Digital Circulating Tumor Cells Quantification.

Circulating tumor cells (CTCs) are an emerging but vital biomarker for cancer management. An efficient methodology for accurately quantifying CTCs remains challenging due to their rareness. Here, we develop a digital CTC detection strategy using partitioning instead of enrichment to quantify CTCs. By utilizing the characteristics of droplet microfluidics that can rapidly generate a large number of parallel independent reactors, combined with Poisson distribution, we realize the quantification of CTCs in the blood directly. The limit of detection of our digital CTCs quantification assay is five cells per 5 mL of whole blood. By simultaneously detecting multiple genetic mutations, our approach achieves highly sensitive and specific detection of CTCs in peripheral blood from NSCLC patients (AUC = 1). Our digital platform offers a potential approach and strategy for the quantification of CTCs, which could contribute to the advancement of cancer medical management.

Electrochemical Monitoring of Sphingosine-1-phosphate-Induced ATP Release Using a Microsensor Based on an Entropy-Driven Bipedal DNA Walker.

Neuropathic pain is a chronic and severe syndrome for which effective therapy is insufficient and the release of ATP from microglia induced by sphingosine-1-phosphate (S1P) plays a vital role in neuropathic pain. Therefore, there is an urgent demand to develop highly sensitive and selective ATP biosensors for quantitative monitoring of low-concentration ATP in the complex nervous system, which helps in understanding the mechanism involved in neuropathic pain. Herein, we developed an electrochemical microsensor based on an entropy-driven bipedal DNA walker. First, the microsensor specifically recognized ATP via ATP aptamers, initiating the entropy-driven bipedal DNA walker. Subsequently, the bipedal DNA walker autonomously traversed the microelectrode interface, introducing methylene blue to the electrode surface and achieving cascade signal amplification. This microsensor showed excellent selectivity, stability, and a low limit of detection at 1.13 nM. The S1P-induced ATP release from BV2 cells was successfully monitored, and it was observed that dicumarol could inhibit this release, suggesting dicumarol as a potential treatment for neuropathic pain. The microsensor's small size exhibited significant potential for monitoring ATP level changes in neuropathic pain in vivo, which provides a new strategy for in situ and quantitative monitoring of nonelectroactive biomolecules associated with neurological diseases.

Mechanisms of biodiversity loss under nitrogen enrichment: unveiling a shift from light competition to cation toxicity.

The primary mechanisms contributing to nitrogen (N) addition induced grassland biodiversity loss, namely light competition and soil cation toxicity, are often examined separately in various studies. However, their relative significance in governing biodiversity loss along N addition gradient remains unclear. We conducted a 4-yr field experiment with five N addition rates (0, 2, 10, 20, and 50 g N m-2 yr-1) and performed a meta-analysis using global data from 239 observations in N-fertilized grassland ecosystems. Results from our field experiment and meta-analysis indicate that both light competition and soil cation (e.g. Mn2+ and Al3+) toxicity contribute to plant diversity loss under N enrichment. The relative importance of these mechanisms varied with N enrichment intensity. Light competition played a more significant role in influencing species richness under low N addition (≤ 10 g m-2 yr-1), while cation toxicity became increasingly dominant in reducing biodiversity under high N addition (>10 g m-2 yr-1). Therefore, a transition from light competition to cation toxicity occurs with increasing N availability. These findings imply that the biodiversity loss along the N gradient is regulated by distinct mechanisms, necessitating the adoption of differential management strategies to mitigate diversity loss under varying intensities of N enrichment.

Long-Term Organic Fertilization Strengthens the Soil Phosphorus Cycle and Phosphorus Availability by Regulating the pqqC- and phoD-Harboring Bacterial Communities.

