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A 28-day microcosm experiment was conducted using three paddy soils (an alluvial paddy soil, a loess-formed paddy soil, and a yellow clayey paddy soil) to investigate the impact of procyanidin on N2O emissions and associated microbial mechanisms. The efficacy of procyanidin on N2O emissions varied among the paddy soils tested, with an average inhibition rate ranging from 2.7% in the alluvial paddy soil to 57.1% in the loess-formed paddy soil. Furthermore, suppression of N2O emissions by procyanidin occurred alongside fluctuations in nitrate reductase activity and nirS- and nirK-type denitrifiers abundance. The correlation analysis indicates that nitrate reductase, clade I nirS-denitrifiers, clade I or II, and clade III nirK-denitrifiers were closely linked to N2O emissions. These findings provide evidence that procyanidin is capable of limiting N2O emissions in paddy soils by inhibiting nitrate reductase and different clades of nirS-/nirK-denitrifiers. [ABSTRACT FROM AUTHOR]

A microcosm study was established using three arable soils differing in both physicochemical properties and AOB or AOA dominance of ammonia oxidization. Nitrification and N2O emissions were quantified under 10 Pa C2H2, 1-octyne, or 3,4-dimethylpyrazole phosphate (DMPP), and the community composition and abundance of AOA and AOB were assessed. Amendment of soil with DMPP had a comparable effect to 1-octyne on AOB activities, composition, and N2O emissions across soils. By blocking AOB activity, both DMPP and 1-octyne supported higher rates of AOA growth in both the acid and alkaline soils. Approximately, 50% of ammonia-oxidizing activity in the acid soil was attributed to AOB activity by phylotypes affiliated with Nitrosomonas communis. When AOB were blocked by DMPP or 1-octyne across all soils, recovery of AOA communities was associated with the increased abundance of Nitrososphaera viennesis. [ABSTRACT FROM AUTHOR]

Background and aims: Silicon (Si) is known to alleviate aluminum (Al) toxicity in a number of plant species; however, the mechanisms of Si-triggered Al detoxification have not been elucidated, especially in rice (Oryza sativa). We investigated the interactions between Si and Al in root and the role of cell wall polysaccharides in rice resistance to Al. Methods: Rice seedlings were grown in 0.5 mM CaCl2 solution with or without 50 µM Al and 1.0 mM H4SiO4 for 24 h. The cell expansion and oxidative injury of root were measured by histochemical analyses; Al accumulation and distribution in root apices were determined by inductively coupled plasma mass spectrometry (ICP-MS); the degree of pectin methylesterification was analyzed by immunofluorescence, and the expression of genes (e.g. OsPME) related to Al resistance was measured by quantitative real-time PCR. Results: Si relieved the inhibition of cell elongation and oxidative injury caused by Al and significantly reduced Al content (by about 41 %) in cell wall (CW). Meanwhile, Si inhibited pectin methylesterase (PME) activity and its gene expression, thereby increasing the degree of pectin methylesterification, and reduced the content of hemicellulose, which was the main binding site for Al in CW, under Al stress. Furthermore, Si decreased the non-exchangeable Al fraction of CW in root, but did not change the cation exchange capacity of CW. Conclusions: Si reduces the deposition of Al in the cell wall of rice root apex by decreasing both the degree of pectin demethylesterification and the content of hemicellulose, thereby alleviating Al stress. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphene enables copper nanodroplets to form hexagonal close-packed layers. • The TCP atoms in copper nanodroplets hinders the formation of crystal atoms. • Graphene improves the temperature and life-time of the liquid–solid transition. • Graphene affects the nucleation work and crystallization pathway of nanodroplets. • Wettability can tune the temperature and lifetime of solid–liquid coexistence. The microstructure determines the macro properties, so the chemical and physical properties of nanoparticles can be tuned by changing their structures. A molecular dynamics simulation for the rapid solidification of Cu nanodroplets on the graphene sheet is conducted to investigate the effect of substrate on nanoparticles. The phase transition, structure evolution, and crystallinity are quantified by the potential energy, the largest standard cluster analysis, and Bond-orientation order parameters. It is found that the solidification is inhomogeneous and stepwise crystallization. Interestingly, originating from the graphene wettability, different solid–liquid coexistence states are obtained that may have the potential to modify the chemical and physical reactions on nanoparticles. The temperature of this solid–liquid coexistence state depends strongly on the structural evolution of crystallization and thus can be regulated by the wetting properties of the graphene substrate. These results significantly extend the fundamental understanding of heterogeneous nucleation in nanodroplets, providing important insights for designing and fabricating composite materials with multifunctional properties. [ABSTRACT FROM AUTHOR]

Silicon (Si) can alleviate salt stress by decreasing Na+ bypass flow in rice (Oryza sativa L.), however, the mechanisms underpinning remain veiled. In this study, we investigated the roles of OsLsi1 and OsLsi2 in Si-induced reduction of bypass flow and its resultant alleviation of salt stress by using lsi1 and lsi2 mutants (defective in OsLsi1 and OsLsi2, respectively) and their wild types (WTs). Under salt stress, Si promoted plant growth and decreased root-to-shoot Na+ translocation in WTs, but not in mutants. Simultaneously, quantitative estimation and fluorescent visualization of trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic (PTS, an apoplastic tracer) showed Si reduced bypass flow in WTs, but not in mutants. Energy-dispersive X-ray microanalysis (EDX) showed Si was deposited at root endodermis in WTs, but not in mutants. Moreover, results obtained from root split experiment using lsi1 WT showed down-regulated expression of Si transport genes (OsLsi1 and OsLsi2) in root accelerated Si deposition at root endodermis. In summary, our results reveal that Si deposition at root endodermis and its resultant reduction of Na+ bypass flow is modulated by OsLsi1 and OsLsi2 and regulated by the expression of OsLsi1 and OsLsi2 , implying that root Si deposition could be an active and physiologically-regulated process in rice. • Si deposition at root endodermis reduces Na+ bypass flow and alleviates salt stress. • Root Si deposition is modulated by OsLsi1 and OsLsi2. • Down-regulated OsLsi1 and OsLsi2 accelerated endodermis Si deposition. • Si deposition in root could be an active and physiologically-regulated process. [ABSTRACT FROM AUTHOR]

Aims: As a vital polysaccharide related to mechanisms of plant resistance to trace metal in the root cell wall, the role of hemicellulose in cadmium (Cd) accumulation in hyperaccumulators is still unknown. We investigated hemicellulose modification in response to Cd in two populations of Sedum alfredii. Methods: Nonhyperaccumulating population (NHP) and hyperaccumulating population (HP) of S. alfredii were grown in nutrient solutions with or without 25 μM Cd for 15 d. Monosaccharide composition of root cell wall hemicellulose and its remolding mechanisms (e.g. enzyme activity and gene expression) were analyzed by using gas chromatography-mass spectrometer (GC-MS), fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance (NMR) and quantitative real-time PCR techniques. Results: In 25 μM Cd treatment, root cell wall hemicellulose in the NHP significantly (P < 0.05) increased and its hemicellulose-bound Cd was nearly 2.5-fold higher than that of HP. In the presence of Cd, xylose and glucose, proved to be the main component of hemicellulose, were higher in the NHP than in the HP owing to the up-regulation of XET/XEH and encoding gene (XTH 31). 113Cd-NMR and FTIR results indicated that hemicellulose with hydroxyl and carboxyl groups of HP retained less Cd than that of NHP. Conclusion: Hemicellulose modification decreased the Cd-binding capacity of the root cell wall and increased the entry of Cd in the shoot of HP S. alfredii. [ABSTRACT FROM AUTHOR]

The use of high-energy ions or clusters to bombard graphene is emerging as a new method for the theoretical study of graphene properties. In this study, using molecular dynamics simulations and empirical potentials, the behaviors of graphene after bombardment by C60 under different initial velocities from 13.7 to 15.7 km/s were investigated. The simulations showed four types of defects: Stone–Wales defects, single vacancy defects, multiple vacancy defects, and out-of-plane carbon adatoms. The self-healing phenomenon of defective graphene was observed. In the low-speed region (< 14.5 km/s), the self-healing ability of graphene is enhanced at higher temperature. However, the effect of temperature is not obvious in the high-speed region, where velocity dominates. To repair vacancy defects in graphene, a physical method was proposed. The initial positions of lost atoms were traced, and then, the atoms were slowly dropped into the vacancy defects to effect repair. The simulations provide a fundamental understanding of bombardment between graphene and C60 and propose a new method for repairing vacancy defects in graphene. [ABSTRACT FROM AUTHOR]

