Isolation and characterization of a cold-tolerant heterotrophic nitrification-aerobic denitrification bacterium and evaluation of its nitrogen-removal efficiency.

With a view toward addressing the poor efficiency with which nitrogen is removed from wastewater below 10 °C, in this study, we isolated a novel cold-tolerant heterotrophic nitrification-aerobic denitrification (HN-AD) bacterium from a wetland and characterized its nitrogen removal performance and nitrogen metabolic pathway. On the basis of 16S rRNA gene sequencing, this strain was identified as a species of Janthinobacterium, designated J1-1. At 8 °C, strain J1-1 showed excellent removal efficiencies of 89.18% and 68.18% for single-source NH4+-N and NO3--N, respectively, and removal efficiencies of 96.23% and 79.64% for NH4+-N and NO3--N, respectively, when supplied with mixed-source nitrogen. Whole-genome sequence analysis and successful amplification of the amoA, napA, and nirK functional genes related to nitrogen metabolism provided further evidence in support of the HN-AD capacity of strain J1-1. The deduced HN-AD metabolic pathway of the strain was NH4+-N→NH2OH→NO2--N→NO3--N→NO2--N→NO→N2O. In addition, assessments of NH4+-N removal under different conditions revealed the following conditions to be optimal for efficient removal: a temperature of 20 °C, pH of 7, shaking speed of 150 rpm, sodium succinate as a carbon source, and a C/N mass ratio of 16. Given its efficient nitrogen removal capacity at 8 °C, the J1-1 strain characterized in this study has considerable application potential in the treatment of low-temperature wastewater.

Bubbles-induced turbulence channel prediction mechanism based on machine vision in underwater wireless optical communication.

Bubbles-induced turbulence poses a significant challenge to the stability of underwater wireless optical communication (UWOC) system. Existing methods for understanding channel characteristics rely on the pilot information from the feed-back channel, which are ineffective and inaccurate due to the rapidly changing nature of the underwater channel. We propose a machine-vision-based channel prediction mechanism which contains three modules of motion judgment module, image processing module and scintillation index (SI) prediction module. The mechanism captures images of bubbles and calculates the bubble density. Subsequently, a relational function is applied to acquire the predicted SI which quantifies the impacts of bubbles on the channel. Experimental results validate the effectiveness of the proposed mechanism.

Upregulation of MCL-1 by LUCAT1 through interacting with SRSF1 promotes the migration and invasion in non-small cell lung carcinoma.

The onset of non-small cell lung carcinoma (NSCLC) still be in the fog. LUCAT1 is potentially capable of modulating MCL-1-involved NSCLC pathogenesis via targeting SRSF1. Also, MCL-1 can regulate Wnt/ß-catenin pathway to affect the tumorigenesis of NSCLC. Thus, this paper aims to uncover an intriguing and novel role of LUCAT1/SRSF1/MCL-1 axis in NSCLC based on Wnt/ß-catenin pathway. A549 and NCI-H1650, two cell lines of NSCLC, were used to mimic NSCLC in vitro. MCL-1 siRNA (si-MCL-1) and LUCAT1 siRNA (si-LUCAT1) were used to downregulate MCL-1 and LUCAT1 in NSCLC cells, respectively. The overexpression vector of SRSF1 based on pcDNA 3.1 was constructed to upregulate SRSF1 expression. 40 µM SKL2001 was used to activate Wnt/ß-catenin pathway. Transwell assay was used for migrative and invasive tests. The effect of LUCAT1 on tumor metastasis was verified in nude mice. MCL-1 downregulation led to the decrease of EMT, invasion, and migration in NSCLC, while Wnt/ß-catenin pathway agonist partially reversed the effects of MCL-1 downregulation. Mechanistic investigations revealed that LUCAT1 and MCL-1 mRNA were enriched in SRSF1; LUCAT1 silence decreased MCL-1, whereas SRSF1 enhancement elevated MCL-1; Importantly, SRSF1 overexpression significantly reversed MCL-1 alteration due to LUCAT1 silence. In NSCLC cells, SRSF1 overexpression offset the si-LUCAT1-induced changes, and si-MCL-1 reversed the SRSF1-induced cellular changes. Further, LUCAT1 inhibition reduced lung metastasis of cancer cells. LUCAT1 can interact with SRSF1 to regulate MCL-1 expression that targets the Wnt/ß-catenin pathway-mediated NSCLC cell migration, invasion, and EMT.