The pqqC and phoD genes encode pyrroloquinoline quinone synthase and alkaline phosphomonoesterase (ALP), respectively. These genes play a crucial role in regulating the solubilization of inorganic phosphorus (Pi) and the mineralization of organic phosphorus (Po), making them valuable markers for P-mobilizing bacterial. However, there is limited understanding of how the interplay between soil P-mobilizing bacterial communities and abiotic factors influences P transformation and availability in the context of long-term fertilization scenarios. We used real-time polymerase chain reaction and high-throughput sequencing to explore the characteristics of soil P-mobilizing bacterial communities and their relationships with key physicochemical properties and P fractions under long-term fertilization scenarios. In a 38-year fertilization experiment, six fertilization treatments were selected. These treatments were sorted into three groups: the non-P-amended group, including no fertilization and mineral NK fertilizer; the sole mineral-P-amended group, including mineral NP and NPK fertilizer; and the organically amended group, including sole organic fertilizer and organic fertilizer plus mineral NPK fertilizer. The organically amended group significantly increased soil labile P (Ca2-P and enzyme-P) and Olsen-P content and proportion but decreased non-labile P (Ca10-P) proportion compared with the sole mineral-P-amended group, indicating enhanced P availability in the soil. Meanwhile, the organically amended group significantly increased soil ALP activity and pqqC and phoD gene abundances, indicating that organic fertilization promotes the activity and abundance of microorganisms involved in P mobilization processes. Interestingly, the organically amended group dramatically reshaped the community structure of P-mobilizing bacteria and increased the relative abundance of Acidiphilium, Panacagrimonas, Hansschlegelia, and Beijerinckia. These changes had a greater positive impact on ALP activity, labile P, and Olsen-P content compared to the abundance of P-mobilizing genes alone, indicating their importance in driving P mobilization processes. Structural equation modeling indicated that soil organic carbon and Po modulated the relationship between P-mobilizing bacterial communities and labile P and Olsen-P, highlighting the influence of SOC and Po on the functioning of P-mobilizing bacteria and their impact on P availability. Overall, our study demonstrates that organic fertilization has the potential to reshape the structure of P-mobilizing bacterial communities, leading to increased P mobilization and availability in the soil. These findings contribute to our understanding of the mechanisms underlying P cycling in agricultural systems and provide valuable insights for enhancing microbial P mobilization through organic fertilization.

Anulamycins A-F, Cinnamoyl-Containing Peptides from a Lake Sediment Derived Streptomyces.

Bioinformatics analysis of a whole genome sequence coupled with HPLC-DAD analysis revealed that Streptomyces sp. Hu103 has the capacity to produce skyllamycin analogues. A subsequent chemical investigation of this strain yielded four new cinnamoyl-containing cyclopeptides, anulamycins A-D (1-4), two new cinnamoyl-containing linear peptides, anulamycins E and F (5 and 6), and two known cyclopeptides, skyllamycins A (7) and B (8). Their structures including absolute configurations were elucidated by detailed analysis of NMR and HRESIMS/MS spectroscopic data and the advanced Marfey's method. Compounds 1-4 exhibited antibacterial activity comparable to those of skyllamycins A and B.

CdSe@CdS quantum dot-sensitized Au/α-Fe2O3 structure for photoelectrochemical detection of circulating tumor cells.

Circulating tumor cells (CTCs) are the important biomarker for cancer diagnosis and individualized treatment. However, due to the extreme rarity of CTCs (only 1-10 CTCs are found in every milliliter of peripheral blood) high sensitivity and selectivity are urgently needed for CTC detection. Here, a sandwich PEC cytosensor for the ultrasensitive detection of CTCs was developed using the photoactive material Au NP/-Fe2O3 and core-shell CdSe@CdS QD sensitizer. In the proposed  protocol, the CdSe@CdS QD/Au NP/α-Fe2O3-sensitized structure with cascade band-edge levels could evidently promote the photoelectric conversion efficiency due to suitable light absorption and efficient electron-hole pair recombination inhibition. Additionally, a dendritic aptamer-DNA concatemer was constructed for highly efficient capture of MCF-7 cells carrying CdSe@CdS QDs, a sensitive material. The linear range of this proposed signal-on PEC sensing method was 300 cell mL-1 to 6 × 105 cell mL-1 with a detection limit of 3 cell mL-1, and it demonstrated an ultrasensitive response to CTCs. Furthermore, this PEC sensor enabled accurate detection of  CTCs in serum samples. Hence, a promising strategy for CTC detection in clinical diagnosis was developed based on CdSe@CdS QD-sensitized Au NP/α-Fe2O3-based PEC cytosensor with dendritic aptamer-DNA concatemer.

