Regulation Strategies for Fe-N-C and Co-N-C Catalysts for the Oxygen Reduction Reaction.

Proton exchange membrane fuel cells (PEMFCs) and alkaline membrane fuel cells (AEMFCs) have received great attention as energy devices of the next generation. Accelerating oxygen reduction reaction (ORR) kinetics is the key to improve PEMFC and AEMFC performance. Platinum-based catalysts are the most widely used catalysts for the ORR, but their high price and low abundance limit the commercialization of fuel cells. Non-noble metal-nitrogen-carbon (M-N-C) is considered to be the most likely material class to replace Pt-based catalysts, among which Fe-N-C and Co-N-C have been widely studied due to their excellent intrinsic ORR performance and have made great progress in the past decades. With the improvement of synthesis technology and a deeper understanding of the ORR mechanism, some reported Fe-N-C and Co-N-C catalysts have shown excellent ORR activity close to that of commercial Pt/C catalysts. Inspired by the progress, regulation strategies for Fe-N-C and Co-N-C catalysts are summarized in this Review from 5 perspectives: (1) coordinated atoms, (2) environmental heteroatoms and defects, (3) dual-metal active sites, (4) metal-based particle promoters, and (5) curved carbon layers. We also make suggestions on some challenges facing Fe-N-C and Co-N-C research.

Nicotine metabolism pathway in bacteria: mechanism, modification, and application.

Nicotine is a harmful pollutant mainly from the waste of tobacco factories. It is necessary to remove nicotine via high efficient strategies such as bioremediation. So far, an increasing number of nicotine degrading strains have been isolated. However, their degrading efficiency and tolerance to high content nicotine is still not high enough for application in real environment. Thus, the modification of nicotine metabolism pathway is obligated and requires comprehensive molecular insights into whole cell metabolism of nicotine degrading strains. Obviously, the development of multi-omics technology has accelerated the mechanism study on microbial degradation of nicotine and supplied more novel strategy of strains modification. So far, three pathways of nicotine degradation, pyridine pathway, pyrrolidine pathway, and the variant of pyridine and pyrrolidine pathway (VPP pathway), have been clearly identified in bacteria. Muti-omics analysis further revealed specific genome architecture, regulation mechanism, and specific genes or enzymes of three pathways, in different strains. Especially, muti-omics analysis revealed that functional modules coexisted in different genome loci and played additional roles on enhanced degradation efficiency in bacteria. Based on the above discovery, genomic editing strategy becomes more feasible to greatly improve bacterial degrading efficiency of nicotine.

Review of casualties and losses of UK fishing vessels from 2013 to 2020.

This study analyses the relationship between vessel groups (small, medium and large) and casualty or loss type of UK fishing vehicles based on a summary of information concerning casualties and losses that occurred on fishing vessels in the UK from 2013 to 2020. The study establishes loss of control as the main cause of casualty occurrences for all fishing vessels. Further, flooding/foundering is the main contributor to the loss of fishing vessels smaller than 24 m in length, and grounding/stranding is the main contributor to the loss of fishing vessels 24 m or longer. Fishing vessels below 15 m in length comprise the majority of casualties and losses, while medium-size vessels (15 m or longer, but less than 24 m) make the highest average contribution per vessel to casualties.

Associations between tobacco inhalation and semen parameters in men with primary and secondary infertility: a cross-sectional study.

Objective: To examine the impact of tobacco smoking on seminal parameters in men with both primary and secondary infertility. Methods: This cross-sectional study analyzed 1938 infertile men from China who were categorized as nonsmokers (n=1,067) and smokers (n=871), with the latter group further divided into moderate smokers (1-10 cigarettes per day) (n=568) and heavy smokers (>10 cigarettes per day) (n=303). We assessed semen volume, concentration, total sperm count, progressive motility, and normal morphology following World Health Organization (WHO 2010) guidelines. A logistic regression model was used to analyze the relationships between smoking and seminal parameters while also controlling for lifestyle factors. Results: The analysis demonstrated a statistically significant correlation between smoking and adverse seminal parameters in both primary and secondary infertility patients. Specifically, primary infertile men who smoked had a lower semen concentration, with heavy smokers showing a median sperm concentration of 59.2×10^6/ml compared to 68.6×10^6/ml in nonsmokers (P=0.01). The secondary infertile men who smoked exhibited reduced forward sperm motility, with heavy smokers demonstrating a median progressive motility of 44.7%, which was significantly lower than the 48.1% observed in nonsmokers (P=0.04). Conclusion: Smoking is significantly associated with detrimental effects on seminal parameters in infertile men, thus highlighting the need for cessation programs as part of fertility treatment protocols. Encouraging smoking cessation could substantially improve semen quality and fertility outcomes in this population.

Effect of leukocytes on semen quality in men from primary and secondary infertile couples: A cross-sectional study.

