The calculated electronic and optical properties of ß-Ga2O3 based on the first principles.

INTRODUCTION: The electronic and optical properties of ß-Ga2O3 have been investigated by CASTEP using first principles. It is found that ß-Ga2O3 has an indirect band gap and the conduction band base is located at the Γ point. The stability of ß-Ga2O3 is demonstrated by the calculation of elastic constants, and the ductility of ß-Ga2O3 is demonstrated by the ratio of Poisson's ratio to shear modulus. The optical property analysis shows that ß-Ga2O3 has a high absorption capacity in the ultraviolet region, but a low absorption capacity in visible and infrared light. CONTEXT: The structure, optical, and electronic properties of ß-Ga2O3 are calculated and analyzed based on first-principles calculation. The optimized structures of ß-Ga2O3 are in good agreement with previously studied. In this paper, the elastic, electronic, and optical properties of ß-Ga2O3 are calculated. METHODS: The CASTEP code was employed to execute these calculations in the present work, where the exchange-correlation interactions were treated in the generalized gradient approximation (GGA) using the Perdew-Burke-Ernzerhof (PBE) functional in the geometry optimizations and electronic and elastic properties.

Fortified Dual-Spectral Overlap with Enhanced Colorimetric/Fluorescence Dual-Response Immunochromatography for On-Site Bimodal-Type Gentamicin Monitoring.

Immunochromatography (ICA) remains untapped toward enhanced sensitivity and applicability for fulfilling the nuts and bolts of on-site food safety surveillance. Herein, we report a fortified dual-spectral overlap with enhanced colorimetric/fluorescence dual-response ICA for on-site bimodal-type gentamicin (Gen) monitoring by employing polydopamine (PDA)-coated AuNPs (APDA) simultaneously serving as a colorimetric reporter and a fluorescence quencher. Availing of the enhanced colorimetric response that originated from the PDA layer, the resultant APDA exhibits less required antibody and immunoprobes in a single immunoassay, which facilitates improved antibody utilization efficiency and immuno-recognition in APDA-ICA. Further integrated with the advantageous features of fortified excitation and emission dual-spectral overlap for the Arg/ATT-AuNCs, this APDA-ICA with a "turn on/off" pattern achieves the visual limits of detection of 1.0 and 0.5 ng mL-1 for colorimetric and fluorescence patterns (25- and 50-fold lower than standard AuNPs-ICA). Moreover, the excellent self-calibration and satisfactory recovery of 79.03-118.04% were shown in the on-site visual colorimetric-fluorescence analysis for Gen in real environmental media (including real river water, an urban aquaculture water body, an aquatic product, and an animal byproduct). This work provides the feasibility of exploiting fortified dual-spectral overlap with an enhanced colorimetric/fluorescence dual response for safeguarding food safety and public health.

Effect of tremella polysaccharides on the quality of collagen jelly: insight into the improvement of the gel properties and the antioxidant activity of yak skin gelatin.

BACKGROUND: The present study aimed to investigate the effects of tremella polysaccharides on the gel properties and antioxidant activity of yak skin gelatin with a view to improving the quality of collagen jellies. The preparation of composite gels were performed by yak skin gelatin (66.7 mg mL-1) and tremella polysaccharides with different concentrations (0, 2, 4, 6, 8 mg mL-1), and finally the collagen jelly was prepared by composite gel (yak skin gelatin: 66.7 mg mL-1; tremella polysaccharides:6 mg mL-1) with the best performance. RESULTS: Tremella polysaccharides not only improved the hardness, springiness, gel strength, water holding capacity and melting temperature of yak skin gelatin, but also enhanced the composite gel's scavenging activity against ABTS radicals, DPPH radicals, O2 and OH radicals. The filling of tremella polysaccharides into the gelatin network increased the number of crosslinking sites inside the gel, which resulted in the gel network structure becoming dense and orderly. The gel particles became finer and more uniform, and the thermal stability was improved. Furthermore, the sensory score of commercially available gelatin jelly decreased more rapidly during storage compared to the composite gel jelly. CONCLUSION: The gel properties and antioxidant activity of yak skin gelatin were improved by adding tremella polysaccharides, and then the quality and storage properties of the jelly were improved, which also provided technical reference for the development of functional gel food. © 2024 Society of Chemical Industry.