Gallic acid improves the metformin effects on diabetic kidney disease in mice.

OBJECTIVES: Metformin is an antidiabetic agent that is used as the first-line treatment of type 2 diabetes mellitus. Gallic acid is a type of phenolic acid that has been shown to be a potential drug candidate to treat diabetic kidney disease, an important complication of diabetes. We aimed to test whether a combination of gallic acid and metformin can exert synergetic effect on diabetic kidney disease in diabetic mice model. METHODS: Streptozotocin (65 mg/kg) intraperitoneal injection was used to induce diabetic kidney disease in mice. The diabetic mice were treated with saline (Vehicle), gallic acid (GA) (30 mg/kg), metformin (MET) (200 mg/kg), or the combination of gallic acid (30 mg/kg) and metformin (200 mg/kg) (GA + MET). RESULTS: Our results demonstrated that compared to the untreated diabetic mice, all three strategies (GA, MET, and GA + MET) exhibited various effects on improving renal morphology and functions, reducing oxidative stress in kidney tissues, and restoring AMP-activated protein kinase (AMPK)/silent mating type information regulation 2 homolog 1 (SIRT1) signaling in kidney tissues of diabetic mice. Notably, the combination strategy (GA + MET) provided the most potent renal protection effects than any single strategies (GA or MET). CONCLUSION: Our results support the hypothesis that gallic acid might serve as a potential supplement to metformin to enhance the therapeutical effect of metformin.

Phenopyrrolizins A and B, Two Novel Pyrrolizine Alkaloids from Marine-Derived Actinomycetes Micromonospora sp. HU138.

Two previously undescribed pyrrolizine alkaloids, named phenopyrrolizins A and B (1 and 2), were obtained from the fermentation broth of marine-derived Micromonospora sp. HU138. Their structures were established by extensive spectroscopic analysis, including 1D and 2D NMR spectra as well as HRESIMS data. The structure of 1 was confirmed by single-crystal diffraction analysis and its racemization mechanism was proposed. The antifungal activity assay showed that 2 could inhibit the mycelial growth of Botrytis cinerea with the inhibitory rates of 18.9% and 35.9% at 20 µg/disc and 40 µg/disc, respectively.

Rapid Antimicrobial Susceptibility Testing Based on a Bio-Inspired Chemiluminescence Sensor.

Indiscriminate usage of antibiotics has caused accelerating growth and global expansion of antimicrobial resistance. Therefore, rapid antimicrobial susceptibility testing (AST) for guiding antibiotic prescription and preventing the spread of antimicrobial resistance is in urgent need. Phenotypic AST is the clinical gold standard method; however, no phenotypic AST has realized a colony-to-answer at about 1 h by utilizing the chemiluminescence sensor to detect the enzyme expressed by bacteria. Inspired by the bubble formation in the mixture of Escherichia coli and H2O2, we demonstrate a strategy based on the chemiluminescence sensor for rapid AST. Compared with the gold standard methods, the values of AUC are 0.960 for E. coli and 0.950 for Staphylococcus aureus, close to 1, indicating superb diagnostic performance as an AST method. The whole process from colonies to answer is 55 min for E. coli and 70 min for S. aureus. The chemiluminescence readout is based on the common equipment in the laboratory of the hospital, which is conducive to follow-up clinical promotion. Our sensor promises great potential in rapid AST, facilitating antimicrobial stewardship.

Rapid In Situ Hydrogel LAMP for On-Site Large-Scale Parallel Single-Cell HPV Detection.

Rapid human papillomavirus (HPV) screening is urgently needed for preventing and early diagnosis of cervical cancer in rural areas. To date, no HPV nucleic acid test (NAT) can be implemented within a single patient visit starting from clinical samples. Here, we develop a hydrogel loop-mediated isothermal amplification (LAMP) method in a fashion of large-scale parallel (about 1000 cells) in situ HPV DNA detection in clinical cervical exfoliated cells at the single-cell level. It can be used with a hotplate and smartphone to obtain HPV NAT results in less than 30 min, which is especially suitable for the on-site scenario. We apply this rapid HPV NAT on 40 clinical cervical exfoliated cell samples and compare the results to a clinical gold standard quantitative polymerase chain reaction (qPCR) method [area under curve (AUC), 1.00]. Meanwhile, our assay can provide HPV infection information for large-scale parallel single clinical cervical exfoliated cells, which cannot be received from traditional NAT methods. Our findings suggest the potential of in situ hydrogel LAMP as a powerful tool for clinical HPV screening and fundamental research.