The study of two-dimensional flexible materials in mechanic and optics has gained significant attention. By applying strain to modify the internal structure of materials, researchers can investigate the resulting mechanical and optical changes, offering exciting opportunities for further exploration in this field. The electronic structure, mechanical properties, and optical properties of the two-dimensional trigonal system Bi 2 Te 2 Se under biaxial strain regulation were investigated by using the first-principles plane pseudopotential plane wave method based on density generalized function theory. The analysis reveals that the energy bandwidth of Bi 2 Te 2 Se decreases with increasing strain until the band gap reaches 0 at 9% strain, causing the system to shift from a semiconductor to a conductor. The electronic density of states is primarily determined by the 6 p orbitals of Bi and 5 p orbitals of Te. With regards to its mechanical properties, Bi 2 Te 2 Se satisfies the mechanical stability criterion under different strains. As the strain increases from 0% to 6%, the material becomes increasingly brittle, with its interior transitioning from metallic to covalent bonds. However, the material toughness begins to improve from 6% to 9%, with the interior transitioning from covalent to metallic bonding. The performance improvement of Bi 2 Te 2 Se varies depending on the two electric field polarization vectors along [1 0 0] and [0 0 1] directions under strain. The material shows distinct application prospects in terms of absorption coefficient, reflectivity, refractive index, and lossiness under two directions. This paper provides a theoretical reference for the future mechanical and optical applications of Bi 2 Te 2 Se. [ABSTRACT FROM AUTHOR]

Trivalent chromium [Cr(III)] is a threat to the environment and crop production. Silicon (Si) has been shown to be effective in mitigating Cr(III) toxicity in rice. However, the mechanisms by which Si reduces Cr(III) uptake in rice are unclear. Herein, we hypothesized that the ability of Si to obstruct Cr(III) diffusion via apoplastic bypass is related to silicic acid polymerization, which may be affected by Cr(III) in rice roots. To test this hypothesis, we employed hydroponics experiments on rice (Oryza sativa L.) and utilized apoplastic bypass tracer techniques, as well as model simulations, to investigate 1) the effect of Si on Cr(III) toxicity and its obstruction capacity via apoplastic bypass, 2) the effect of Cr(III) on silicic acid polymerization, and 3) the relationship between the degree of silicic acid polymerization and its Cr(III) obstruction capacity. We found that Si reversed the damage caused by Cr(III) stress in rice. Si exerted an obstruction effect in the apoplast, significantly decreasing the share of Cr(III) uptake via the apoplastic bypass from 18% to 11%. Moreover, Cr(III) reduced silica particles' radii and increased Si concentration in roots. Modeling revealed that a 5-fold reduction in their radii decreased the diffusion of Cr(III) in apoplast by approximately 17%. We revealed that Cr(III) promoted silicic acid polymerization, resulting in the formation of a higher number of Si particles with a smaller radius in roots, which in turn increased the ability of Si to obstruct Cr(III) diffusion. This negative feedback regulatory mechanism is novel and crucially important for maintaining homeostasis in rice, unveiling the unique role of Si under Cr(III) ion stress and providing a theoretical basis for promoting the use of Si fertilizer in the field. [Display omitted] • Si in rice mitigates Cr(III) stress by obstructing Cr(III) uptake via apoplastic bypass. • Cr(III) reduces Si particle radius and increases root Si concentration. • A great number of smaller Si particles can improve their obstructing effect. • Si in rice alleviates Cr(III) stress via a negative feedback regulatory mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • A data-driven machine learning approach is proposed for predicting metallic glass forming ability. • A three-step feature selection method was devised to effectively filter out the best feature set. • Oversampling and non-linear transformation techniques are used to improve the imbalance distribution of the data set. • A design solution for enhanced metallic glass forming ability is proposed based on the SHAP method. Scientists have extensively studied metallic glasses (MGs) for their excellent properties and potential applications. However, the limited glass forming ability (GFA) of MGs poses a significant challenge in engineering fabrication, severely limiting their scope of application. Herein, we collected data from 167 peer-reviewed research articles and 2 commonly used datasets and constructed a comprehensive dataset containing 2085 data points. We employed gradient boosting algorithmic models, such as XGBoost, LGBoost, and AdaBoost, for selecting the best feature set and constructing the most effective model from among 118 feature parameters through techniques such as three-step feature selection method, ten-fold cross-validation, and grid search. As the uneven distribution of the original dataset significantly impacts the model's performance, we implemented five nonlinear transformation techniques and three oversampling techniques to improve the model. The results indicated that the nonlinear and oversampling techniques improved the model's performance by improving the distribution balance. Finally, we interpreted the constructed models through Shapley additive explanation, providing relevant rules concerning GFA. The techniques employed and the rules presented herein contribute to the statistical understanding of GFA and may facilitate the discovery of novel MGs. [ABSTRACT FROM AUTHOR]

Salicylic acid (SA), as an enigmatic signalling molecule in plants, has been intensively studied to elucidate its role in defence against biotic and abiotic stresses. This review focuses on recent research on the role of the SA signalling pathway in regulating cadmium (Cd) tolerance in plants under various SA exposure methods, including pre-soaking, hydroponic exposure, and spraying. Pretreatment with appropriate levels of SA showed a mitigating effect on Cd damage, whereas an excessive dose of exogenous SA aggravated the toxic effects of Cd. SA signalling mechanisms are mainly associated with modification of reactive oxygen species (ROS) levels in plant tissues. Then, ROS, as second messengers, regulate a series of physiological and genetic adaptive responses, including remodelling cell wall construction, balancing the uptake of Cd and other ions, refining the antioxidant defence system, and regulating photosynthesis, glutathione synthesis and senescence. These findings together elucidate the expanding role of SA in phytotoxicology. [ABSTRACT FROM AUTHOR]

Anammox are unusual members of the microbial community contributing to N losses via anaerobic ammonium oxidation. Anammox use nitrite as a substrate and produce hydrazine as an intermediate product. Up to date, the effects of dissolved oxygen and moisture dynamics on anammox potential and microbial community in agricultural soils were poorly understood. In this study, we investigated the interaction of dissolved oxygen and moisture contents as factors affecting the soil anammox process. The experiment had four fertilization treatments i.e. Control (CK), Chemical fertilizer (CF), Pig composted manure plus chemical fertilizer (PMCF), and Straw returned to soil plus chemical fertilizer (SRCF) with different water contents, 70%-FC, Alternate wetting and drying (AWD), Flooding I (D.O 5.8 mg L−1), and Flooding II (D.O 2.6 mg L−1). 15N-isotopic tracer technique was used to evaluate the anammox and denitrification rates. The results showed that the anammox rate ranged from the lowest 0.56 nmol N 2 ·g−1·h−1 in CF (with 70% FC water) to the highest rate of 1.47 nmol N 2 ·g−1·h−1 in SRCF (with flooding II). In water treatments, the average lowest and highest anammox rates were in the 70% FC (0.61 nmol N 2 ·g−1·h−1) and Flooding II (1.14 nmol N 2 ·g−1·h−1), respectively. Moreover, under soil treatments, the minimum average anammox rate was found in the PMCF (0.76 nmol N 2 ·g−1·h−1) and maximum in the SRCF (1.01 nmol N 2 ·g−1·h−1). Interestingly, anammox genes copy numbers were highest in alternate wetting and drying conditions under all fertilizer treatments rather than in continuous flooding. The phylogenetic analysis showed that Ca. Brocadia was dominating while some of Ca. Jettenia was also present. In conclusion, alternate wetting and drying could increase the number of anammox bacteria and microbial diversity. Unlabelled Image • Alternate wetting and drying (AWD) can enhance Anammox rate and microbial diversity. • Consistently higher dissolved oxygen can inhibit the Anammox process/activity. • Long-term application of pig manure can decrease the Anammox activity. • Anammox activity has a positive relationship with hydrazine gene abundance. [ABSTRACT FROM AUTHOR]