Background and Aims: Leukocytospermia (LCS) is a known cause of male infertility. However, the relationship between seminal leukocytes and semen quality among infertile couples remains controversial. This study aims to investigate the association between semen quality and LCS in male partners of infertile couples. Methods: Semen samples were collected from 512 men who asked for a fertility evaluation in a reproductive center in China. Seminal leukocytes were counted following peroxidase staining with benzidine. Other semen parameters were compared in subfertile men with and without LCS. Results: Poor semen quality (e.g., low semen volume, sperm concentration, and sperm progressive/total motility) was observed among men with LCS compared to those without LCS. Men with LCS had a higher risk of low sperm progressive motility (OR = 0.99, 95% CI = 0.98-0.99, p = 0.02) and total motility (OR = 0.99, 95% CI = 0.98-0.99, p = 0.02), even after adjustment for potential confounders (both OR = 0.99, 95% CI = 0.98-0.99, p = 0.03). Lower sperm viability was observed in LCS from male partners of secondary couples, while no significant difference in semen parameters was found between men with and without LCS in male partners of primary infertile couples. Low sperm motility and viability were associated with LCS in men from secondary infertile couples after adjusting for confounders (OR = 0.97, 95% CI = 0.95-0.99, p = 0.04; OR = 0.94, 95% CI = 0.89-0.99, p = 0.04, respectively). Conclusions: Our findings indicate that a higher risk of abnormal semen parameters was correlated with an increased number of leukocytes in men from secondary infertile couples.

Function Enhancement of a Metabolic Module via Endogenous Promoter Replacement for Pseudomonas sp. JY-Q to Degrade Nicotine in Tobacco Waste Treatment.

Nicotine-degrading Pseudomonas sp. JY-Q is a preferred strain utilized in reconstituted tobacco process for tobacco waste treatment. However, its efficiency of nicotine metabolism still requires to be improved via genomic technology such as promoter engineering based on genomic information. Concerning upstream module of nicotine metabolic pathway, we found that two homologous genes of nicotine dehydrogenase (nicA2 and nox) coexisted in strain JY-Q. However, the transcriptional amount of nox was 20-fold higher than that of nicA2. Thus, the nicA2 expression required improvement. Combinatorial displacement was accomplished for two predicted endogenous promoters, named as PnicA2 and Pnox for nicA2 and nox, respectively. The mutant with Pnox as the promoters for both nicA2 and nox exhibited the best nicotine metabolic capacity which increased by 66% compared to the wild type. These results suggested that endogenous promoter replacement is also feasible for function improvement of metabolic modules and strain enhancement of biodegradation capacity to meet real environment demand.

Enzyme cascade-amplified immunoassay based on the nanobody-alkaline phosphatase fusion and MnO2 nanosheets for the detection of ochratoxin A in coffee.

Ochratoxin A (OTA) is a common food contaminant with multiple toxicities and thus rapid and accurate detection of OTA is indispensable to minimize the threat of OTA to public health. Herein a novel enzyme cascade-amplified immunoassay (ECAIA) based on the mutated nanobody-alkaline phosphatase fusion (mNb-AP) and MnO2 nanosheets was established for detecting OTA in coffee. The detection principle is that the dual functional mNb-AP could specifically recognize OTA and dephosphorylate the ascorbic acid-2-phosphate (AAP) into ascorbic acid (AA), and the MnO2 nanosheets mimicking the oxidase could be reduced by AA into Mn2+ and catalyze the 3,3',5,5'-tetramethyl benzidine into blue oxidized product for quantification. Using the optimal conditions, the ECAIA could be finished within 132.5 min and shows a limit of detection of 3.38 ng mL-1 (IC10) with an IC50 of 7.65 ng mL-1 and a linear range (IC20-IC80) of 4.55-12.85 ng mL-1. The ECAIA is highly selective for OTA. Good recovery rates (84.3-113%) with a relative standard deviation of 1.3-3% were obtained and confirmed by high performance liquid chromatography with a fluorescence detector. The developed ECAIA was demonstrated to be a useful tool for the detection of OTA in coffee which provides a reference for the analysis of other toxic small molecules.

Development of a horseradish peroxidase-nanobody fusion protein for visual detection of ochratoxin A by dot immunoassay.

Ochratoxin A (OTA) is a common cereal mycotoxin that seriously threatens food safety and public health. Herein a horseradish peroxidase-nanobody fusion protein (HRP-Nb) retaining antibody and enzyme activity was obtained after inclusion body denaturation and renaturation and enzyme reconstitution, which served both as the primary antibody and reporter enzyme and was applied to develop a membrane-based dot immunoassay (HN-DIA) for OTA visual detection. Based on the optimal experimental conditions, the HN-DIA could be finished in 10 min with a cut-off limit of 50 µg kg-1 in rice and oat samples by eye. The HN-DIA showed high selectivity for OTA and had good accuracy and reproducibility in the recovery experiments. Spiked sample analysis results of the HN-DIA and high performance liquid chromatography (HPLC) correlated well with each other. Therefore, the proposed HN-DIA has the potential for rapid screening of OTA and other small molecule pollutants in food and the environment by naked eye.

Preferentially oriented Ag-TiO2 nanotube array film: An efficient visible-light-driven photocatalyst.

Ag-TiO2 nanotube array films with the preferential orientation of crystals were fabricated on ITO glass by magnetron sputtering and anodization. Comprehensive characterization was performed to ascertain the composition and microstructure characteristics of thin films. The photocatalytic activities were evaluated through the reduction of hexavalent chromium (Cr2O72- (Cr (VI)) as a model compound under visible light irradiation. XRD and XPS studies reveal the development of preferred orientation along [001] in anatase TiO2 nanotubes by adjusting the Ag content during magnetron sputtering. Such unusual behavior is attributed to the minimization of anatase (001) surface energy assisted by Ag. The Ag-TiO2 nanotube arrays having preferred crystal orientation exhibit superior separation/transfer of photo-induced charges. Furthermore, the Ag-TiO2 nanotube arrays show improved absorption of visible light due to the SPR effect induced by Ag and the formation of heterojunction between the TNAs and Ag2O. TNA-3Ag exhibits the highest photocatalytic activities by removing 99.1 % Cr (VI) in 90 min under visible light illumination.