Room-Temperature Harvesting Oxidase-Mimicking Enzymes with Exogenous ROS Generation in One Step.

Despite the advantages of low cost, high stability, and activities, a majority of nanozymes rely on strict synthesis conditions and precise size/structure control, hindering the stable, bulk, and high-yield production that is necessary for general use. To facilitate the transition of nanozymes from benchtop to real-world applications, we herein present a one-step approach, which only needs mixing of two broad commercialized reagents at room temperature, to harvest gold nanoparticles-bovine serum albumin (BSA) nanocomposite (BSA-Au) with distinct oxidase-like activity and good stability in a broad range of harsh conditions. Density functional theory (DFT) calculations demonstrate the oxidase-like activity of BSA-Au stemming from thermodynamically and kinetically favored facets for O2 activation. The reactive oxygen species (ROS) generation of BSA-Au contributes to the catalytic activities and further enables water sterilization and antibacterial applications against superbugs. This one-step strategy promises great potential in bulk production of nanozyme for broad application beyond laboratory use.

Safety and efficacy analysis of chemoradiotherapy/radiotherapy combined with nimotuzumab for treating unresectable oesophageal squamous cell carcinoma in elderly patients: a retrospective analysis.

OBJECTIVE: To investigate the safety and efficacy of chemoradiotherapy or radiotherapy combined with nimotuzumab in the treatment of unresectable oesophageal squamous cell carcinoma (ESCC) in elderly patients. METHODS: This study retrospectively analysed 54 cases of elderly patients (aged over 70 years) with unresectable ESCC in our centre between December 2016 and November 2019. The patients were treated with a radiation dose of 50-61.6 Gy (25-30 fractions) combined with nimotuzumab for targeted therapy with or without chemotherapy according to each patient's condition. The patients were observed for quality of life, safety, side effects and survival before and after the treatment. RESULTS: Among the 54 patients, 26 were treated with nimotuzumab combined with chemoradiotherapy and 28 were treated with nimotuzumab combined with radiotherapy. Toxicities were mainly oesophagitis (≥ Grade 2, 38.9%), myelosuppression (≥ Grade 3, 24.1%) and hypoproteinaemia (any grade, 94.4%). The rates of complete response, partial response, disease stability and disease progression were 11.1% (6/54), 81.5% (44/54), 3.7% (2/54) and 3.7% (2/54), respectively, and the overall objective response rate was 92.6% (50/54). The median follow-up time was 35.1 months, and the 1- and 2-year overall survival (OS) and progression-free survival (PFS) rates were 61.1% (1 year OS) and 35.2% (2 year OS), 42.6% (1 year PFS) and 16.7% (2 year PFS), respectively. The median OS and PFS rates were 16.0 and 10.0 months, respectively. CONCLUSION: Nimotuzumab combined with chemoradiotherapy or radiotherapy was well tolerated in elderly patients with unresectable ESCC. This combination can achieve a good treatment response and enhance survival.

Hydroxy-selenomethionine supplementation promotes the in vitro rumen fermentation of dairy cows by altering the relative abundance of rumen microorganisms.