Machine-Learning-Assisted Aggregation-Induced Emissive Nanosilicon-Based Sensor Array for Point-of-Care Identification of Multiple Foodborne Pathogens.

How timely identification and determination of pathogen species in pathogen-contaminated foods are responsible for rapid and accurate treatments for food safety accidents. Herein, we synthesize four aggregation-induced emissive nanosilicons with different surface potentials and hydrophobicities by encapsulating four tetraphenylethylene derivatives differing in functional groups. The prepared nanosilicons are utilized as receptors to develop a nanosensor array according to their distinctive interactions with pathogens for the rapid and simultaneous discrimination of pathogens. By coupling with machine-learning algorithms, the proposed nanosensor array achieves high performance in identifying eight pathogens within 1 h with high overall accuracy (93.75-100%). Meanwhile, Cronobacter sakazakii and Listeria monocytogenes are taken as model bacteria for the quantitative evaluation of the developed nanosensor array, which can successfully distinguish the concentration of C. sakazakii and L. monocytogenes at more than 103 and 102 CFU mL-1, respectively, and their mixed samples at 105 CFU mL-1 through the artificial neural network. Moreover, eight pathogens at 1 × 104 CFU mL-1 in milk can be successfully identified by the developed nanosensor array, indicating its feasibility in monitoring food hazards.

MSMTSeg: Multi-Stained Multi-Tissue Segmentation of Kidney Histology Images via Generative Self-Supervised Meta-Learning Framework.

Accurately diagnosing chronic kidney disease requires pathologists to assess the structure of multiple tissues under different stains, a process that is timeconsuming and labor-intensive. Current AI-based methods for automatic structure assessment, like segmentation, often demand extensive manual annotation and focus on single stain domain. To address these challenges, we introduce MSMTSeg, a generative self-supervised meta-learning framework for multi-stained multi-tissue segmentation in renal biopsy whole slide images (WSIs). MSMTSeg incorporates multiple stain transform models for style translation of inter-stain domains, a self-supervision module for obtaining pre-trained models with the domain-specific feature representation, and a meta-learning strategy that leverages generated virtual data and pre-trained models to learn the domain-invariant feature representation across multiple stains, thereby enhancing segmentation performance. Experimental results demonstrate that MSMTSeg achieves superior and robust performance, with mDSC of 0.836 and mIoU of 0.718 for multiple tissues under different stains, using only one annotated training sample for each stain. Our ablation study confirms the effectiveness of each component, positioning MSMTSeg ahead of classic advanced segmentation networks, recent few-shot segmentation methods, and unsupervised domain adaptation methods. In conclusion, our proposed few-shot cross-domain technology offers a feasible and cost-effective solution for multi-stained renal histology segmentation, providing convenient assistance to pathologists in clinical practice. The source code and conditionally accessible data are available at https://github.com/SnowRain510/MSMTSeg.

Association of urinary calcium excretion with chronic kidney disease in patients with type 2 diabetes.

