Lactic acid fermentation of goji berries (Lycium barbarum) prevents acute alcohol liver injury and modulates gut microbiota and metabolites in mice.

Juice fermented with lactic acid bacteria (LAB) has received attention due to its health benefits, such as antioxidant and anti-inflammatory. Previous research on LAB-fermented goji juice mainly focused on exploring the changes in the metabolite profile and antioxidant activity in vitro, whereas the liver protection properties of LAB-fermented goji juice in vivo are still unknown. This study aimed to investigate the effects of Lacticaseibacillus paracasei E10-fermented goji juice (E10F), Lactiplantibacillus plantarum M-fermented goji juice (MF), Lacticaseibacillus rhamnosus LGG-fermented goji juice (LGGF) on preventing acute alcoholic liver injury with physiology, gut microbial, and metabolic profiles in mice. Compared with goji juice, E10F, MF, and LGGF enhanced the protective effect against liver injury by reducing serum alanine transaminase (ALT) levels, improving the hepatic glutathione (GSH) antioxidant system, and attenuating inflammation by decreasing the levels of interleukin (IL)-1ß, IL-6, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-ß. Furthermore, E10F, MF, and LGGF increased intestinal integrity, restructured the gut microbiota including Bacteroides and Lactobacillus, and altered gut microbial metabolites including kyotorphin, indolelactic acid, and N-methylserotonin. Pretreatment of different LAB-fermented goji juice in mice showed significant differences in gut microbiota and metabolism. The correlation analysis demonstrated that the increase of Lactobacillus, indolelactic acid, and N-methylserotonin by E10F, MF, and LGGF was positively correlated with reduced inflammation and improved liver and gut function. Taken together, E10F, MF, and LGGF all have the potential to be converted into dietary interventions to combat acute alcoholic liver injury. It provided a reference for the study of the hepatoprotective effect of LAB-fermented goji juice.

A natural substitution of a conserved amino acid in eIF4E confers resistance against multiple potyviruses.

Eukaryotic translation initiation factor 4E (eIF4E), which plays a pivotal role in initiating translation in eukaryotic organisms, is often hijacked by the viral genome-linked protein to facilitate the infection of potyviruses. In this study, we found that the naturally occurring amino acid substitution D71G in eIF4E is widely present in potyvirus-resistant watermelon accessions and disrupts the interaction between watermelon eIF4E and viral genome-linked protein of papaya ringspot virus-watermelon strain, zucchini yellow mosaic virus or watermelon mosaic virus. Multiple sequence alignment and protein modelling showed that the amino acid residue D71 located in the cap-binding pocket of eIF4E is strictly conserved in many plant species. The mutation D71G in watermelon eIF4E conferred resistance against papaya ringspot virus-watermelon strain and zucchini yellow mosaic virus, and the equivalent mutation D55G in tobacco eIF4E conferred resistance to potato virus Y. Therefore, our finding provides a potential precise target for breeding plants resistant to multiple potyviruses.

Stabilizing non-iridium active sites by non-stoichiometric oxide for acidic water oxidation at high current density.

Stabilizing active sites of non-iridium-based oxygen evolution reaction (OER) electrocatalysts is crucial, but remains a big challenge for hydrogen production by acidic water splitting. Here, we report that non-stoichiometric Ti oxides (TiOx) can safeguard the Ru sites through structural-confinement and charge-redistribution, thereby extending the catalyst lifetime in acid by 10 orders of magnitude longer compared to that of the stoichiometric one (Ru/TiO2). By exploiting the redox interaction-engaged strategy, the in situ growth of TiOx on Ti foam and the loading of Ru nanoparticles are realized in one step. The as-synthesized binder-free Ru/TiOx catalyst exhibits low OER overpotentials of 174 and 265 mV at 10 and 500 mA cm-2, respectively. Experimental characterizations and theoretical calculations confirm that TiOx stabilizes the Ru active center, enabling operation at 10 mA cm-2 for over 37 days. This work opens an avenue of using non-stoichiometric compounds as stable and active materials for energy technologies.

Mapping port wine stain in vivo by optical coherence tomography angiography and multi-metric characterization.