AIMS: This study aims to investigate the effect of hydroxy-selenomethionine supplementation on the in vitro rumen fermentation characteristics and microorganisms of Holstein cows. METHODS AND RESULTS: Five fermentation substrates, including control (without selenium supplementation, CON), sodium selenite supplementation (0.3 mg kg-1 DM, SS03), and hydroxy-selenomethionine supplementation (0.3, 0.6 and 0.9 mg kg-1 DM, SM03, SM06 and SM09, respectively) were incubated with rumen fluid in vitro. The results showed that in vitro dry matter disappearance and gas production at 48 h was significantly higher in SM06 than SM03, SS03 and CON; propionate and total volatile fatty acid (VFA) production was higher in SM06 than CON. Moreover, higher species richness of rumen fluid was found in SM06 than others. Higher relative abundance of Prevotella and Prevotellaceae-UCG-003 and lower relative abundance of Ruminococcus-1 were detected in SM06 than CON. Besides, higher relative abundance of Ruminococcaceae_UCG-005 was found in CON than other treatments. CONCLUSIONS: It is observed that 0.6 mg kg-1 DM hydroxy-selenomethionine supplementation could increase cumulative gas production, propionate, and total VFAs production by altering the relative abundance of Prevotella, Prevotellaceae-UCG-003, Ruminococcaceae_UCG-005 and Ruminococcus-1, so that it can be used as a rumen fermentation regulator in Holstein cows. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides an optimal addition ratio of hydroxy-selenomethionine on rumen fermentation and bacterial composition via an in vitro test.

Sarubicinols A-C, Cytotoxic Benzoxazoles from a Streptomyces.

A chemical investigation of Streptomyces sp. Hu186 afforded two known quinone antibiotics, sarubicin A (1) and sarubicin B (2), together with three unusual variants, sarubicinols A-C (3-5), and two new 1,4-naphthoquinone metabolites, sarubicin B1 (6) and sarubicin B2 (7). Compounds 3-5 possess a rare 2-oxabicyclo [2.2.2] substructure and a benzoxazole ring system. Their structures were elucidated using 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry data. The absolute configurations of the side-chain moieties in 4 and 5 were solved by electronic circular dichroism calculations. Compounds 1-7 showed moderate cytotoxic activity against four tumor cell lines.

Tetrodecadazinone, a novel tetrodecamycin-pyridazinone hybrid with anti-liver fibrosis activity from Streptomyces sp. HU051.

Tetrodecadazinone (1), a novel tetrodecamycin-pyridazinone hybrid possessing a new 1,2-dimethyl-1-(2-methylnonyl)decahydronaphthalene skeleton, and 4-hydroxydihydrotetrodecamycin (2) were separated from a culture of Streptomyces sp. HU051, together with a known compound, dihydrotetrodecamycin (3). Diverse spectroscopic approaches were applied to assign the structures of 1-3, and the structure of 1 was further confirmed by single crystal X-ray diffraction analysis. Compound 1 is the first example of a pyridazinone-containing natural product. Biosynthetically, 1 is proposed to be derived from a Michael addition reaction of a PKS-derived tetrodecamycin and a piperazic-acid-derived pyridazinone. Biological evaluation revealed 1 could reduce the expressions of extracellular matrix proteins (fibronectin and collagen I) and α-smooth muscle actin (α-SMA) in transforming growth factor-ß (TGF-ß1)-activated LX-2 cells. Preliminary mechanism study showed 1 exerted its anti-liver fibrosis effect by regulating TGF-ß1/Smad2/3 signaling pathway.

First Report of Trichothecium roseum Causing Postharvest Fruit Rot on Purple Passion Fruit in China.