PURPOSE: Herein, we investigated the correlation between urinary calcium excretion (UCaE) and chronic kidney disease (CKD) in patients with type 2 diabetes mellitus (T2DM). METHODS: From August 2018 to January 2023, a total of 2031 T2DM patients providing 24-h urine samples were included in the final analyses. Patients were separated into four cohorts, based on the UCaE quartiles. We then analyzed renal functional indicators like estimated glomerular filtration rate (eGFR) and urinary albumin excretion (UAE) among the four groups. Lastly, we utilized multivariable logistic regression models to investigate the correlation between UCaE and CKD. RESULTS: After adjusting for confounding factors, we observed a decreasing trend in CKD prevalence (36.3%, 13.0%, 7.5%, and 6.6%, respectively, P < 0.001) across the UCaE quartiles. Albuminuria (55.5% vs. 40.0%, 36.5%, 37.4%) and macroalbuminuria prevalence (20.0% vs. 9.3%, 5.2%, 5.7%) in the lowest quartile were markedly elevated, compared to the remaining three quartiles (P < 0.001). Meanwhile, the eGFR level (P < 0.001) showed a clearly increasing trend across the UCaE quartiles, and patients with moderate-to-severe decreases in eGFR levels (with cutoff limits at 30-59, 15-30, and < 15 mL/min/1.73m2) were mostly found in the lowest quartile (P < 0.001). Logistic regression analysis revealed that patients in the lowest quartile experienced an enhanced prevalence of CKD, relative to those in the highest quartile (odds ratio: 5.90, 95% confidence interval: 3.60-9.67, P < 0.001). CONCLUSION: Decreased UCaE was independently associated with the CKD prevalence in T2DM patients.

Bioretention Design Modifications Increase the Simulated Capture of Hydrophobic and Hydrophilic Trace Organic Compounds.

Stormwater rapidly moves trace organic contaminants (TrOCs) from the built environment to the aquatic environment. Bioretention cells reduce loadings of some TrOCs, but they struggle with hydrophilic compounds. Herein, we assessed the potential to enhance TrOC removal via changes in bioretention system design by simulating the fate of seven high-priority stormwater TrOCs (e.g., PFOA, 6PPD-quinone, PAHs) with log KOC values between -1.5 and 6.74 in a bioretention cell. We evaluated eight design and management interventions for three illustrative use cases representing a highway, a residential area, and an airport. We suggest two metrics of performance: mass advected to the sewer network, which poses an acute risk to aquatic ecosystems, and total mass advected from the system, which poses a longer-term risk for persistent compounds. The optimized designs for each use case reduced effluent loadings of all but the most polar compound (PFOA) to <5% of influent mass. Our results suggest that having the largest possible system area allowed bioretention systems to provide benefits during larger events, which improved performance for all compounds. To improve performance for the most hydrophilic TrOCs, an amendment like biochar was necessary; field-scale research is needed to confirm this result. Our results showed that changing the design of bioretention systems can allow them to effectively capture TrOCs with a wide range of physicochemical properties, protecting human health and aquatic species from chemical impacts.

Precise Spectral Overlap-Based Donor-Acceptor Pair for a Sensitive Traffic Light-Typed Bimodal Multiplexed Lateral Flow Immunoassay.

Bimodal-type multiplexed immunoassays with complementary mode-based correlation analysis are gaining increasing attention for enhancing the practicability of the lateral flow immunoassay (LFIA). Nonetheless, the restriction in visually indistinguishable multitargets induced by a single fluorescent color and difficulty in single acceptor ineffectual fluorescence quenching due to the various spectra of multiple different donors impede the further execution of colorimetric-fluorescence bimodal-type multiplexed LFIAs. Herein, the precise spectral overlap-based donor-acceptor pair construction strategy is proposed by regulating the size of the nanocore, coating it with an appropriate nanoshell, and selecting a suitable fluorescence donor with distinct colors. By in situ coating Prussian blue nanoparticles (PBNPs) on AuNPs with a tunable size and absorption spectrum, the resultant APNPs demonstrate efficient fluorescence quenching ability, higher colloidal stability, remarkable colorimetric intensity, and an enhanced antibody coupling efficiency, all of which facilitate highly sensitive bimodal-type LFIA analysis. Following integration with competitive-type immunoreaction, this precise spectral overlap-supported spatial separation traffic light-typed colorimetric-fluorescence dual-response assay (coined as the STCFD assay) with the limits of detection of 0.013 and 0.152 ng mL-1 for ractopamine and clenbuterol, respectively, was proposed. This work illustrates the superiority of the rational design of a precise spectral overlap-based donor-acceptor pair, hinting at the enormous potential of the STCFD assay in the point-of-care field.