Abstract Phytoextraction is an attractive strategy for remediation of soils contaminated by heavy metal (HM), yet the effects of this practice on biochemical processes involved in soil nutrient cycling remain unknown. Here we investigated the impact of successive phytoextraction with a Cd/Zn co-hyperaccumulator Sedum alfredii (Crassulaceae) on potential nitrification rates (PNRs), abundance and composition of nitrifying communities and functional genes associated with nitrification using archaeal and bacterial 16S rRNA gene profiling and quantitative real-time PCR. The PNRs in rhizosphere were significantly (P < 0.05) lower than in the unplanted soils, and decreased markedly with planting time. The decrease of PNR was more paralleled by changes in numbers of copy and transcript of archaeal amoA gene than the bacterial counterpart. Phylogenetic analysis revealed that phytoextraction induced shifts in community structure of soil group 1.1b lineage-dominated ammonia-oxidizing archaea (AOA), Nitrosospira cluster 3-like ammonia-oxidizing bacteria (AOB) and Nitrospira -like nitrite-oxidizing bacteria (NOB). A strong positive correlation was observed between amoA gene transcript numbers and PNRs, whereas root exudates showed negative effect on PNR. This effect was further corroborated by incubation test with the concentrated root exudates of S. alfredii. Partial least squares path model demonstrated that PNR was predominantly controlled by number of AOA amoA gene transcripts which were strongly influenced by root exudation and HM level in soil. Our result reveals that successive phytoextraction of agricultural soil contaminated by HMs using S. alfredii could inhibit ammonia oxidation and thereby reduce nitrogen loss. Graphical abstract Unlabelled Image Highlights • Successive phytoextraction by S. alfredii significantly reduced the PNR in rhizosphere. • Successive phytoextraction decreased the abundance and activity of archaeal amoA gene. • Successive planting with S. alfredii obviously altered the structure of nitrifying community. • Root exudates of S. alfredii inhibited ammonia oxidation by decreasing ammonia-oxidizing microbe activity. [ABSTRACT FROM AUTHOR]

Abscisic acid (ABA) is a key phytohormone underlying plant resistance to toxic metals. However, regulatory effects of ABA on apoplastic transport in roots and consequences for uptake of metal ions are poorly understood. Here, we demonstrate how ABA regulates development of apoplastic barriers in roots of two ecotypes of Sedum alfredii and assess effects on cadmium (Cd) uptake. Under Cd treatment, increased endogenous ABA level was detected in roots of nonhyperaccumulating ecotype (NHE) due to up‐regulated expressions of ABA biosynthesis genes (SaABA2, SaNCED), but no change was observed in hyperaccumulating ecotype (HE). Simultaneously, endodermal Casparian strips (CSs) and suberin lamellae (SL) were deposited closer to root tips of NHE compared with HE. Interestingly, the vessel‐to‐CSs overlap was identified as an ABA‐driven anatomical trait. Results of correlation analyses and exogenous applications of ABA/Abamine indicate that ABA regulates development of both types of apoplastic barriers through promoting activities of phenylalanine ammonialyase, peroxidase, and expressions of suberin‐related genes (SaCYP86A1, SaGPAT5, and SaKCS20). Using scanning ion‐selected electrode technique and PTS tracer confirmed that ABA‐promoted deposition of CSs and SL significantly reduced Cd entrance into root stele. Therefore, maintenance of low ABA levels in HE minimized deposition of apoplastic barriers and allowed maximization of Cd uptake via apoplastic pathway. Abscisic acid regulated the development of endodermal Casparian strips (CSs) and suberin lamellae (SL) in roots of S. alfredii exposed to Cd. Maintenance of low ABA levels in hyperaccumulating ecotype minimized deposition of CSs/SL and allowed maximization of Cd uptake via apoplastic pathway. [ABSTRACT FROM AUTHOR]

Abstract The nitrification inhibitor, 3,4-dimethylpyrazole phosphate (DMPP), can be used to reduce N 2 O emissions from agricultural ecosystems. However, the effectiveness of DMPP varies among soils, and this is due to both abiotic (e.g. soil properties) and biotic factors (e.g. ammonia oxidizers and denitrifier communities). Understanding the nature of these effects is necessary to improve the efficacy of DMPP, therefore encouraging wider adoption and environmental benefits. In particular, soil microbial properties associated with variation in efficacy remain largely unknown. In this study four contrasting arable soils (a grey desert soil, an alluvial paddy soil, a loess-formed paddy soil, and a red soil), were characterized based on DMPP inhibition of N 2 O emissions and associated microbial functional guilds. DMPP significantly inhibited nitrification and N 2 O emissions, with an average inhibitory rate ranging from 41.7% in a red soil to 90.0% in a grey desert soil. Ammonia oxidizing bacteria (AOB) and archaea (AOA) exhibited contrasting response patterns to DMPP addition. Notably, suppression of N 2 O emissions by DMPP only occurred alongside fluctuations in AOB abundance. However, when AOB were inhibited, AOA abundance increased. Soil-dependent response patterns to DMPP were observed for ammonia oxidizers and denitrifiers in terms of community structure. Partial least squares path modeling (PLS-PM) found that abiotic factors, particularly pH, and biological factors such as ammonia oxidizer communities, were closely linked to N 2 O emissions. Our findings provide evidence that: (i) DMPP effectively inhibits nitrification through inhibiting the abundance of AOB across soil types; (ii) releasing AOA from the competition with AOB allows AOA to efficiently grow and multiply, even under high ammonium conditions; and (iii) abiotic factors play a more important role than biotic factors in soil N 2 O emissions. Graphical abstract Image 1 Highlights • Reduction of N 2 O emissions by DMPP was attributed to AOB growth inhibition. • Inhibition of AOB grown by DMPP resulted in increased AOA abundance. • Release of AOA from competition with AOB allowed AOA growth in high N conditions. • Soil properties played a more important role in N 2 O emissions than microbial factors. [ABSTRACT FROM AUTHOR]

The urease inhibitor, N -( n -butyl) thiophosphoric triamide (NBPT), has been proposed to reduce synthetic fertilizer-N losses, including nitrous oxide (N 2 O) emissions from agricultural soils. However, the response of N 2 O emission to NBPT amendment is inconsistent across soils and associated microbial mechanisms remain largely unknown. Here we performed a meta-analysis of the effects of NBPT on N 2 O emissions and found NBPT significantly reduced N 2 O emissions in alkaline soils whereas no obvious effects exhibited in acid soils. Based on the finding of meta-analysis that pH was a key modifier in regulating the effect of NBPT on N 2 O emissions, we selected two arable soils differing in pH and conducted a microcosm study. In conjunction with measurement of N 2 O emission, community structure and abundance of functional guilds were assessed using T-RFLP and qPCR. Our results showed NBPT retarded urea hydrolysis and inhibited nitrification, but stimulated N 2 O emission in alkaline soil, whereas it exhibited no remarkable effects in acid soil, thereby only partly confirming the results of meta-analysis. Abundances of AOB and ureC -containing bacteria decreased, while abundance of AOA increased in both soils with NBPT addition. For acid soil, N 2 O emissions were significantly correlated with both abundances and community structures of AOA and ureC -containing bacteria, as well as abundance of AOB; for alkaline soil, abundances and community structures of AOB were correlated with N 2 O emission, as well as community structures of ureC -containing bacteria and archaea, indicating an inconsistent response pattern of community traits of N 2 O emissions-related functional guilds to NBPT between alkaline soil and acid soil. Our findings suggest that (i) efficacy of NBPT in N 2 O emission was mainly influenced by soil pH and (ii) variable effects of NBPT on N 2 O emission might originate not only from the direct effect of NBPT on community traits of urease-positive microbes, but from the indirect effect on ammonia oxidizers. [ABSTRACT FROM AUTHOR]