Purple Passion fruit (Passiflora edulis) is widely cultivated in many regions of southern China as an edible tropical fruit with excellent nutritional value and high economic value. In July 2021, postharvest fruit rot was observed on 20-25% of purple passion fruit in several fruit markets of Dehong City in Yunnan Province. Symptoms on infected fruits were irregular, pink-brown, soft, and water-soaked lesions, which enlarged and formed sunken patches with time as well as producing a small amount of white mycelium. To isolate the causal organism, five diseased fruits were collected from different fruit markets. A conidial mass from an individual sorus observed on an infected fruit was isolated and cultured on potato dextrose agar (PDA) supplemented with 50 µg ml-1 of streptomycin, and five fungal isolates were obtained. These isolates were morphologically similar and produced pale pink colonies on PDA for 7 days containing several conidiophores with abundant conidia. Mycelia were hyaline, 2 µm in diameter, and conidiophores were simple or branched (100 to 286 × 1.5 to 2.5 µm, n=50). Conidia were pyriform, ovate, with papillary protuberances at one end. Almost all conidia were two-celled and single-septate (5.8 to 9.1 × 1.7 to 4.9 µm, n=50). The morphology of the fungi resembled Trichothecium roseum as reported previously (Inácio et al. 2011). To further confirm the fungal species, isolate PASF4 was selected for molecular identification by amplifying and sequencing the ribosomal internal transcribed spacer (ITS) and large subunit (LSU) genes. Primers and PCR amplification were described by Fell et al. (2000). Results showed that both the ITS (GenBank accession OL336243) and LSU (OL336242) gene sequences had 100% similarity to T. roseum in NCBI database (MH856757 and MH868278). Maximum likelihood tree was constructed using MEGA 7 (Felsenstein, 1981) based on concatenated sequences (ITS and LSU) of isolate PASF4 and reference strains. Phylogenetic analysis showed that isolate PASF4 belonged to T. roseum clade. Based on morphological characteristics and phylogenetic analysis, isolate PASF4 was identified as T. roseum (Inácio et al. 2011). To confirm their pathogenicity, healthy purple passion fruits (cv. Tainong-1) were disinfected in 0.5% NaClO solution for 2 min, and then washed with sterile water. After wounding with a sterile needle, the fruits were inoculated by placing mycelium agar plugs on the wounds, and mock inoculation with mycelium-free PDA plugs served as control. Five fruits were used in each treatment. All fruits were maintained in plastic boxes at 25 °C. Disease symptoms appeared after inoculation for 4-7 days on all inoculated fruits, which were similar to those observed in fruit markets. No symptoms were observed on fruits used as control. The Trichothecium isolates were re-isolated from symptomatic fruits thus fulfilling Koch's postulates. Trichothecium roseum has been reported to cause fruit rot of tomato, apple and orange in Pakistan (Hamid et al., 2014) and fruit rot of pepper in China (Lin et al., 2016). To our knowledge, this is the first report of T. roseum causing fruit rot on purple passion fruit worldwide, and these data will provide useful information for developing effective control strategies.

Two new cyclopentenone metabolites from Streptomyces sp. HU119.

Two previously undescribed cyclopentenone metabolites, (S)-2-(3-acetylamino-2-methyl)propyl-3-butyl-2-cyclopenten-1-one (1) and (S)-2-(3-acetylamino-2-ethyl)propyl-3-butyl-2-cyclopenten-1-one (2), were isolated from the fermentation broth of the strain Streptomyces sp. HU119. The structures of 1 and 2 were determined by the comprehensive spectroscopic analysis, including 1 D, 2 D NMR, MS spectral analysis and the comparison with data from the literature. The absolute configurations were elucidated by experimental and calculated optical rotations (OR). Compounds 1 and 2 displayed weak cytotoxic activity.

Optimizing organic amendment applications to enhance carbon sequestration and economic benefits in an infertile sandy soil.

A thorough understanding of the agricultural, ecological, and economic benefits of organic amendment (OA) application in infertile soils is crucial for facilitating agricultural sustainability. We conducted a three-year field study to evaluate the effects of OA application on soil organic carbon (SOC) sequestration, crop yields, and the net ecosystem economic benefit (NEEB) in a typical infertile sandy soil (with an initial SOC content of 2.56 g kg-1) of the ancient Yellow River alluvial plain. In addition to the control (CK; non-OA application), two types of OAs, namely, manure-based organic fertilizer (M) and spent mushroom residue (MR), were each applied at 12, 24, and 36 Mg ha-1 yr-1. Two scenarios of OA application practices, namely, conventional manual OA application (AMA) and mechanical OA application (AME), were considered in the economic evaluation. An increase of 1 g kg-1 SOC content could improve the crop yield by 2.25 Mg ha-1 yr-1. Compared with the CK, the application of OAs enhanced the SOC content and SOC stock by 14.6%-39.8% and 8.5%-28.2%, respectively. However, the SOC sequestration efficiency of the OAs tended to decrease under high rates of OA application. MR was observed to have greater potential than M in sequestering SOC and promoting soil aggregates. OA-induced SOC sequestration could neutralize 36.6%-97.8% of greenhouse gas emissions, which resulted in a reduction in the global warming potential and its cost by 0.62-2.68 Mg CO2-eq ha-1 yr-1 and 15.46-65.78 CNY ha-1 yr-1, respectively. Nevertheless, in terms of the NEEB, the benefits of OA application on crop yield and SOC sequestration were largely offset by the increased material and labor costs. Compared with AMA, AME could save 10%-27% of agricultural costs. The AME of MR at a rate of 24 Mg ha-1 yr-1 achieved the highest NEEB. The results of this study suggest that a strategy involving the appropriate OA, optimal application rate, and cheapest incorporation cost for a specific individual soil should be adopted to achieve a sustainable solution for promoting crop productivity, enhancing SOC sequestration, and ensuring farmer income in infertile farming regions.

