisms that regulate the defense responses of sugarcane towards this fungus are not yet fully known. Samples of 'YT 94/128' (resistant, R) and 'GT 37' (susceptible, S) inoculated with F. verticillioides on the 14 days post-inoculation were used to analyze the transcriptome to screen R genes. In total, 80.93 Gb of data and 76,175 Unigenes were obtained after assembling the sequencing data, and comparisons of Unigenes with NR, Swiss-prot, KOG, and KEGG databases confirmed 42,451 Unigenes. The analysis of differentially expression genes (DEGs) in each sample revealed 9092 DEGs in 'YT 94/128,' including 8131 up-regulated DEGs and 961 down-regulated DEGs; there were 9829 DEGs in 'GT 37,' including 7552 up-regulated DEGs and 2277 down-regulated DEGs. The identified DEGs were mainly involved in catalytic enzyme activity, cell protease, hydrolytic enzymes, peptide enzyme, protein metabolism process of negative regulation, phenylpropanoid metabolism, extracellular region, aldehyde dehydrogenase, endopeptidase, REDOX enzyme, protein kinases, and phosphoric acid transferase categories. KEGG pathway clustering analysis showed that the DEGs involved in resistance were significantly related to metabolic pathways of phenylpropanoid biosynthesis, cutin, suberine and wax biosynthesis, nitrogenous metabolism, biosynthesis of secondary metabolites, and plant-pathogen interactions. This application of transcriptomic data clarifies the mechanism of interactions between sugarcane and F. verticillioides, which can help to reveal disease-related metabolic pathways, molecular regulatory networks, and key genes involved in sugarcane responses to F. verticillioides.

Raoultella sp. strain L03 fixes N2 in association with micropropagated sugarcane plants.

N2 -fixing bacteria belonging to the genus Raoultella of the family Enterobacteriaceae are widely associated with plants. Raoultella sp. strain L03 was isolated from surface-sterilized sugarcane roots. In this study, we inoculated the strain L03 to microbe-free micropropagated plantlets of the main sugarcane cultivar ROC22 grown in Guangxi, China and determined N2 -fixation and association between strain L03 and sugarcane plants. Inoculation of strain L03 increased plant biomass, total N, N concentration and chlorophyll, and relieved N-deficiency symptoms of plants under an N-limiting condition. An (15) N isotope dilution assay revealed (15) N isotope dilution in the inoculated sugarcane plants and incorporation of the fixed (14) N from air into chlorophyll. Moreover, a gfp-tagged and antibiotic-resistant L03 strain was reisolated from surface-sterilized sugarcane plants and was detected in plant tissues by fluorescent microscopy. This study for the first time demonstrates that a Raoultella bacterium is able to fix N2 in association with the plant host.

Controllable Construction of a Mo2C/MoO2 Interface with an Ideal Mo2C/MoO2 Ratio for Efficient Electrocatalytic Nitrogen Reduction to Ammonia.

Electrocatalytic nitrogen reduction reaction (NRR) is considered to be a viable contender for the production of NH3. However, due to the sluggish adsorption and activation of the electrocatalyst toward inert N2 molecules, there is an urgent need for developing effective catalysts to facilitate the reaction. Inspired by natural nitrogenase, in which Mo atoms are the active centers, Mo-based electrocatalysts have received considerable attention, but further exploration is still necessary. Interface-engineered electrocatalysts can effectively optimize the absorption and activation of the catalytic active center for N2 and thus improve the electrocatalytic activity of NRR. However, the lack of studies for controllably constructing an optimal ratio of two phases at the interface hinders the development of NRR electrocatalysts. Herein, a series of Mo2C/MoO2 interface-engineered electrocatalysts with various Mo2C/MoO2 ratios were constructed by controlling the Y dosages. The controlled experimental results verified that the catalytic activity of NRR, the dosage of Y, and the ratio of Mo2C/MoO2 were strongly correlated. Density functional theory calculations show that the C-Mo-O coordination at the Mo2C/MoO2 interface can optimize the reaction path and reduce the energy barrier of the reaction intermediates, thereby enhancing the reaction kinetics of NRR.

Bioelectrochemically altering microbial ecology in upflow anaerobic sludge blanket to enhance methanogenesis fed with high-sulfate methanolic wastewater.