Quadruple Ti particles microstructure evolution by sintering. [Display omitted] • The sintering process of quadruple Ti particles is studied utilizing the MD method. • The initial arrangement of the particles affects the microstructure of the quadruple Ti particles. • The higher the sintering temperature, the easier the transformation of HCP-Ti into BCC-Ti. • A new calculation method of multiparticles fusion ratio is proposed. The sintering dynamics of binary particles have been extensively studied; however, the sintering behavior of multiparticles still needs further investigation because it plays a key role in many industrial processes and advanced technologies. Herein, we used molecular dynamics simulations to investigate the sintering dynamics of quadruple titanium (Ti) particles. We investigated two particle arrangement configurations of Ti particles, ααββ and αβαβ, at three sintering temperatures (900 K, 1300 K, and 2000 K) to explore the microstructural changes of Ti particles during sintering. Furthermore, we proposed a formula for calculating the fusion ratio of multiple particles. The results show that ααββ-Ti could retain its HCP structure when sintered at 1300 K and 900 K, whereas only BCC-Ti was observed after sintering at high temperatures. The effect of diffusion mechanisms was more substantial at high temperatures, and the higher the sintering temperature, the better the particle fusion effect. In addition to the effect of temperature on atomic migration, different particle arrangement configurations can impact atomic migration. [ABSTRACT FROM AUTHOR]

The presence of Schottky barriers at the metal-semiconductor interfaces has always been troubling people all over the world. Therefore, achieving Ohmic contacts for high-performance and energy-efficient Schottky devices becomes imminent. Bulk metals as electrodes usually produce a severe Fermi level pinning (FLP) effect due to the presence of dangling bonds on their surfaces. Here, our recent work shows that the FLP effect can be effectively suppressed in MoSi 2 N 4 (MSN) and WSi 2 N 4 (WSN) contact with seven two-dimensional (2D) metals. The measured n-type and p-type pinning factors S are 0.42, −0.63 for MSN, 0.43, −0.51 for WSN, respectively, indicating a weak FLP effect. We also confirm that Ohmic contacts can be achieved just by Van der Waals stacking. Ohmic contacts can be obtained for NbS 2 , TaS 2 , TaSe 2 , and VS 2 in contact with MSN and for NbS 2 , NbSe 2 , TaS 2 , and VS 2 in contact with WSN. Our work unveils that MSN/2D metals and WSN/2D metals contacts show great potential in high-performance Schottky electronic devices. • Our work shows that efficient Ohmic contacts can be achieved simply by van der Waals stacking without applying strain or external electric fields. • Our work demonstrates the measured pinning factors S are higher than other common two-dimensional materials. MoSi 2 N 4 and WSi 2 N 4 show a weak Fermi level pinning effect and promising application. • Our work provides a new technique for highly efficient ohmic contact in MoSi 2 N 4 /2D and WSi 2 N 4 /2D metals contacts. [ABSTRACT FROM AUTHOR]

In this study, soil samples from the typical rice-wheat cropping system in Jiangsu Province, China, subjected to different fertilizer application treatments-no carbon (CK), urea (UR), straw (SR), pig manure (PM), starch (ST), and glucose (GL)-were used to determine potential anaerobic ammonium oxidation (anammox) rate and its association with bacterial abundance, diversity, and activity by using DNA stable isotope probing combined with N isotope tracing and molecular techniques. The effects of different organic carbon sources on anammox were significant, in the following order: GL > ST, SR > UR > PM; anammox activity differed significantly across treatments; however, the C active anammox bacteria were only closely related to Ca. Brocadia. The anammox hydrazine synthase β subunit functional gene sequences were highly associated with the Candidatus genus Brocadia in PM and CK treatments. The different organic carbon sources had different inhibitory effects with anammox rate, which dropped from 3.19 to 1.04 nmol dinitrogen gas g dry soil h among treatments. About 4.2-22.3% of dinitrogen gas emissions were attributed to anammox and indicated that a specific population of anammox bacteria was present and varied with the addition of exogenous organic compounds in paddy soils, although a small part of dinitrogen gas was emitted from the soil via anammox. [ABSTRACT FROM AUTHOR]

The growth of GaN crystals at different pressures was studied by molecular dynamics simulation employing the Stillinger–Weber potential, and their structural properties and defects were characterized using the radial distribution function, the Voronoi polyhedron index method, and a suitable visualization technology. Crystal structures formed at 0, 1, 5, 10, and 20 GPa featured an overwhelming number of <4 0 0 0> Voronoi polyhedra, whereas amorphous structures comprising numerous disordered polyhedra were produced at 50 GPa. During quenching, coherent twin boundaries were easily formed between zinc-blende and wurtzite crystal structures in GaN. Notably, point defects usually appeared at low pressure, whereas dislocations were observed at high pressure, since the simultaneous growth of two crystal grains with different crystal orientations and their boundary expansion was hindered in the latter case, resulting in the formation of a dislocation between these grains. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) is an important process in many marine and paddy ecosystems. However, few studies have reported on the contribution to the nitrogen cycle of anammox and its dynamics in rice–wheat cropping systems with different fertilization regimes. Here, isotope tracing and molecular techniques were used to determine the potential rates of anammox and their association with bacterial abundance, diversity, and activity. Rice–wheat cropping systems at two sites in Jiangsu Province, China were selected and the treatments at each site were: 1) no fertilization (CK), 2) 100% chemical fertilization (CF), 3) pig manure compost plus 50% chemical fertilization (PMCF), and 4) straw plus 100% chemical fertilization (SRCF). The results revealed that anammox bacteria with high abundance were detected in both the wheat and rice seasons. The abundance of anammox in PMCF treatment was higher than that in SRCF treatment in both Changshu and Jintan. Moreover, the abundance of anammox bacteria in CF treatment was significantly higher than that in CK in Changshu. Analysis of anammox hydrazine synthase β subunit ( hzs-β ) gene sequences showed that in the rice season, the anammox bacteria Ca. Brocadia, Ca. Scalindua, and Ca. Jettenia were present. In contrast, all of the anammox hydrazine oxidase ( hzo ) genes were affiliated with Ca. Brocadia, suggesting that hzs genes are more representative of anammox biological diversity compared to hzo . Sequences from the PMCF treatment where affiliated with both Ca. Jettenia and Ca. Brocadia, and showed the highest diversity. Anammox activity was detected in both the wheat and rice seasons, but there were significant differences between seasons. The anammox rates were in the range 0.34 to 1.04 nmol dinitrogen gas ∙ g − 1 dry soil ∙ h − 1 , and 3.15 to 9.62% of dinitrogen gas emissions were attributed to anammox. However, no significant difference among the fertilizer treatments for anammox activity was found in the study. [ABSTRACT FROM AUTHOR]

Interactions between roots and microbes affect plant's resistance to abiotic stress. However, the structural and functional variation of root-associated microbiomes and their effects on metal accumulation in hyperaccumulators remain poorly understood. Here, we characterize the root-associated microbiota of a hyperaccumulating (HP) and a non-hyperaccumulating (NHP) genotype of Sedum alfredii by 16S ribosomal RNA gene profiling. We show that distinct microbiomes are observed in four spatially separable compartments: the bulk soil, rhizosphere, rhizoplane, and endosphere. Both the rhizosphere and rhizoplane were preferentially colonized by Proteobacteria, and the endosphere by Actinobacteria. The rhizosphere and endophytic microbiomes were dominated by the family of Sphingomonadaceae and Streptomycetaceae, respectively, which benefited for their survival and adaptation. The bacterial α-diversity decreases along the spatial gradient from the rhizosphere to the endosphere. Soil type and compartment were strongest determinants of root-associated community variation, and host genotype explained a small, but significant amount of variation. The enrichment of Bacteroidetes and depletion of Firmicutes and Planctomycetes in the HP endosphere compared with that of the NHP genotype may affect metal hyperaccumulation. Program PICRUSt predicted moderate functional differences in bacterial consortia across rhizocompartments and soil types. The functional categories involved in membrane transporters (specifically ATP-binding cassette transporters) and energy metabolism were overrepresented in endosphere of HP in comparison with NHP genotypes. Taken together, our study reveals substantial variation in structure and function of microbiomes colonizing different compartments, with the endophytic microbiota potentially playing an important role in heavy metal hyperaccumulation. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of silicate fertilizer on denitrification and associated gene abundance in a paddy soil. A consecutive trial from 2013 to 2015 was conducted including the following treatments: control (CK), mineral fertilizer (NPK), NPK plus sodium metasilicate (NPK + MSF), and NPK plus slag-based silicate fertilizer (NPK + SSF). Real-time quantitative PCR (qPCR) was used to analyze the abundances of nirS, nirK, and nosZ genes. Potential NO emissions and ammonium and nitrate concentrations were related to the nirS and nirK gene abundance. Compared with the NPK treatments, the addition of a Si fertilizer decreased NO emission rates and denitrification potential by 32.4-66.6 and 22.0-59.2%, respectively, which were probably related to increased rice productivity, soil Fe availability, and soil N depletion. The abundances of nirS and nirK genes were decreased by 17.7-35.8% and 21.1-43.5% with addition of silicate fertilizers, respectively. Rates of total NO and NO from denitrification (DeNO) emission were positively correlated with the nirS and nirK gene abundance. Nitrate, exchangeable NH , and Fe concentrations were the main factors regulating the nirS and nirK gene abundance. Silicate fertilization during rice growth may serve as an effective approach to decreasing NO emissions. [ABSTRACT FROM AUTHOR]