Port wine stain (PWS) is a congenital cutaneous capillary malformation composed of ecstatic vessels, while the microstructure of these vessels remains largely unknown. Optical coherence tomography angiography (OCTA) serves as a non-invasive, label-free and high-resolution tool to visualize the 3D tissue microvasculature. However, even as the 3D vessel images of PWS become readily accessible, quantitative analysis algorithms for their organization have mainly remained limited to analysis of 2D images. Especially, 3D orientations of vasculature in PWS have not yet been resolved at a voxel-wise basis. In this study, we employed the inverse signal-to-noise ratio (iSNR)-decorrelation (D) OCTA (ID-OCTA) to acquire 3D blood vessel images in vivo from PWS patients, and used the mean-subtraction method for de-shadowing to correct the tail artifacts. We developed algorithms which mapped blood vessels in spatial-angular hyperspace in a 3D context, and obtained orientation-derived metrics including directional variance and waviness for the characterization of vessel alignment and crimping level, respectively. Combining with thickness and local density measures, our method served as a multi-parametric analysis platform which covered a variety of morphological and organizational characteristics at a voxel-wise basis. We found that blood vessels were thicker, denser and less aligned in lesion skin in contrast to normal skin (symmetrical parts of skin lesions on the cheek), and complementary insights from these metrics led to a classification accuracy of ∼90% in identifying PWS. An improvement in sensitivity of 3D analysis was validated over 2D analysis. Our imaging and analysis system provides a clear picture of the microstructure of blood vessels within PWS tissues, which leads to a better understanding of this capillary malformation disease and facilitates improvements in diagnosis and treatment of PWS.

Mapping variation of extracellular matrix in human keloid scar by label-free multiphoton imaging and machine learning.

Significance: Rapid diagnosis and analysis of human keloid scar tissues in an automated manner are essential for understanding pathogenesis and formulating treatment solutions. Aim: Our aim is to resolve the features of the extracellular matrix in human keloid scar tissues automatically for accurate diagnosis with the aid of machine learning. Approach: Multiphoton microscopy was utilized to acquire images of collagen and elastin fibers. Morphological features, histogram, and gray-level co-occurrence matrix-based texture features were obtained to produce a total of 28 features. The minimum redundancy maximum relevancy feature selection approach was implemented to rank these features and establish feature subsets, each of which was employed to build a machine learning model through the tree-based pipeline optimization tool (TPOT). Results: The feature importance ranking was obtained, and 28 feature subsets were acquired by incremental feature selection. The subset with the top 23 features was identified as the most accurate. Then stochastic gradient descent classifier optimized by the TPOT was generated with an accuracy of 96.15% in classifying normal, scar, and adjacent tissues. The area under curve of the classification results (scar versus normal and adjacent, normal versus scar and adjacent, and adjacent versus normal and scar) was 1.0, 1.0, and 0.99, respectively. Conclusions: The proposed approach has great potential for future dermatological clinical diagnosis and analysis and holds promise for the development of computer-aided systems to assist dermatologists in diagnosis and treatment.

Mapping the 3D remodeling of the extracellular matrix in human hypertrophic scar by multi-parametric multiphoton imaging using endogenous contrast.

The hypertrophic scar is an aberrant form of wound healing process, whose clinical efficacy is limited by a lack of understanding of its pathophysiology. Remodeling of collagen and elastin fibers in the extracellular matrix (ECM) is closely associated with scar progression. Herein, we perform label-free multiphoton microscopy (MPM) of both fiber components from human skin specimens and propose a multi-fiber metrics (MFM) analysis model for mapping the structural remodeling of the ECM in hypertrophic scars in a highly-sensitive, three-dimensional (3D) manner. We find that both fiber components become wavier and more disorganized in scar tissues, while content accumulation is observed from elastin fibers only. The 3D MFM analysis can effectively distinguish normal and scar tissues with better than 95% in accuracy and 0.999 in the area under the curve value of the receiver operating characteristic curve. Further, unique organizational features with orderly alignment of both fibers are observed in scar-normal adjacent regions, and an optimized combination of features from 3D MFM analysis enables successful identification of all the boundaries. This imaging and analysis system uncovers the 3D architecture of the ECM in hypertrophic scars and exhibits great translational potential for evaluating scars in vivo and identifying individualized treatment targets.

Low Weight Polysaccharide of Hericium erinaceus Ameliorates Colitis via Inhibiting the NLRP3 Inflammasome Activation in Association with Gut Microbiota Modulation.