Synthesis and Multi-Stimuli-Responsive Behavior of Poly(N,N-dimethylaminoethyl methacrylate) Spherical Brushes under Different Modes of Confinement in Solution.

We report the synthesis and solution behavior of photo-, temperature-, pH-, and ion-responsive weak polyelectrolyte spherical brushes under different modes of confinement. The spherical brushes were prepared by copolymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and 7-(2-methacryloyloxyethoxy)-4-methylcoumarin anchored to silica nanoparticles via surface-initiated atom transfer radical polymerization. The photo-cross-linking and reversibility of the nanoparticle-attached coumarin entities are detected by UV-visible spectroscopy and dynamic light scattering (DLS). The cross-linking density of poly(DMAEMA) (i.e., PDMAEMA) brushes could be easily controlled by alternating irradiation at wavelengths of 365 and 254 nm. Moreover, solution behavior under different pH levels and ionic strengths is systematically investigated in the PDMAEMA brush-polyelectrolyte chains confined only by a hard core, the cross-linked PDMAEMA brush-polyelectrolyte chains confined by a hard core and cross-linking points, and the corresponding hollow nanocapsules after removal of silica by etching-polyelectrolyte chains confined only by cross-linking points. These three models represent the different modes of confinement. DLS results indicate that the volume phase transition temperatures of the three models shift to lower temperatures with the increase in pH. The highest temperature is afforded to phase transition for hollow nanocapsules in solution, followed by the cross-linked PDMAEMA brushes. The hydrodynamic radius of the polyelectrolyte brush systems obviously decreases with the increase in ionic strength of the solution when adjusted by NaCl.

U-NTCA: nnUNet and nested transformer with channel attention for corneal cell segmentation.

Background: Automatic segmentation of corneal stromal cells can assist ophthalmologists to detect abnormal morphology in confocal microscopy images, thereby assessing the virus infection or conical mutation of corneas, and avoiding irreversible pathological damage. However, the corneal stromal cells often suffer from uneven illumination and disordered vascular occlusion, resulting in inaccurate segmentation. Methods: In response to these challenges, this study proposes a novel approach: a nnUNet and nested Transformer-based network integrated with dual high-order channel attention, named U-NTCA. Unlike nnUNet, this architecture allows for the recursive transmission of crucial contextual features and direct interaction of features across layers to improve the accuracy of cell recognition in low-quality regions. The proposed methodology involves multiple steps. Firstly, three underlying features with the same channel number are sent into an attention channel named gnConv to facilitate higher-order interaction of local context. Secondly, we leverage different layers in U-Net to integrate Transformer nested with gnConv, and concatenate multiple Transformers to transmit multi-scale features in a bottom-up manner. We encode the downsampling features, corresponding upsampling features, and low-level feature information transmitted from lower layers to model potential correlations between features of varying sizes and resolutions. These multi-scale features play a pivotal role in refining the position information and morphological details of the current layer through recursive transmission. Results: Experimental results on a clinical dataset including 136 images show that the proposed method achieves competitive performance with a Dice score of 82.72% and an AUC (Area Under Curve) of 90.92%, which are higher than the performance of nnUNet. Conclusion: The experimental results indicate that our model provides a cost-effective and high-precision segmentation solution for corneal stromal cells, particularly in challenging image scenarios.

Diversity of soil faunal community as influenced by crop straw combined with different synthetic fertilizers in upland purple soil.

Soil fauna play a crucial role in sustaining agro-ecosystem functions. Crop straw is recommended for application to agricultural fields to improve soil quality. However, the effects of crop straw combined with different synthetic fertilizers on the soil faunal community remain unclear, and knowledge regarding purple soil is limited. Using the conserved cytochrome c oxidase I (COI) gene as markers, we examined the responses of the soil faunal community to different fertilization in upland purple soil of southwestern China. The accuracy of the morphological and molecular methods in characterizing soil nematodes was compared. Our results showed that different fertilization treatments significantly changed the soil faunal community structure (Adonis test, R2 = 0.43, P = 0.011). Sixteen biomarkers were identified according to LEfSe (linear discriminant analysis effect size). The diversity and species number of soil fauna were closely related to soil organic matter (SOM) and total phosphorus (TP) (P < 0.05). This study indicates that crop straw return can improve the soil fertility and diversity of soil fauna in purple soil. Additionally, the morphological approach and molecular method based on the COI gene can be considered as complementary approaches in characterizing soil nematode community.