Long-term intensive fertilization is a practice common around the world and gradually alters soil microbiome, however, its influences on the temporal resilience of soil multifunctionality to biodiversity loss and biodiversity-multifunctionality relationships remain poorly understood. Here, we manipulated soil biodiversity using the dilution-to-extinction approach to examine the temporal variability in individual functions, soil multifunctionality and their relationships with bacterial and fungal communities under different fertilization treatments during a 90-day re-colonization process. We found that organic fertilization accelerated the resilience of single functions and soil multifunctionality to biodiversity loss compared with mineral fertilization and unfertilized control. The fungal community was less resilient than bacterial community to disturbances caused by fertilization and dilution. Bacterial but not fungal diversity was significantly and positively related to multifunctionality, and the strength of the diversity-multifunctionality relationships in organic fertilized soil was 3- and 67-fold higher than that in unfertilized and mineral fertilized soil, respectively. Both organic and mineral nutrient inputs promoted copiotroph-dominated bacterial assemblages (including Proteobacteria and Bacteroidetes members) and suppressed oligotrophs (mostly Acidobacteria and Chloroflexi), which paralleled multifunctionality resilience patterns in fertilized soils. β-Diversity of bacterial copiotrophs alone or in combination was significantly related to changes in multifunctionality. Random forest analysis and structural equation modeling indicated that bacterial community diversity and composition along with soil carbon and nitrogen basically determined soil multifunctionality, with 70% of the variance in multifunctionality being explained. Rare taxa from the bacterial copiotrophs were particularly important for maintaining multifunctionality. Our results underline the importance of fertilization-induced shifts in microbial ecophysiological strategies for promoting the resilience of soil multifunctionality to biodiversity loss, and the need to preserve the diversity of rare copiotrophic taxa for stable provision of ecosystem functions under future environmental change. • Organic fertiliser promoted soil multifunctionality resilience to biodiversity loss. • Bacterial communities were more important than fungi for predicting multifunctionality. • Multifunctionality resilience reflected fertilization-induced ecophysiological shifts. • Rare copiotrophic bacteria played an over-proportional role in multifunctionality. [ABSTRACT FROM AUTHOR]

The association between microbial communities and plant growth in long-term fertilization system has not been fully studied. In the present study, impacts of long-term fertilization have been determined on the size and activity of soil microbial communities and wheat performance in a red soil (Ultisol) collected from Qiyang Experimental Station, China. For this, different microbial communities originating from long-term fertilized pig manure (M), mineral fertilizer (NPK), pig manure plus mineral fertilizer (MNPK), and no fertilizer (CK) were used as inocula for the Ultisol tested. Changes in total bacterial and fungal community composition and structures using Ion Torrent sequencing were determined. The results show that the biomass of wheat was significantly higher in both sterilized soil inoculated with NPK (SNPK) and sterilized soil inoculated with MNPK (SMNPK) treatments than in other treatments ( P < 0.05). The activities of β-1,4- N-acetylglucosaminidase (NAG) and cellobiohydrolase (CBH) were significantly correlated with wheat biomass. Among the microbial communities, the largest Ascomycota phylum in soils was negatively correlated with β-1,4-glucosidase (βG) ( P < 0.05). The phylum Basidiomycota was negatively correlated with plant biomass (PB) and tillers per plant (TI) ( P < 0.05). Nonmetric multidimensional scaling analysis shows that fungal community was strongly correlated with long-term fertilization strategy, while the bacterial community was strongly correlated with β-1,4- N-acetylglucosaminidase activity. According to the Mantel test, the growth of wheat was affected by fungal community. Taken together, microbial composition and diversity in soils could be a good player in predicting soil fertility and consequently plant growth. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two nitrogen-cycle processes that have recently received more attention. However, few studies have been performed on the effects of different fertilizations in upland-cropping soil. Therefore, the objective of this work was to assess the effects of different fertilizations on the distribution and diversity of anammox and n-damo bacteria along the profiles of soil during wheat cropping season of the paddy-upland rotation system. In our study, a five-year fertilization (from 2010 to 2015) was conducted on a paddy-upland rotation field, with four fertilizer treatments: an unfertilized control (CK), chemical fertilizer (CF), pig manure plus 50% chemical fertilizer (PMCF), and rice straw plus 100% chemical fertilizer (SRCF). The quantitative PCR results showed that the total abundance of anammox and n-damo bacteria during the wheat cropping season were lower than those reported previously in paddy soils, and the abundance of anammox bacteria decreased with soil depth, but the abundance of n-damo bacteria remarkably increased. Long-term fertilization reduced the abundance of anammox bacteria in the 0–40 cm layer and that of n-damo bacteria in the 20–60 cm layer. Furthermore, Illumina high-throughput sequencing of the hzs B and pmo A genes was performed, showing that anammox bacteria were affiliated with “ Candidatus Brocadia” and n-damo bacteria were related to “ Candidatus Methylomirabilis oxyfera.” Diversity analysis demonstrated that the diversity of anammox bacteria increased with soil depth. Among the fertilizer treatments evaluated, pig manure plus 50% chemical fertilizer (PMCF) yielded the highest abundance and lowest diversity of anammox bacteria in the 20–60 cm layer. Moreover, fertilization diversified the community structure of anammox bacteria in deep soil. For n-damo bacteria, a higher diversity was found under chemical fertilization than under other treatments. Redundancy analysis showed that the community structure of anammox was mainly related to of total nitrogen and soil organic carbon and that of n-damo bacteria was mainly associated with NO 3 − content. Overall, soil depth and fertilization patterns influenced the distribution and diversity of anammox and n-damo bacteria by changing the soil properties. [ABSTRACT FROM AUTHOR]

Temperature is an important factor governing the community traits of N 2 O-emission related functional guilds (mainly autotrophic ammonia oxidizers and heterotrophic denitrifiers) and their activities. However, there have been few attempts to explore the broad response patterns of these guilds to temperature changes across arable soils. For this, a temperature-controlled (15, 25 and 35 °C) microcosm experiment was conducted using three arable soils (Fujian, Gansu, and Jiangsu) in China under two different fertilizations (no fertilization control (CK) and inorganic fertilization (NPK)). In conjunction with the measurement of N 2 O emission, the community structure and abundance of ammonia oxidizing archaea (AOA) and bacteria (AOB), as well as nirS - and nirK -denitrifiers were assessed using T-RFLP and quantitative PCR, respectively. The analysis of community traits indicated a consistent response pattern of AOAs to temperature in terms of guild abundance, and a consistent effect of inorganic fertilization on the abundance of AOBs, but soil-dependent response patterns to fertilization and temperature were found for nirS - and nirK -denitrifiers in terms of abundance and community structure. The correlation analysis suggested that AOAs possibly assumed a role in N 2 O emission in all the tested soils, and nirS -denitrifiers probably participated in N 2 O emission in both the Fujian and Gansu soil, while a considerable amount of N 2 O emission in the Jiangsu soil might have been derived from heterotrophic nitrification. [ABSTRACT FROM AUTHOR]