Reduced nitrogen fertilization under flooded conditions cut down soil N2O and CO2 efflux: An incubation experiment.

Unreasonable water (W) and inorganic nitrogen (N) fertilization cause an intensification of soil greenhouse gas (GHGs) emissions. W-N interactions (W × N) patterns can maximise the regulation of soil GHGs efflux through the rational matching of W and N fertilization factors. However, the effects of W × N patterns on soil GHGs efflux and the underlying mechanism remain unclear. In this study, urea fertilizers were applied to paddy soils in a gradient of 100 (N100), 80 (N80), and 60 mg kg-1 (N60) concentrations. Flooding (W1) and 60% field holding capacity (W2) was set for each N fertilizer application to observe the effects of W × N patterns on soil properties and GHGs efflux through incubation experiments. The results showed that W significantly affected soil electrical conductivity and different N forms (i.e., alkali hydrolyzed N, ammonium N, nitrate N and microbial biomass N) contents. Soil organic carbon (C) content was reduced by 14.40% in W1N60 relative to W1N100, whereas microbial biomass C content was increased by 26.87%. Moreover, soil methane (CH4) fluxes were low in all treatments, with a range of 1.60-1.65 µg CH4 kg-1. Soil nitrous oxide (N2O) and carbon dioxide (CO2) fluxes were significantly influenced by W, N and W × N. Global warming potential was maintained at the lowest level in W1N60 treatment at 0.67 g CO2-eq kg-1, suggesting W1N60 as the preferred W × N pattern with high environmental impact. Our findings demonstrate that reduced N fertilization contributes to the effective mitigation of soil N2O and CO2 efflux by lowering the soil total N and organic C contents and regulating soil microbial biomass C and N.

Over-Reduction-Controlled Mixed-Valent Manganese Oxide with Tunable Mn2+/Mn3+ Ratio for High-Performance Asymmetric Supercapacitor with Enhanced Cycling Stability.

Manganese oxides composed of various valence states Mnx+ (x = 2, 3, and 4) have attracted wide attention as promising electrode materials for asymmetric supercapacitor. However, the poor electrical conductivity limited their performance and application. Appropriate regulation content of Mnx+ in mixed-valent manganese oxide can tune the electronic structure and further improve their conductivity and performance. Herein, we prepared manganese oxides with different Mn2+/Mn3+ ratios through an over-reduction (OR) strategy for tuning the internal electron structure of mixed-valent manganese, which could make these material oxides a good platform for researching the structure-property relationships. The Mn2+/Mn3+ ratio of manganese oxide could be precisely tuned from 0.6 to 1.7 by controlling the amount of reducing agent for manipulating the redox processes, where the manganese oxide electrode with the most appropriate Mn2+/Mn3+ ratio, as 1.65 (OR4) exhibits large capacitance (274 F g-1) and the assembling asymmetric supercapacitors by combining OR4 (positive) and the commercial activated carbon (as negative) achieved large 2.0 V voltage window and high energy density of 27.7 Wh kg-1 (power density of 500 W kg-1). The cycle lifespan of the OR4//AC could keep about 92.9% after 10 000-cycle tests owing to the Jahn-Teller distortion of the Mn(III)O6 octahedron, which is more competitive compared to other work. Moreover, a red-light-emitting diode (LED) can easily be lit for 15 min by two all-solid supercapacitor devices in a series.