The contributions of ammonia oxidizing bacteria and archaea to nitrification-dependent N2O emission in alkaline and neutral purple soils.

Nitrification is believed to be one of the primary processes of N2O emission in the agroecological system, which is controlled by soil microbes and mainly regulated by soil pH, oxygen content and NH4+ availability. Previous studies have proved that the relative contributions of ammonia oxidizing bacteria (AOB) and archaea (AOA) to N2O production were varied with soil pH, however, there is still no consensus on the regulating mechanism of nitrification-derived N2O production by soil pH. In this study, 1-octyne (a selective inhibitor of AOB) and acetylene (an inhibitor of AOB and AOA) were used in a microcosm incubation experiment to differentiate the relative contribution of AOA and AOB to N2O emissions in a neutral (pH = 6.75) and an alkaline (pH = 8.35) soils. We found that the amendment of ammonium (NH4+) observably stimulated the production of both AOA and AOB-related N2O and increased the ammonia monooxygenase (AMO) gene abundances of AOA and AOB in the two test soils. Among which, AOB dominated the process of ammonia oxidation in the alkaline soil, contributing 70.8% of N2O production derived from nitrification. By contrast, the contribution of AOA and AOB accounted for about one-third of nitrification-related N2O in acidic soil, respectively. The results indicated that pH was a key factor to change abundance and activity of AOA and AOB, which led to the differentiation of derivation of N2O production in purple soils. We speculate that both NH4+ content and soil pH mediated specialization of ammonia-oxidizing microorganisms together; and both specialization results and N2O yield led to the different N2O emission characteristics in purple soils. These results may help inform the development of N2O reduction strategies in the future.

Phase behavior of poly(sulfobetaine methacrylate)-grafted silica nanoparticles and their stability in protein solutions.

Biocompatible and zwitterionic poly(sulfobetaine methacrylate) (PSBMA) was grafted onto the surface of initiator-modified silica nanoparticles via surface-initiated atom transfer radical polymerization. The resultant samples were characterized via nuclear magnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. Their molecular weights and molecular weight distributions were determined via gel permeation chromatography after the removal of silica by etching. Moreover, the phase behavior of these polyzwitterionic-grafted silica nanoparticles in aqueous solutions and stability in protein/PBS solutions were systematically investigated. Dynamic light scattering and UV-visible spectroscopy results indicate that the silica-g-PSBMA nanoparticles exhibit an upper critical solution temperature (UCST) in aqueous solutions, which can be controlled by varying the PSBMA molecular weight, ionic strength, silica-g-PSBMA nanoparticle concentration, and solvent polarity. The UCSTs shift toward high temperatures with increasing PSBMA molecular weight and silica-g-PSBMA nanoparticle concentration. However, increasing the ionic strength and solvent polarity leads to a lowering of the UCSTs. The silica-g-PSBMA nanoparticles are stable for at least 72 h in both negative and positive protein/PBS solutions at 37 °C. The current study is crucial for the translation of polyzwitterionic solution behavior to surfaces to exploit their diverse properties in the development of new, smart, and responsive coatings.

Reaction Mechanism of the Sn2Fe Anode in Lithium-Ion Batteries.

Sn2Fe anode materials were synthesized by a solvothermal route, and their electrochemical performance and reaction mechanism were evaluated. The structural evolution in the first two lithium cycles was investigated by X-ray absorption spectroscopy (XAS), synchrotron X-ray diffraction (XRD), and magnetic studies. In the first cycle, progressive alloying of Sn with Li accompanied by metallic iron displacement occurs upon lithiation, and the delithiation proceeds by Li x Sn dealloying and recovery of the Sn2Fe phase. In the second cycle, both XRD and XAS identify Li-Sn alloying at earlier lithiation stages than in the first cycle, with low-Li-content alloys evident in the beginning of the lithiation process. In the fully lithiated state, XAS analysis reveals higher coordination numbers in both the Li x Sn and Fe phases, which points toward more complete reaction and higher crystallinity of the products. Upon second delithiation, the Sn2Fe phase is generally reformed as evidenced by XRD. However, XAS indicates somewhat reduced Sn-Fe coordination and shorter Fe-Fe distance, which indicates incomplete reconversion and metallic Fe retention, which is also evident in the magnetic studies. Thus, a combination of long-range (XRD, magnetic) and local (XAS) techniques has revealed differences between the first and the second Li cycles relevant to the understanding of the capacity fading mechanisms.