Ulcerative colitis (UC), one of the typical inflammatory bowel diseases caused by dysregulated immunity, still requires novel therapeutic medicine with high efficacy and low toxicity. Hericium erinaceus has been widely used to treat different health problems especially gastrointestinal sickness in China for thousands of years. Here, we isolated, purified, and characterized a novel low weight polysaccharide (HEP10, Mw: 9.9 kDa) from the mycelia of H. erinaceus in submerged culture. We explored the therapeutic effect of HEP10 on UC and explored its underlying mechanisms. On one hand, HEP10 suppressed the production of TNF-α, IL-1ß, IL-6, inducible iNOS, and COX-2 in LPS challenged murine macrophage RAW264.7 cells, as well as in colons from DSS-induced colitis mice. On the other hand, HEP10 treatment markedly suppressed the activation of NLRP3 inflammasome, NF-κB, AKT, and MAPK pathways. Moreover, HEP10 reversed DSS-induced alternation of the gut community composition and structure by significantly increasing Akkermansia muciniphila and also promoting functional shifts in gut microbiota. Structural equation modeling also highlighted that HEP10 can change widely through gut microbiota. In conclusion, HEP10 has a better prebiotic effect than the crude polysaccharides of H. erinaceus, which can be used as a novel dietary supplement and prebiotic to ameliorate colitis.

Identification of human ovarian cancer relying on collagen fiber coverage features by quantitative second harmonic generation imaging.

Ovarian cancer has the highest mortality rate among all gynecological cancers, containing complicated heterogeneous histotypes, each with different treatment plans and prognoses. The lack of screening test makes new perspectives for the biomarker of ovarian cancer of great significance. As the main component of extracellular matrix, collagen fibers undergo dynamic remodeling caused by neoplastic activity. Second harmonic generation (SHG) enables label-free, non-destructive imaging of collagen fibers with submicron resolution and deep sectioning. In this study, we developed a new metric named local coverage to quantify morphologically localized distribution of collagen fibers and combined it with overall density to characterize 3D SHG images of collagen fibers from normal, benign and malignant human ovarian biopsies. An overall diagnosis accuracy of 96.3% in distinguishing these tissue types made local and overall density signatures a sensitive biomarker of tumor progression. Quantitative, multi-parametric SHG imaging might serve as a potential screening test tool for ovarian cancer.

Highly accurate, automated quantification of 2D/3D orientation for cerebrovasculature using window optimizing method.

Significance: Deep-imaging of cerebral vessels and accurate organizational characterization are vital to understanding the relationship between tissue structure and function. Aim: We aim at large-depth imaging of the mouse brain vessels based on aggregation-induced emission luminogens (AIEgens), and we create a new algorithm to characterize the spatial orientation adaptively with superior accuracy. Approach: Assisted by AIEgens with near-infrared-II excitation, three-photon fluorescence (3PF) images of large-depth cerebral blood vessels are captured. A window optimizing (WO) method is developed for highly accurate, automated 2D/3D orientation determination. The application of this system is demonstrated by establishing the orientational architecture of mouse cerebrovasculature down to the millimeter-level depth. Results: The WO method is proved to have significantly higher accuracy in both 2D and 3D cases than the method with a fixed window size. Depth- and diameter-dependent orientation information is acquired based on in vivo 3PF imaging and the WO analysis of cerebral vessel images with a penetration depth of 800 µm in mice. Conclusions: We built an imaging and analysis system for cerebrovasculature that is conducive to applications in neuroscience and clinical fields.

Desulfovibrio fairfieldensis-Derived Outer Membrane Vesicles Damage Epithelial Barrier and Induce Inflammation and Pyroptosis in Macrophages.