A data-driven analysis to discover research hotspots and trends of technologies for PFAS removal.

The frequent detection of persistent per- and polyfluoroalkyl substances (PFAS) in organisms and environment coupled with surging evidence for potential detrimental impacts, have attracted widespread attention throughout the world. In order to reveal research hotspots and trends of technologies for PFAS removal, herein, we performed a data-driven analysis of 3975 papers and 436 patents from Web of Science Core Collection and Derwent Innovation Index databases up to 2023. The results showed that China and the USA led the way in the research of PFAS removal with outstanding contributions to publications. The progression generally transitioned from accidental discovery of decomposition, to experimentation with removal effects and mechanisms of existing methods, and finally to enhanced defluorination and mechanism-driven design approaches. The keywords co-occurrence network and technology classification together revealed the main knowledge framework, which was constructed and correlated through contaminants, substrates, materials, processes and properties. Moreover, adsorption was demonstrated to be the dominant removal process among the current studies. Subsequently, we concluded the principles, advances and drawbacks of enrichment and separation, biological methods, advanced oxidation and reduction processes. Further exploration indicated the hotspots such as alternatives and precursors for PFAS ("genx": 1.258, "f-53b": 0.337), degradable mineralization technologies ("photocatalytic degrad": 0.529, "hydrated electron": 0.374), environment-friendly remediation technologies ("phytoremedi": 0.939, "constructed wetland": 0.462) and combination with novel materials ("metal-organic framework": 1.115, "layered double hydroxid": 0.559) as well as computer science ("molecular dynamics simul": 0.559, "machine learn"). Furthermore, the future direction of technological innovation might lie in high-performance processes that minimize secondary pollution, the development of recyclable and renewable treatment agents, and collaborative control strategies for multiple pollutants. Overall, this study offers comprehensive and objective review for researchers and industry professionals in this field, enabling rapid access to knowledge guidance and insights into research frontiers.

A "solo-solvent de novo liquid-phase" method for synthesizing sulfide solid electrolyte Li6PS5Cl.

We report a "solo-solvent de novo liquid-phase" method of synthesizing a highly-favored sulfide electrolyte (Li6PS5Cl) for developing all-solid-state lithium batteries. The key chemistry for such a successful method is that tetrahydropyrrole enables in situ synthesis of the critical precursor Li2S from cheap and air-stable precursors of lithium chloride and sodium sulfide.

Perovskite Nanocrystals: Superior Luminogens for Food Quality Detection Analysis.

With the global limited food resources receiving grievous damage from frequent climate changes and ascending global food demand resulting from increasing population growth, perovskite nanocrystals with distinctive photoelectric properties have emerged as attractive and prospective luminogens for the exploitation of rapid, easy operation, low cost, highly accurate, excellently sensitive, and good selective biosensors to detect foodborne hazards in food practices. Perovskite nanocrystals have demonstrated supreme advantages in luminescent biosensing for food products due to their high photoluminescence (PL) quantum yield, narrow full width at half-maximum PL, tunable PL in the entire visible spectrum, easy preparation, and various modification strategies compared with conventional semiconductors. Herein, we have carried out a comprehensive discussion concerning perovskite nanocrystals as luminogens in the application of high-performance biosensing of foodborne hazards for food products, including a brief introduction of perovskite nanocrystals, perovskite nanocrystal-based biosensors, and their application in different categories of food products. Finally, the challenges and opportunities faced by perovskite nanocrystals as superior luminogens were proposed to promote their practicality in the future food supply.

Evaluation of cerebrovascular reactivity in moyamoya disease using oxygen-dependent magnetic resonance imaging.