The Anode Challenge for Lithium-Ion Batteries: A Mechanochemically Synthesized Sn-Fe-C Composite Anode Surpasses Graphitic Carbon.

Carbon-based anodes are the key limiting factor in increasing the volumetric capacity of lithium-ion batteries. Tin-based composites are one alternative approach. Nanosized Sn-Fe-C anode materials are mechanochemically synthesized by reducing SnO with Ti in the presence of carbon. The optimum synthesis conditions are found to be 1:0.25:10 for initial ratio of SnO, Ti, and graphite with a total grinding time of 8 h. This optimized composite shows excellent extended cycling at the C/10 rate, delivering a first charge capacity as high as 740 mAh g-1 and 60% of which still remained after 170 cycles. The calculated volumetric capacity significantly exceeds that of carbon. It also exhibits excellent rate capability, delivering volumetric capacity higher than 1.6 Ah cc-1 over 140 cycles at the 1 C rate.

The influence of N-fertilization regimes on N2O emissions and denitrification in rain-fed cropland during the rainy season.

The effects of nitrogen fertilization regimes on N2O emissions and denitrification rates were evaluated by in situ field incubation experiments with intact soil cores and the acetylene block technique. Intact soil cores were collected from long-term field experiments involving several N fertilization regimes, including single synthetic N fertilizer (N), organic manure (OM), synthetic N, P, K fertilizer (NPK), organic manure with synthetic fertilizer (OMNPK), crop straw residue with synthetic fertilizer (SRNPK) and no nitrogen fertilizer (NF). N2O was sampled from the head space of the cylinders to determine the daily N2O emission and denitrification rate. The results showed that the N2O emissions were greatly influenced by the specific fertilization regime even when the same nitrogen rate was applied. The mean N2O emissions and denitrification rates from the N, OM, NPK, OMNPK and SRNPK treatment were 2.22, 2.66, 1.94, 2.53, 1.67 and 4.63, 5.96, 4.15, 5.41, 3.65 mg per m(2) per day, respectively. The application of OM significantly increased the N2O emission and denitrification compared to the application of NPK because of the high soil organic carbon (SOC) content of OM. However, SRNPK increased the SOC content and decreased the N2O emissions significantly compared to the OM and OMNPK treatments because the addition of crop straw with a high C/N ratio to soil with a low inorganic N content induced N immobilization. The contents of soil nitrate and ammonium were the main limiting factors for N2O emissions in a positive regression as follows: Ln (N2O) = 2.511 + 1.258 × Ln ([NH4(+)] + [NO3(-)]). Crop straw residue combined with synthetic fertilizer is recommended as an optimal strategy for mitigating N2O emissions and denitrification-induced N loss in rain-fed croplands.

A long-term field experiment of soil transplantation demonstrating the role of contemporary geographic separation in shaping soil microbial community structure.

The spatial patterns of microbial communities are largely determined by the combined effects of historical contingencies and contemporary environmental disturbances, but their relative importance remains poorly understood. Empirical biogeographic data currently available are mostly based on the traditional method of observational survey, which typically involves comparing indigenous microbial communities across spatial scales. Here, we report a long-term soil transplantation experiment, whereby the same two soils (red Acrisol and purple Cambisol from Yingtan) were placed into two geographic locations of ∼1000 km apart (i.e., Yingtan in the mid-subtropical region and Fengqiu in warm-temperate region; both located in China). Twenty years after the transplantation, the resulting soil microbial communities were subject to high-throughput 454 pyrosequencing analysis of 16S and 18S rRNA genes. Additionally, bacteria and archaea involved in nitrogen cycling were estimated using clone library analysis of four genes: archaeal amoA, bacterial amoA,nirK, and nifH. Data of subsequent phylogenetic analysis show that bacteria, fungi, and other microbial eukaryotes, as well as the nitrogen cycling genes, are grouped primarily by the factor of geographic location rather than soil type. Moreover, a shift of microbial communities toward those in local soil (i.e., Chao soil in Fengqiu) has been observed. The results thus suggest that the historical effects persistent in the soil microbial communities can be largely erased by contemporary disturbance within a short period of 20 years, implicating weak effects of historical contingencies on the structure and composition of microbial communities in the soil.