Sulfate-reducing bacteria Desulfovibrio fairfieldensis is an opportunistic pathogen that widely exists in the human intestine and can cause severe infectious diseases. However, the mechanisms contributing to its pathogenesis remain of great interest. In this study, we aim to investigate the outer membrane vesicles (OMVs) secreted by D. fairfieldensis and their pathogenic effect. The OMVs separated by ultracentrifugation were spherical and displayed a characteristic bilayer lipid structure observed by transmission electron microscopy, with an average hydrodynamic diameter of 75 nm measurement using the particle size analyzer. We identified 1496 and 916 proteins from D. fairfieldensis and its OMVs using label-free non-target quantitative proteomics, respectively. The 560 co-expressed proteins could participate in bacterial life activities by function prediction. The translocation protein TolB, which participates in OMVs biogenesis and transporting toxins was highly expressed in OMVs. The OMVs inhibited the expression of tight junction proteins OCCLUDIN and ZO-1 in human colonic epithelial cells (Caco-2). The OMVs decreased the cell viability of monocyte macrophages (THP-1-Mφ) and activated various inflammatory factors secretion, including interferon-γ (IFN-γ), tumor necrosis factor (TNF-α), and many interleukins. Further, we found the OMVs induced the expression of cleaved-gasdermin D, caspase-1, and c-IL-1ß and caused pyroptosis in THP-1-Mφ cells. Taken together, these data reveal that the D. fairfieldensis OMVs can damage the intestinal epithelial barrier and activate intrinsic inflammation.

A tobacco ringspot virus-based vector system for gene and microRNA function studies in cucurbits.

Cucurbits are economically important crops worldwide. The genomic data of many cucurbits are now available. However, functional analyses of cucurbit genes and noncoding RNAs have been impeded because genetic transformation is difficult for many cucurbitaceous plants. Here, we developed a set of tobacco ringspot virus (TRSV)-based vectors for gene and microRNA (miRNA) function studies in cucurbits. A TRSV-based expression vector could simultaneously express GREEN FLUORESCENT PROTEIN (GFP) and heterologous viral suppressors of RNA silencing in TRSV-infected plants, while a TRSV-based gene silencing vector could knock down endogenous genes exemplified by PHYTOENE DESATURASE (PDS) in Cucumis melo, Citrullus lanatus, Cucumis sativus, and Nicotiana benthamiana plants. We also developed a TRSV-based miRNA silencing vector to dissect the functions of endogenous miRNAs. Four representative miRNAs, namely, miR159, miR166, miR172, and miR319, from different cucurbits were inserted into the TRSV vector using a short tandem target mimic strategy and induced characteristic phenotypes in TRSV-miRNA-infected plants. This TRSV-based vector system will facilitate functional genomic studies in cucurbits.

Oxygenated functional group-driven spontaneous fabrication of Pd nanoparticles decorated porous carbon nanosheets for electrocatalytic hydrodechlorination of 4-chlorophenol.

Researchers have been committed to reducing the hazardous pollutants by developing efficient catalysts while ignoring the pollution caused by the use of toxic surface capping agents, reductants and/or organic solvents in the catalyst preparation process. To alleviate such problems, we here report a novel one-step oxygenated functional group-driven electroless deposition strategy to synthesize clean and uniformly distributed Pd nanoparticles (NPs) using porous carbon nanosheets (PCN) as both substrates and reducing agents. It is observed that the oxygenated functional groups enriched PCN possesses a low work function and allows the spontaneous reduction of PdCl42- ions to Pd NPs deposited on the PCN support (Pd/PCN). The particle size of Pd NPs can be flexibly modulated by simply controlling the immersing time and thereby their maximum catalytic performances can be achieved. Specifically, the optimal Pd/PCN-08 with a Pd loading of 3.0 wt% shows an excellent activity with a turnover frequency of 0.38 min-1 for electrocatalytic hydrodechlorination (ECH) of 4-chlorophenol (4-CP), superior to the previously reported materials. The stability of Pd/PCN-08 for 4-CP ECH is impressive in repetitive cycles. This work proposes a facile and efficient strategy to synthesize high-performance catalysts for detoxifying the hazardous organic pollutants.

Oxygenated functional group-engaged electroless deposition of ligand-free silver nanoparticles on porous carbon for efficient electrochemical non-enzymatic H2O2 detection.