Moyamoya disease (MMD) is a rare cerebrovascular disorder marked by progressive stenosis of the internal carotid arteries. Assessing cerebral hemodynamics, specifically cerebrovascular reactivity (CVR), is vital for MMD management and prognosis. In this study, fMRI was performed in a prospective cohort of 47 patients with MMD and 32 healthy controls to investigate its utility in evaluating CVR and to explore the influence of cerebral posterior circulation compensation on CVR in MMD. The regions where the CVR values of participants with MMD were lower than those of healthy controls were primarily concentrated in the frontal, parietal, and temporal lobes (p < 0.05). In certain regions mainly supplied by posterior circulation, the CVR values of compensatory-normal subgroup tended to exceed those of compensatory-poor subgroup. fMRI can detect a significant decrease in CVR values in patients with MMD compared to healthy controls. Compensation for the posterior cerebral circulation may affect cerebrovascular reactivity.

Enhanced sandwich immunoassay based on bivalent nanobody as an efficient immobilization approach for foodborne pathogens detection.

BACKGROUND: Nanobodies (Nbs), which consist of only antigen-binding domains of heavy chain antibodies, have been used in a various range of applications due to their excellent properties. Nevertheless, the size of Nbs is so small that their antigen binding sites may be sterically hindered after random fixation as capture antibodies, thus leading to poor detection performance in immunoassays. To address this problem, we have focused on the multivalent modification of Nbs, wanted to retain the advantage of good stability through enlarging the size of Nbs to a certain extent, while improve its affinity and reduce its influence by spatial orientation. RESULTS: Here, we designed homo- and heterodimeric Nbs based on Nb413 and Nb422 which recognize different epitopes of Salmonella. The affinity of engineered bivalent nanobodies for S. Enteritidis were 2 orders of magnitude higher compared to monovalent Nbs and low to sub-nM KD, as calculated by Scatchard analysis. To further explore the potential of bivalent Nbs for the detection of Salmonella, we established a sandwich ELISA based on bivalent and phage-displayed Nbs (BNb-ELISA) for multiplex Salmonella determination. Compared with monovalent Nb-based ELISA, the limit of detection (LOD) of the BNb-ELISA was shown to increase 7.5-fold to 2.364 × 103 CFU mL-1 for S. Enteritidis. In addition, the feasibility of this approach for S. Enteritidis detection in real samples was evaluated, with recoveries ranging from 73.0 % to 125.6 % and coefficients of variation (CV) below 7.68 %. SIGNIFICANCE AND NOVELTY: In this study, we developed for the first time bivalent Nbs against Salmonella and examined their improved affinity and impact on the performance of ELISA assay. It confirmed the high binding affinity and good ability of dimeric Nbs to reduce the occupation of the binding sites of immobilized antibodies. Thus, the multivalent modification of Nbs was demonstrated to be a promising means to enhance the performance of Nbs-based immunoassays for foodborne pathogens.

Optimizing waste molasses utilization to enhance electron transfer via micromagnetic carriers: Mechanisms and high-nitrate wastewater denitrification performance.

The biological denitrification of high-nitrate wastewater (HNW) is primarily hindered by insufficient carbon sources and excessive nitrite accumulation. In this study, micromagnetic carriers with varying micromagnetic field (MMF) strengths (0.0, 0.3, 0.6, 0.9 mT) were employed to enhance the denitrification of HNW using waste molasses (WMs) as a carbon source. The results revealed that 0.6 mT MMF significantly improved the total nitrogen removal (TN) efficiency at 96.3%. A high nitrate (NO3--N) removal efficiency at 99.3% with a low nitrite (NO2--N) accumulation at 25.5 mg/L was achieved at 0.6 mT MMF. The application of MMF facilitated the synthesis of adenosine triphosphate (ATP) and stimulated denitrifying enzymes (e.g., nitrate reductase (NAR), nitrite reductase (NIR), and nitric oxide reductase (NOR)), which thereby promoting denitrification. Moreover, the effluent chemical oxygen demand (COD), tryptophan and fulvic-like substances exhibited their lowest levels at 0.6 mT MMF. Analysis through 16S ribosomal ribonucleic acid gene sequencing indicated a significant enrichment of denitrifying bacteria including Castellaniella Klebsiella under the influence of MMF. Besides, the proliferation of Acholeplasma, Klebsiella and Proteiniphilum at 0.6 mT MMF promoted the hydrolysis and acidification of WMs. This study offers new insights into the enhanced utilization of WMs and the denitrification of HNW through the application of MMF.