• The void defects significantly affect the deformation and plasticity in FeNiCrCoCu HEAs. • The deformation behavior reveals that the void is the main cause of initial strain. • The effects of different temperatures and strain rates on FeNiCrCoCu HEAs voids were explored. • The tensile strength significantly increases at a strain rate of 1010 s−1 compared to 109 and 108 s−1. While preparing and using high entropy alloys (HEAs), many defects such as voids are inevitably formed. The effects of voids on the mechanical properties of FeNiCrCoCu HEAs are investigated using molecular dynamics simulations. The evolution of voids is examined by using models with one or two voids considering different void sizes, applied strain rates, and temperatures. The results demonstrate that the existence of the voids does influence the mechanical properties of HEAs. The tensile strength of the single-void model is higher than that of double-void model. The stress–strain curves demonstrate that a larger initial void size could reduce the tensile strength. During the tensile deformation, all dislocation emission occurs initially from the surface of the void. However, it occurs between the two voids in double-void models, which causes the deformation of the voids. With temperature increases, the tensile strength decreases. Under various strain rates, the tensile strength slightly rises at strain rates ranging from 108to 109 s−1. However, it significantly increases at a strain rate of 109 to 1010 s−1. [Display omitted] The development of void defect in FeNiCrCoCu HEAs under the tensile process at 300 K and a strain rate of 109 s−1. (a) single-void model; (b) double-void model. [ABSTRACT FROM AUTHOR]

The increasing input of nitrogen (N) fertilizers has a considerable impact on agricultural soil carbon (C) cycling due to its influence on soil microbial abundance and assemblages. However, the microbial mechanism underlying the response of straw-induced priming effect to long-term N application remains an open question. Here, using soils with three N fertilization levels (0, 300, and 570 kg N ha−1 y−1) from a long-term experimental site, we established a 40-day microcosm experiment to investigate the priming effect of straw addition on SOM mineralization and the associated microbial activity and community composition. We found that long-term N application significantly inhibited soil respiration while increasing straw-induced priming effect. The soil microbial biomass (including bacterial and fungal abundance) decreased with increasing N levels, accompanied by decreased bacterial α -diversity and altered β -diversity. In addition, the N fertilization level significantly influenced bacterial and fungal indicator species that were sensitive to straw addition (si OTUs) and long-term N fertilization (ni OTUs), as well as their co-occurrence patterns. In the first three days of straw decomposition, long-term N fertilization decreased the oligotroph-to-copiotroph ratio of bacterial si OTUs. In contrast, long-term N fertilization increased this ratio on days 20 and 40, along with facilitated microbial investment in extracellular enzymes and microbial N demand. This caused a stronger "N mining" process and consequently enhanced the priming effect in soil exposed to long-term N fertilization at the later stage of incubation. Linking indicator species analysis with priming effect, these results advance our understanding of the complex C cycling in agricultural soils undergoing long-term nitrogen management. • N fertilization increased the relative abundance of specific copiotrophic bacteria. • The composition of indicator OTUs was determined by N fertilization level. • N fertilization level altered the co-occurrence patterns of indicator OTUs. • Response of straw-indicator OTUs to N fertilization echoed the change of priming effect. [ABSTRACT FROM AUTHOR]

Recently, SiC has gained considerable interest owing to its avant-garde nature and relevance in future applications. Molecular dynamics simulation was performed to investigate nanopolishing of three-body diamond abrasives on workpieces that had undergone cluster deposition and annealing processes. The coordination number, temperature, atomic distribution, kinetic energy, friction coefficient, crystallization, and average height of the workpiece were determined. Further, the effects of different polishing depths and polishing speeds on the physical properties of the workpiece were determined. Results show that polishing depth considerably affects the coordination number, surface morphology, friction coefficient, crystallization, and temperature of the workpiece. The surface of the workpiece was polished while maintaining the crystallization rate at a polishing depth of 20 Å. With an increase in the polishing rate, the coefficient of friction decreased, the temperature of the workpiece increased, and the polishing trajectory became clearer, with a better crystallization at 1 Å/ps. [Display omitted] • The workpiece undergoes the process of deposition and annealed. • Three three-body diamond abrasives are parallel to each other, more like a "brush". • Friction coefficient of the abrasive is related to the temperature of the workpiece. • The height of SDL region is closely related to polishing depth and speed. [ABSTRACT FROM AUTHOR]

The electronic structure and optical properties of Mo 2 C with different surface atomic layer thicknesses (SALTs) have been investigated by employing the plane wave ultra-soft pseudopotential method based on the first principles. It is found that the LDA density generalization approximation is most suitable for the optimization of the geometry of Mo 2 C, under which the lowest energy and most stable structure are obtained. As the SALT decreases, the hybridization of Mo-d and Mo-p electrons in the valence band forms strongly hybridized orbitals. It suppresses the photoelectron leap of and increases the band gap, allowing the conversion of Mo 2 C from metal to semiconductor. Therefore, the dielectric function, refractive index, reflection spectrum, and absorption spectrum can be improved by adjusting the SALT of Mo 2 C. These findings can provide a theoretical basis for improving and optimizing its photoelectronic properties. • The LDA density generalization approximation is most suitable for the optimization of the geometry of Mo 2 C. • The transformation of Mo 2 C from metallic to semiconductor properties was achieved by adjusting SALT. • Different SALT can effectively modulate the optical properties of Mo 2 C, increase the optical utilization. [ABSTRACT FROM AUTHOR]

• Detailed comparison and depiction of different wind field models are listed. • Four international standards for wind load in transmission system are compared. • Wind-induced electrical component failure model in transmission system is summarized. • Data-driven outage prediction model in distribution system is summarized. • Machine learning algorithms combination and zero-inflation handling are reviewed. Given that wind hazards pose a considerable damage to power system in various countries, researchers have developed methods for disaster prevention to diminish the vulnerabilities. This paper attempts to review the failure analysis procedure under the impact of wind hazards, considering the following attributes: wind field generation method, wind-induced electrical component failure model in transmission system, and building outage prediction model from data-driven view in distribution system. First, we compare the calculation of circulation and translation wind speed, with geographical, temporal and uncertainty factors of wind speed considered. Then, we introduce the wind-induced component failure models derived by wind load calculation and fragility curves. The application of the series reliability model in multiple cluster failures is briefly described. Finally, we summarize the applications of data analysis in building outage prediction models. The reviewed literature contains the statistical learning methods and machine learning methods. It is concluded that the frameworks for component-level failure model and user-level outage prediction model are well established. However, most of the studies still develop two models, separately. Future researchers may target at the hybrid application of both models to better provide fault analysis, prediction and emergency in power system under wind hazards. [ABSTRACT FROM AUTHOR]

Nitrogen addition to croplands greatly increases global emissions of the potent greenhouse gas nitrous oxide (N 2 O). Three ammonia-oxidizing functional guilds constitute the major producers of N 2 O in agricultural soils, but their relative contributions are still poorly understood, especially the newly discovered and widespread complete ammonia oxidizers (comammox). To fill this knowledge gap, we used three nitrification inhibitors: acetylene, 1-octyne, and 3,4-dimethylpyrazole phosphate (DMPP), to selectively suppress the activity of different ammonia oxidizer guilds to discriminate their relative contributions to N 2 O production in an alkaline arable soil. The results indicated that DMPP completely inhibited the growth of comammox Nitrospira clade A and ammonia-oxidizing bacteria (AOB) but promoted ammonia-oxidizing archaea (AOA) growth, while the abundance of comammox Nitrospira clade A increased in the presence of 1-octyne at high ammonium (NH 4 +) concentrations. AOB dominated N 2 O production in soils with inorganic NH 4 + amendment, followed by AOA, while comammox Nitrospira contributed to less than 3% of total N 2 O emissions with an N 2 O yield of ∼0.083% (N 2 O per molecule of nitrate). The abundance of comammox Nitrospira clade A was approximately two orders of magnitude lower than that of canonical ammonia-oxidizers. Phylogenetic analysis revealed that the majority of comammox Nitrospira clade A belonged to a new cluster that was separated from the known comammox bacterium. Taken together, our results clearly and strongly demonstrate that comammox Nitrospira play only a minor role in N 2 O emissions in a heavily fertilized alkaline arable soil. • Comammox Nitrospira only contributed to less than 3% of total N 2 O emissions from a heavily fertilized arable soil. • DMPP inhibited the growth of AOB and comammox Nitrospira clade A, but 1-octyne only inhibited the growth of AOB. • The growth of AOA was further increased when both AOB and comammox Nitrospira clade A were inhibited. [ABSTRACT FROM AUTHOR]