The construction of metal-carbon nanostructures with enhanced performances using traditional methods, such as pyrolysis, photolysis, impregnation-reduction, etc., generally requires additional energy input, reducing agents and capping ligands, which inevitably increase the manufacturing cost and environmental pollution. Herein, a novel one-step substrate-induced electroless deposition (SIED) strategy is developed to synthesize ligand-free Ag NPs supported on porous carbon (PC) (Ag/PC). The PC matrix enriched with oxygenated functional groups has a low work function and thus a low redox potential compared to that of Ag+ ions, which induces the auto-reduction of Ag+ ions to Ag NPs. The as-synthesized Ag/PC-6 modified electrode can be used as an excellent nonenzymatic H2O2 sensor with a broad linear range of 0.001-20 mM, a low detection limit of 0.729 µM (S/N = 3), and a high response sensitivity of 226.9 µA mM-1 cm-2, outperforming most of the reported sensor materials. Moreover, this electrode can be applied to detect trace amounts of H2O2 in juice and milk samples below the permitted residual level in food packaging and the recovery of H2O2 is 99.6% in blood serum (10%) with good reproducibility. This study proposes an efficient approach for synthesizing a highly active supported Ag electrocatalyst, which shows significant potential for practical applications.

Protective Effect of Spore Powder of Antrodia camphorata ATCC 200183 on CCl4-Induced Liver Fibrosis in Mice.

Liver fibrosis is a pathological process with intrahepatic diffused deposition of the excess extracellular matrix, which leads to various chronic liver diseases. Drugs with high efficacy and low toxicity for liver fibrosis are still unavailable. Antrodia camphorata has antioxidant, antivirus, antitumor and anti-inflammation roles, and has been used to treat liver diseases in the population. However, the hepatoprotective effects of A. camphorata spores and the mechanisms behind it have not been investigated. In this study, we evaluate the hepatoprotective effect of spore powder of A. camphorata (SP, 100 mg/kg/day or 200 mg/kg/day) on carbon tetrachloride (CCl4)-induced liver fibrosis in mice. SP groups reduced serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities compared with the CCl4 group. SP also showed a decrease in hydroxyproline (Hyp) content in liver tissues. SP improved cell damage and reduced collagen deposition by H&E, Sirius red and Masson staining. Furthermore, SP down-regulated the mRNA levels of α-SMA and Col 1, and the protein expression of α-smooth muscle actin (α-SMA), collagen I (Col 1), tumor necrosis factor alpha (TNF-α), toll like receptor 4 (TLR4) and nuclear factor-Κb (NF-κB) p65. In summary, SP has an ameliorative effect on hepatic fibrosis, probably by inhibiting the activation of hepatic stellate cells, reducing the synthesis of extracellular matrix.

Flexible Active-Site Engineering of Monometallic Co-Layered Double Hydroxides for Achieving High-Performance Bifunctional Electrocatalyst toward Oxygen Evolution and H2O2 Reduction.

It is highly desirable but challenging to develop a facile and scalable strategy to synthesize efficient bifunctional electrocatalysts for oxygen evolution and H2O2 reduction by engineering the active site of monometallic-layered double hydroxides (LDHs). Herein, we developed a convenient, efficient, and scalable method for the construction of monometallic Co-LDHs with tunable Con+ (n = 2, 3) concentration by a one-pot solvothermal reaction in a short time (e.g., 2 and 4 h) using only cobalt nitrate and hexamine as raw materials. The catalytic performance of Co-LDHs was mainly determined by the Con+ (n = 2, 3) concentration, which could be simply regulated by tuning the solvothermal time. Combining the joint merits of three-dimensional flowerlike architecture (abundant accessible active sites and a fast electron/mass transport), Co-LDHs-4 with abundant Co3+ species exhibited an excellent electrocatalytic activity for oxygen evolution reaction in terms of a low overpotential at 10 mA cm-2 (η10 = 241 mV) and long-term durability for 70 h at 100 mA cm-2, better than the state-of-the-art IrO2 and most of the reported analogues. Besides, Co-LDHs-2 enriched in Co2+ displayed a superior electrochemical activity for H2O2 detection with a broad linear range (0.002-20 mM), a low detection limit (0.002 mM), and a high response sensitivity (272.02 µA mM-1 cm-2). Therefore, this work opens a new horizon for the rational development of a highly active electrocatalyst with tunable concentrations of active components.

Modulation of defects and electrical behaviors of Cu-doped KNN ceramics by fluorine-oxygen substitution.