Weak magnetic carriers reduce nitrite accumulation and boost denitrification at high nitrate concentrations by enriching functional bacteria and enhancing electron transfer.

Biological denitrification is the dominant method for NO3- removal from wastewater, while high NO3- leads to NO2- accumulation and inhibits denitrification performance. In this study, different weak magnetic carriers (0, 0.3, 0.6, 0.9 mT) were used to enhance biological denitrification at NO3- of 50-2400 mg/L. The effect of magnetic carriers on the removal and mechanism of denitrification of high NO3- was investigated. The results showed that 0.6 and 0.9 mT carriers significantly enhanced the TN removal efficiency (>99%) and reduced the accumulation of NO2- (by > 97%) at NO3- of 1200-2400 mg/L 0.6 and 0.9 mT carriers stimulated microbial electron transport by improving the abundances of coenzyme Q-cytochrome C reductase (by 4.44-23.30%) and cytochrome C (by 2.90-16.77%), which contributed to the enhanced elimination of NO3- and NO2-. 0.6 and 0.9 mT carriers increased the activities of NAR (by 3.74-37.59%) and NIR (by 5.01-8.24%). The abundance of narG genes in 0.6 and 0.9 mT was 1.47-2.35 and 1.38-1.75 times that of R1, respectively, and the abundance of nirS genes was 1.49-2.83 and 1.55-2.39 times that of R1, respectively. Denitrifying microorganisms, e.g., Halomonas, Thauera and Pseudomonas were enriched at 0.6 and 0.9 mT carriers, which benefited to the advanced denitrification performance. This study suggests that weak magnetic carriers can help to enhance the biological denitrification of high NO3- wastewater.

Liuwei Dihuang pills attenuate ovariectomy-induced bone loss by alleviating bone marrow mesenchymal stem cell (BMSC) senescence via the Yes-associated protein (YAP)-autophagy axis.

CONTEXT: Liuwei Dihuang pill (LWDH) has been used to treat postmenopausal osteoporosis (PMOP). OBJECTIVE: To explore the effects and mechanisms of action of LWDH in PMOP. MATERIALS AND METHODS: Forty-eight female Sprague-Dawley rats were divided into four groups: sham-operated (SHAM), ovariectomized (OVX), LWDH high dose (LWDH-H, 1.6 g/kg/d) and LWDH low dose (LWDH-L, 0.8 g/kg/d); the doses were administered after ovariectomy via gavage for eight weeks. After eight weeks, the bone microarchitecture was evaluated. The effect of LWDH on the differentiation of bone marrow mesenchymal stem cells (BMSCs) was assessed via osteogenesis- and lipogenesis-induced BMSC differentiation. The senescence-related biological indices were also detected using senescence staining, cell cycle analysis, quantitative real-time polymerase chain reaction and western blotting. Finally, the expression levels of autophagy-related proteins and Yes-associated protein (YAP) were evaluated. RESULTS: LWDH-L and LWDH-H significantly modified OVX-induced bone loss. LWDH promoted osteogenesis and inhibited adipogenesis in OVX-BMSCs. Additionally, LWDH decreased the positive ratio of senescence OVX-BMSCs and improved cell viability, cell cycle, and the mRNA and protein levels of p53 and p21. LWDH upregulated the expression of autophagy-related proteins, LC3, Beclin1 and YAP, in OVX-BMSCs and downregulated the expression of p62. DISCUSSION AND CONCLUSIONS: LWDH improves osteoporosis by delaying the BMSC senescence through the YAP-autophagy axis.

One new prenylated flavonoid with cytotoxic activity from Epimedium brevicornu maxim.