Root cell wall (RCW) remodeling induced by copper oxide nanoparticles (CuO NPs) and its consequences for root growth of lettuce (Lactuca sativa L.) were investigated in this study. The results showed that a low concentration of CuO NPs (5 mg L−1) stimulated reactive oxygen species (ROS) signaling, led to the degradation of pectin by H 2 O 2, and promoted root elongation by 22.1% by triggering RCW loosening. However, under treatment with a high concentration of CuO NPs (450 mg L−1), the unordered distribution of pectin homogalacturonan enhanced cell wall adhesion. Also, the increased xyloglucan and the decreased xyloglucan endotransglycosylase/hydrolase (XTH) activities caused cell wall stiffening, making it difficult for lettuce roots to extend. Meanwhile, the contents of hemicellulose and low-methylated pectin were increased remarkably due to the downregulation of the encoding genes XTH15 , XTH17 , XTH31 and the upregulation of PME3 , which provided abundant binding sites of RCW with CuO NPs. In addition, the accelerated development of the apoplastic barrier and root lignification blocked the absorption of CuO NPs, and the endodermal cell walls were doubled in thickness, greatly enhancing their retention capacity to CuO NPs. Taken together, the above findings suggest that CuO NPs have concentration-dependent effects on lettuce roots, which are associated with plant tolerance and mediated by RCW remodeling. [Display omitted] ● 5 mg L−1 CuO NPs enhanced root elongation of lettuce by root cell wall (RCW) loosening. ● 450 mg L−1 CuO NPs triggered RCW polysaccharides modifications which made lettuce roots difficult to extend. ● The encoding genes related to RCW remolding participated in the response of lettuce to CuO NPs. [ABSTRACT FROM AUTHOR]

The scarcity of fresh water has forced farmers to use saline water (SW) for irrigation. It is important to understand the response of the soil microbial community and diversity to saline irrigation water. The objective of this study was to determine the effects of irrigation water salinity and nitrogen fertilization rates on soil physicochemical properties, microbial activity, microbial biomass, and microbial functional diversity. The field experiment consisted of a factorial design with three levels of irrigation water salinity (electrical conductivities (ECs) of 0.35, 4.61 or 8.04 dS m−1) and two nitrogen rates (0 and 360 kg N ha−1). The results showed that the 4.61 and 8.04 dS m−1treatments both reduced soil microbial biomass C (MBC), microbial biomass N (MBN), basal respiration, total phospholipid fatty acid (PLFA), bacterial PLFA, fungal PLFA, and fungal:bacterial ratios. In contrast, the SW treatments increased the MBC:MBN ratio. Nitrogen fertilization increased soil MBC, MBN, basal respiration, total PLFA, bacterial PLFA, and gram-negative bacterial PLFA. In contrast,Nfertilization decreased gram-positive bacterial PLFA, fungal PLFA, and fungal:bacterial ratios. Average well color development, Richness, and Shannon's Index were always lowest in the 8.04 dS m−1treatment. Carbon utilization patterns in the 8.04 dS m−1treatment were different from those in the 0.35 dS m−1treatment. In conclusion, five years of irrigation with brackish or SW reduced the soil microbial biomass, activity, and functional diversity, which may cause the deterioration of soil quality. Thus, the high-salinity water (EC > 4.61 dS m−1) is not appropriate as a single irrigation water resource. ProperNfertilizer input may overcome some of the negative effects of salinity on soil microbial. [ABSTRACT FROM AUTHOR]

Emissions of the greenhouse gas nitrous oxide (N 2 O) from soil are sensitive to many factors including temperature, nutrient status, pH and bulk-density. Interactions among these are complex, particularly in agricultural systems where fertilizer-addition has interactive influences across many soil properties. Under laboratory conditions, the temperature sensitivity of N 2 O emissions, as measured by Q 10 values (fractional change in rate with a 10 °C increase in temperature), was higher in soils receiving long-term fertilizer addition compared with control. Different fertilization regimes significantly influenced the emission pathways. Application of manure increased the proportion of potential N 2 O derived from denitrification although the incubation condition used in the present study might not be favorable for anaerobic denitrification. The abundance of archaeal amoA gene copies increased under all fertilizer treatments, but that of bacterial amoA only increased under mineral (NPK) fertilization. Meanwhile, abundance of nirS , nirK and nosZ only increased under OM and MNPK fertilization. T-RFLP analyses showed that both ammonia oxidizing and denitrifier community structures were altered by fertilization, but only the nirS community structure was sensitive to temperature change. Furthermore, a strong correlation was observed between nirS gene abundance and potential N 2 O emissions. Relationships between AOA, nirK gene abundances and potential N 2 O emission were significant but relatively weak. PLS path model revealed that besides direct effect, potential N 2 O emission was also indirectly influenced by temperature through mediation of NH 4 + concentration and nirS -type denitrifier. Our work suggests that warming-induced elevation of potential N 2 O emission could be strengthened by long-term application of fertilizers, especially organic manure, via shifting community abundance and structure of nirS -type denitrifier. [ABSTRACT FROM AUTHOR]

Background and aims: We investigated the effects of silicon (Si) on chlorophyll concentration, photosynthesis, leaf chloroplast ultrastructure, and expression of genes involved in photosynthesis to elucidate the mechanisms through which Si mediated alleviation of manganese (Mn) toxicity in rice ( Oryza sativa L.). Methods: Rice seedlings were grown hydroponically with normal Mn (6.7 μM) or high Mn (2 mM) concentrations, both with (1.5 mM) and without Si supplementation. Leaf chloroplast ultrastructure was observed by scanning and transmission electron microscopy. Differentially expressed genes relating to photosynthesis were identified by high-throughput sequencing, and their relative expression levels were evaluated by real-time quantitative PCR. Results: Chlorophyll and carotenoid concentrations and net photosynthesis decreased with chloroplast degradation under high Mn stress. High Mn concentrations may have inhibited photosynthesis through several mechanisms, including suppressing chlorophyll and ATP synthesis, decreasing light-harvesting processes, impairing photosystem I (PSI) stability and structure, and slowing activity of phosphoribulokinase. Si enhanced Mn tolerance efficiently by increasing chlorophyll concentration, light-use efficiency, and ATP concentration as well as by stabilizing the structure of PSI and promoting CO assimilation. Conclusions: Our findings suggest active involvement of Si in Mn detoxification, ranging from physiological responses to gene expression. [ABSTRACT FROM AUTHOR]

Interspecific competition between ammonia-oxidizing archaea (AOA) and bacteria (AOB) has been documented, however, its significance in niche differentiation between these nitrifiers under ammonia-rich conditions remains elusive. A network-oriented microcosm incubation study was established to improve our understanding of their interspecific competition. A high ammonium concentration was maintained during the incubation by regularly supplementing urea, and the growth of AOB was retarded to different extents using the AOB inhibitors 1-octyne (OC) and 3,4-dimethylpyrazole phosphate (DMPP) as amendments. In parallel, a 13CO 2 -stable isotope probing (SIP) incubation study was conducted to investigate the metabolic activity of AOA and AOB under ammonium-rich conditions, with and without DMPP amendment. The results of the network-oriented microcosm incubation indicated that the growth of AOA was highly and negatively correlated with the growth of AOB (r = −0.94, P < 0.001). Network analysis of the whole prokaryotes showed that the majority of AOA phylotypes formed a module independent of AOB phylotypes, indicating their distinct niche preferences. In another distinctive module, we found the remaining AOA to have a coexclusion pattern with AOB, indicating a competitive relationship and a positive connection between AOB and many taxa capable of nitrite/nitrate metabolism, in particular denitrification. The SIP study confirmed that all AOA and AOB phylotypes retained in the network were autotrophically active. It was also shown that the phylotype susceptible to AOB competition was closely related to Nitrososphaera viennensis EN76. Overall, the results demonstrate that both niche preference and interspecific competition contribute to niche partitioning between AOA and AOB. Our results also showed that a tight connection between AOB and other nitrogen-cycling microorganisms may be responsible for substantial nitrogen loss. • Interspecific competition contributes to niche differentiation between AOA and AOB. • Phylotypes related to AOA Nitrososphaera viennesis are sensitive to interspecific competition. • 1-ocytne partially inhibits AOB due to restricted diffusion in the soil matrix. [ABSTRACT FROM AUTHOR]