The lead-free piezoceramics of K0.5Na0.5Nb0.996Cu0.01O3-xFx (KNCNF-x) were synthesized via a conventional solid sintering process, and the inhibition effects of F-O substitution on the defect structures of oxygen vacancies and defect complexes were investigated. The KNCNF-0 ceramic without F doping has the highest level of oxygen vacancies and defect complexes. However, as the level of F increases, the contents of oxygen vacancies and defect complexes decrease correspondingly, and thus, the evolution of hardening to softening behaviors in the ceramics is observed. As a result, the KNCNF-0 piezoceramic shows extremely hardened electrical behaviors (a completely constricted P-E hysteresis loop, large Ei of 10.7 kV cm-1, kp of 38%, d33 of 83 pC N-1, Qm of 3110, and tan δ of 0.2%), while the ceramic with x = 0.28 exhibits softened ferroelectric and piezoelectric characteristics (a non-shrinking P-E hysteresis loop, declining Ei of 7.5 kV cm-1, enhanced kp of 42%, optimized d33 of 103 pC N-1, reduced Qm of 1031, and increased tan δ of 0.6%). This study provides new insights into the modulation of defects and electrical performance of KNN ceramics.

One-step synthesis of wire-in-plate nanostructured materials made of CoFe-LDH nanoplates coupled with Co(OH)2 nanowires grown on a Ni foam for a high-efficiency oxygen evolution reaction.

Developing high-performance, robust and cost-effective oxygen evolution reaction (OER) catalysts for electrochemical water splitting is a promising way to produce energy-saving electrolytic hydrogen fuels. Herein, a series of rational wire-in-plate nanostructured CoFe LDH electrocatalysts grown on a Ni foam were developed via a one-step hydrothermal method. In this series of catalysts, Co4Fe2-LDHs/Co(OH)2-NWs exhibit excellent OER performance which is attributed to the most rational wire-in-plate nanostructure: the overpotentials of only 220 and 231 mV to drive current densities of 50 mA cm-2 and 100 mA cm-2, respectively, with a small Tafel slope of 51 mV dec-1. Our study opens up a new horizon for the design of hierarchical structures with the coexistence of multidimensional nanounits for electrocatalysts.

Ratios of greenhouse gas emissions observed over the Yellow Sea and the East China Sea.

During a cruise of the survey vessel Dongfanghong II on the Yellow Sea and the East China Sea in the spring of 2017 we performed accurate measurements of the mole fractions of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO) and nitrous oxide (N2O) using two types of Cavity Ring-Down Spectrometers (CRDS). The spatial variations of the mole fraction of the four trace gases were very similar. The emission sources of these gases were divided into several regions by using the NOAA HYSPLIT model. Then we analyzed the variations of the ratios of the mole fraction enhancements between every pair of trace gases downwind of these source areas. The ratios showed that the distributions of these trace gases over the Yellow Sea and the East China Sea in the spring were mainly caused by the emissions from Eastern China. The much higher enhancement ratio of ΔCO/ΔCO2 and the lower ratio of ΔCH4/ΔCO observed in the air parcels from big cities like Beijing and Shanghai indicated high CO emission from the cities during our time of observation. Compared with the values of NOAA's Marine Boundary Layer (MBL), the ratios of the averages in the air coming from the Northern sector (Russia) were on average closer to the MBL, and the air that stayed over the Yellow Sea and the East China Sea was a mixture of emissions from wide regional areas. The highly variable N2O data of the air from Qingdao and Shanghai showed much more fluctuation.

Formation of inorganic nitrogenous byproducts in aqueous solution under ultrasound irradiation.

The effects of ultrasonic frequency, power intensity, temperature and sparged gas on the generation of nitrogenous by-products NO2- and NO3- have been investigated, and the new kinetics model of NO2- and NO3- generation was also explored. The results show that the highest primary generation rate of NO2- and NO3- by direct sonolysis in the cavitation bubbles (represented by k1' and k2', respectively) was obtained at 600 kHz and 200 kHz, respectively, in the applied ultrasonic frequency range of 200 to 800 kHz. The primary generation rate of NO2- (represented by k1') increased with the increasing ultrasonic intensity while the primary generation rate of NO3- (represented by k2') decreased. The lower temperature is beneficial to the primary generation of both NO2- and NO3- in the cavitation bubbles. The optimal overall yields of both NO2- and NO3- were obtained at the N2/O2 volume (in the sparged gas) ratio of 3:1 which is near to the ratio of N2/O2 in air. The dissolved O2 is the dominant oxygen element source for both NO and NO2, compared with water vapor. Ultrasonic irradiation can significant enhance the recovery rates of dissolved N2 and O2 and thus keep the N2 fixation reaction going even without aeration.