One previously undescribed prenylated flavonoid (1) and three known ones (2-4) were isolated from leaves of Epimedium brevicornu maxim. Their structures were determined through extensive spectroscopic analysis and comparison with the NMR data in the literature. Compound 1 showed a moderate cytotoxicity with an IC50 value of 18.7 µM, while known compounds 2 and 3 elicited weak cytotoxicities with IC50 values of 29.2 and 32.8 µM against Lewis Lung cancer cells (LLC cells), respectively.

Enhancing Oriented Immobilization Efficiency: A One-for-Two Organism-Bispecific Nanobody Scaffold for Highly Sensitive Detection of Foodborne Pathogens.

Nanobodies have gained widespread application in immunoassays. However, their small size presents a significant challenge in achieving effective immobilization and optimal sensitivity. Here, we present a novel "one-for-two"-oriented immobilization platform based on an organism-bispecific nanobody (O-BsNb) scaffold, enabling highly sensitive detection of two bacterial pathogens. Through genetic engineering, a bispecific nanobody (BsNb) was engineered, targeting Salmonella spp. and Vibrio parahaemolyticus. The O-BsNb scaffold allowed one nanobody to bind specifically to inactivated bacteria, forming an organism-oriented immobilization platform, while the other served as the capture antibody. Consequently, the O-BsNb bioscaffold-based ELISA (O-ELISA) for individual detection of S. enteritidis and V. parahaemolyticus was established. When compared to the sandwich ELISA utilizing passive immobilization of monovalent nanobodies, the O-ELISA exhibited a remarkable 13.4- and 13.7-fold improvement in LOD for S. enteritidis and V. parahaemolyticus, respectively, highlighting the enhanced immobilization efficacy of the O-ELISA. Furthermore, the feasibility and reproducibility of the assay in practical samples were meticulously evaluated, revealing exemplary performance in terms of recovery precision and assay stability. These findings demonstrate the significant potential of the O-ELISA platform for the sensitive detection of macromolecules, opening new avenues for efficient pathogen identification in foodborne safety and clinical diagnostics.

Effects of nitrogen stress and nitrogen form ratios on the bacterial community and diversity in the root surface and rhizosphere of Cunninghamia lanceolata and Schima superba.

Background: The bacterial communities of the root surface and rhizosphere play a crucial role in the decomposition and transformation of soil nitrogen (N) and are also affected by soil N levels and distribution, especially the composition and diversity, which are sensitive to changes in the environment with high spatial and temporal heterogeneity of ammonium N (NH4 +-N) and nitrate N (NO3 --N). Methods: One-year-old seedlings of Cunninghamia lanceolata and Schima superba were subjected to N stress (0.5 mmol L-1) and normal N supply (2 mmol L-1), and five different N form ratios (NH4 +-N to NO3 --N ratio of 10:0, 0:10, 8:2, 2:8, and 5:5) were created. We analyze the changes in composition and diversity of bacteria in the root surface and rhizosphere of two tree species by high-throughput sequencing. Results: Differences in the composition of the major bacteria in the root surface and rhizosphere of C.lanceolata and S. superba under N stress and N form ratios were not significant. The dominant bacterial phyla shared by two tree species included Proteobacteria and Bacteroidota. Compared to normal N supply, the patterns of diversity in the root surface and rhizosphere of two tree species under N stress were distinct for each at five N form ratios. Under N stress, the bacterial diversity in the root surface was highest at NH4 +-N to NO3 --N ratio of 10:0 of C. lanceolata, whereas in the root surface, it was highest at the NH4 +-N to NO3 --N ratio of 0:10 of S. superba. The NH4 +-N to NO3 --N ratio of 5:5 reduced the bacterial diversity in the rhizosphere of two tree species, and the stability of the bacterial community in the rhizosphere was decreased in C. lanceolata. In addition, the bacterial diversity in the root surface was higher than in the rhizosphere under the N stress of two tree species. Conclusion: The bacterial compositions were relatively conserved, but abundance and diversity changed in the root surface and rhizosphere of C. lanceolata and S. superba under N stress and different N form ratios. The heterogeneity of ammonium and nitrate N addition should be considered for N-stressed environments to improve bacterial diversity in the rhizosphere of two tree species.