Single-crystal gallium nitride (GaN) is considered as the key to future high-performance light emitters and power devices. Nevertheless, a mixed phase with micro twins often exists in GaN films. The formation of twin strongly affects the electronic properties of GaN-based devices. Based on the molecular dynamics (MD) simulation, we built a perfect nano-twinned cubic GaN (NT-cGaN) and created a solid-liquid (S/L) model in order to study the growth characteristics of the NT-cGaN at different isothermal temperatures. We observed an interesting dislocation loop (DL) in some systems. Our work not only reveals the formation process of DLs and its effect on mechanical properties, but also proposes some parameters to describe the length and shape of DLs. The results indicated that a perfect DL is coalesced by other dislocation lines after some dislocation reactions. A system with a DL is more stable than a system with a dislocation network (DN), and the length and shape of the DLs are closely relative to the isothermal time and temperatures. Moreover, increasing the isothermal time and temperatures can relieve the DL. In general, understanding nucleation and coalescence of dislocations is crucial in decreasing the dislocation density in a GaN crystal. [ABSTRACT FROM AUTHOR]

Preferable inorganic fertilization over the last decades has led to fertility degradation of black soil in Northeast China. However, how fertilization regimes impact denitrification and its related bacterial community in this soil type is still unclear. Here, taking advantage of a suit of molecular ecological tools in combination of assaying the potential denitrification (DP), we explored the variation of activity, community structure, and abundance of nirS and nirK denitrifiers under four different fertilization regimes, namely no fertilization control (N0M0), organic pig manure (N0M1), inorganic fertilization (N1M0), and combination of inorganic fertilizer and pig manure (N1M1). The results indicated that organic fertilization increased DP, but inorganic fertilization had no impacts. The increase of DP was mirrored by the shift of nirS denitrifiers' community structure but not by that of nirK denitrifiers'. Furthermore, the change of DP coincided with the variation of abundances of both denitrifiers. Shifts of community structure and abundance of nirS and nirK denitrifiers were correlated with the change of soil pH, total nitrogen (TN), organic matter (OM), C:P, total phosphorus (TP), and available phosphorus (Olsen P). Our results suggest that the change of DP under these four fertilization regimes was closely related to the shift of denitrifying bacteria communities resulting from the variation of properties in the black soil tested. [ABSTRACT FROM AUTHOR]

Background and aims: The role of polysaccharide modification in metal accumulation in hyperaccumulators is still unknown. Our aim was to compare the differences in the role of root cell-wall polysaccharides in cadmium (Cd) accumulation between hyperaccumulating (HE) and non-hyperaccumulating ecotype (NHE) of Sedm alfredii. Methods: Hydroponic experiments were performed to characterize root-to-shoot Cd translocation, cadmium species and polysaccharide modification in root cell-wall of S. alfredii using stable isotope tracing, X-ray absorption near edge structure and immunofluorescence localization techniques. Results: Cd absorbed was more readily available for transport to the shoots by the HE roots than by the NHE roots, which is confirmed by a 6-fold higher Cd concentration in xylem sap. Root Cd efflux originated mainly from the cell walls. The concentration of cell-wall polysaccharides and activity of pectin methylesterase were higher in the NHE than in the HE in the absence of Cd, and even higher in the presence of Cd. More pectins were methylated in the HE than in the NHE, indicating more free pectic acid residues in the NHE. The cell-wall-bound Cd was retained more tightly in the NHE than in the HE. Conclusions: Cadmium hyperaccumulation by HE of S. alfredii is associated with its enhanced Cd flux into the xylem, which is partly regulated by cell-wall polysaccharide modification in roots. [ABSTRACT FROM AUTHOR]

The impacts of long-term application of inorganic and organic fertilizers on the activity, community composition, and abundance of denitrifying bacteria in an aquic soil of Northeast China were analyzed in this study. Denitrifying taxa were characterized for their nitrite reductase genes, nirS and nirK . The results showed that addition of inorganic fertilizer to soil decreased potential denitrification enzyme activity (DEA) by 41.1%, and this effect was mirrored by a reduction (39.0%) in the nirS -, but not nirK -denitrifiers' abundance. Addition of organic fertilizer increased DEA by 41.3% but had no impact on the abundance of either nirS - or nirK -denitrifiers. Inorganic fertilization strongly altered the community structure of nirK but only marginally impacted the community structure of nirS -denitrifiers; organic fertilizer had no influence on the community structures of these two guilds. DEA was significantly correlated with community structure of nirK -denitrifiers, but not with community structure of nirS -denitrifiers and abundances of both nirK - and nirS -denitrifiers. Moreover, community structure of nirK -denitrifiers was significantly correlated with pH, while nirS -denitrifiers were impacted by soil pH, total phosphorus (TP), and Olsen phosphorus (Olsen P) status. Our results suggest that different influences of inorganic and organic fertilization on DP are linked to a distinct structural change of nirS - and nirK -denitrifying bacterial communities in this aquic brown soil. [ABSTRACT FROM AUTHOR]

The main objectives of this study were to elucidate the roles of silicon (Si) in alleviating the effects of 2 mM zinc (high Zn) stress on photosynthesis and its related gene expression levels in leaves of rice (Oryza sativa L.) grown hydroponically with high-Zn stress. The results showed that photosynthetic parameters, including net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration, chlorophyll concentration and the chlorophyll fluorescence, were decreased in rice exposed to high-Zn treatment. The leaf chloroplast structure was disordered under high-Zn stress, including uneven swelling, disintegrated and missing thylakoid membranes, and decreased starch granule size and number, which, however, were all counteracted by the addition of 1.5 mM Si. Furthermore, the expression levels of Os08g02630 (PsbY), Os05g48630 (PsaH), Os07g37030 (PetC), Os03g57120 (PetH), Os09g26810 and Os04g38410 decreased in Si-deprived plants under high-Zn stress. Nevertheless, the addition of 1.5 mM Si increased the expression levels of these genes in plants under high-Zn stress at 72 h, and the expression levels were higher in Si-treated plants than in Si-deprived plants. Therefore, we conclude that Si alleviates the Zn-induced damage to photosynthesis in rice. The decline of photosynthesis in Zn-stressed rice was attributed to stomatal limitation, and Si activated and regulated some photosynthesis-related genes in response to high-Zn stress, consequently increasing photosynthesis. [ABSTRACT FROM AUTHOR]

Microbial mechanism of in-situ remediation of arsenic (As) in As-contaminated paddy fields by silicon (Si) fertilization has been rarely reported, especially under continuous rice cultivation and Si applications. In this study, two Si fertilizers were applied for three phases in five consecutive rice seasons to investigate the long-lasting impacts on in-situ remediation of As, and the underpinning microbial mechanism of root-associated compartments (bulk soil, rhizosphere and endosphere) was explored using the last double-cropping rice. Repeated application of Si fertilizers as base manure had a long-lasting effect on reducing As concentrations in rice grains. Application of Si fertilizer at an adequate amount resulted in an extended in-situ remediation effect from endosphere to rhizosphere. The microbial diversity and richness in rhizosphere soil and endosphere were significantly impacted by Si fertilization, the effects depending on application doses and prolonged seasons. Si fertilization can immobilize As in the root or rhizosphere, and Fe concentrations and the As- and Fe-transforming microorganisms (i.e. Geobacteraceae) are the determinants of As uptake in rice. We recommend more extensive supplementation of Si fertilizer at a higher rate to decrease grain As concentration for in-situ remediation. This study sheds light on the microbial-mediated mechanism underlying Si fertilization effect on decreased As uptake in paddy fields. [Display omitted] • Si fertilization had a lasting effect on decreasing grain As concentrations. • Adequate Si extended in-situ remediation effect from endosphere to rhizosphere. • Si fertilization could depress the translocation and uptake of As. • Fe contents and As-/Fe-related microbes determined uptake and translocation of As. [ABSTRACT FROM AUTHOR]