A bioelectrochemical upflow anaerobic sludge blanket (BE-UASB) was constructed and compared with the traditional UASB to investigate the role of bioelectrocatalysis in modulating methanogenesis and sulfidogensis involved within anaerobic treatment of high-sulfate methanolic wastewater (COD/SO42- ratio ≤ 2). Methane production rate for BE-UASB was 1.4 times higher than that of the single UASB, while SO42- removal stabilized at 16.7 %. Bioelectrocatalysis selectively enriched key functional anaerobes and stimulated the secretion of extracellular polymeric substances, especially humic acids favoring electron transfer, thereby accelerating the electroactive biofilms development of electrodes. Methanomethylovorans was the dominant genus (35 %) to directly convert methanol to CH4. Methanobacterium as CO2 electroreduction methane-producing archaea appeared only on electrodes. Acetobacterium exhibited anode-dependence, which provided acetate for sulfate-reducing bacteria (norank Syntrophobacteraceae and Desulfomicrobium) through synergistic coexistence. This study confirmed that BE-UASB regulated the microbial ecology to achieve efficient removal and energy recovery of high-sulfate methanolic wastewater.

Biogas upgrading and membrane anti-fouling mechanisms in electrochemical anaerobic membrane bioreactor (EC-AnMBR): Focusing on spatio-temporal distribution of metabolic functionality of microorganisms.

Electrochemical anaerobic membrane bioreactor (EC-AnMBR) by integrating a composite anodic membrane (CAM), represents an effective method for promoting methanogenic performance and mitigating membrane fouling. However, the development and formation of electroactive biofilm on CAM, and the spatio-temporal distribution of key functional microorganisms, especially the degradation mechanism of organic pollutants in metabolic pathways were not well documented. In this work, two AnMBR systems (EC-AnMBR and traditional AnMBR) were constructed and operated to identify the role of CAM in metabolic pathway on biogas upgrading and mitigation of membrane fouling. The methane yield of EC-AnMBR at HRT of 20 days was 217.1 ± 25.6 mL-CH4/g COD, about 32.1 % higher compared to the traditional AnMBR. The 16S rRNA analysis revealed that the EC-AnMBR significantly promoted the growth of hydrolysis bacteria (Lactobacillus and SJA-15) and methanogenic archaea (Methanosaeta and Methanobacterium). Metagenomic analysis revealed that the EC-AnMBR promotes the upregulation of functional genes involved in carbohydrate metabolism (gap and kor) and methane metabolism (mtr, mcr, and hdr), improving the degradation of soluble microbial products (SMPs)/extracellular polymeric substances (EPS) on the CAM and enhancing the methanogens activity on the cathode. Moreover, CAM biofilm exhibits heterogeneity in the degradation of organic pollutants along its vertical depth. The bacteria with high hydrolyzing ability accumulated in the upper part, driving the feedstock degradation for higher starch, sucrose and galactose metabolism. A three-dimensional mesh-like cake structure with larger pores was formed as a biofilter in the middle and lower part of CAM, where the electroactive Geobacter sulfurreducens had high capabilities to directly store and transfer electrons for the degradation of organic pollutants. This outcome will further contribute to the comprehension of the metabolic mechanisms of CAM module on membrane fouling control and organic solid waste treatment and disposal.

Enhanced dewaterability and triclosan removal of waste activated sludge with iron-rich mineral-activated peroxymonosulfate.

High water and pharmaceutical and care products (PPCPs) bounded in sludge flocs limit its utilization and disposal. The advanced oxidation process of perxymonosulfate (PMS) catalyzed by iron salts has been widely used in sludge conditioning. In this study, two iron-rich minerals pyrite and siderite were proposed to enhance sludge dewatering performance and remove the target contaminant of triclosan (TCS). The permanent release of Fe2+ in the activation of PMS made siderite more effective in enhancing sludge dewater with capillary suction time (CST) diminishing by 60.5 %, specific resistance to filtration (SRF) decreasing by 79.2 %, and bound water content (BWC) dropping from 37.1 % to 2.6 % at siderite/PMS dosages of 0.36/0.20 mmol/g-TSS after 20 min of pretreatment. Pyrite/PMS performed slightly inferior under the same conditions and the corresponding CST and SRF decreased by 51.5 % and 71.8 % while the BWC only declined to 17.8 %. Rheological characterization was employed to elucidate the changes in sludge dewatering performance, with siderite/PMS treated sludge showing a 48.3 % reduction in thixotropy, higher than 28.4 % of pyrite/PMS. Oscillation and creep tests further demonstrated the significantly weakened viscoelastic behavior of the sludge by siderite/PMS pretreatment. For TCS mineralization removal, siderite/PMS achieved a high removal efficiency of 43.9 %, in comparison with 39.9 % for pyrite/PMS. The reduction in the sludge solids phase contributed the most to the TCS removal. Free radical quenching assays and EPR spectroscopy showed that both siderite/PMS and pyrite/PMS produced SO4-·  and ·OH, with the latter acting as the major radicals. Besides, the dosage of free radicals generated from siderite/PMS exhibited a lower time-dependence, which also allowed it to outperform in destroying EPS matrix, neutralizing the negative Zeta potential of sludge flocs, and mineralizing macromolecular organic matter.