Sm_2 Fe_(17) prepared by reduction-diffusion method needs to be washed with water to remove calcium oxide. Electrochemical corrosion occurs when Sm_2 Fe_(17) powder is in contact with liquid water. Corrosion mechanism...Sm_2 Fe_(17) prepared by reduction-diffusion method needs to be washed with water to remove calcium oxide. Electrochemical corrosion occurs when Sm_2 Fe_(17) powder is in contact with liquid water. Corrosion mechanism of H_2 O on Sm_2 Fe_(17) powder and nitrogenation process of corroded Sm_2 Fe_(17) were studied by analyzing the structure and morphology. It is indicated that the metallic hydroxide forms and deposits on the Sm_2 Fe_(17) powder surfaces during water corrosion. At the same time, oxygen and hydrogen enter the unit cell of Sm2 Fe_(17), causing a slight increase in Curie temperature. In the subsequent nitriding process,the hydroxide is dehydrated and hydrogen is desorbed. The resulting oxide reacts with Sm_2 Fe_(17)N_x to form a-Fe and Sm_2 O_3. Thermodynamic calculations using the HSC Chemistry 6.0 software indicate that the reaction can occur spontaneously. The effect of water corrosion on the magnetic properties of the nitride can be eliminated by hydrogen reduction prior to nitriding.展开更多
Nitrogenation of SmFelolVIo2 powders was performed in a self-made furnace under a high-purity N2 atmo- sphere up to 40 MPa at 500 ℃. Upon nitrogenation at atmospheric pressure, the lattice parameters a and c increase...Nitrogenation of SmFelolVIo2 powders was performed in a self-made furnace under a high-purity N2 atmo- sphere up to 40 MPa at 500 ℃. Upon nitrogenation at atmospheric pressure, the lattice parameters a and c increase by 0.5% and 2.7%, respectively, whereas the Curie temperature Tc increases from 519 to 633 K. With further increasing the nitrogenation pressure to 20 and 40 MPa, the 1：12 main phase starts to decompose and a large amount of Mo and a-Fe precipitates. This leads to variation of Mo concentration in the 1：12 phase and causes a sharp decrease in Tc and in the coercivity. The relative complex permittivity and permeability of paraffin-SmFeloMO2 composites show multi-resonant behavior. After nitrogenation, the magnetic loss of the powders decreases, which may originate from the influence of eddy currents due to the increase in the particle size.展开更多
The reaction kinetics between nitrogen gas and Nd(Fe, Mo)_(12) intermetallic compound has been studied. The relationship between the reaction temperature, the reaction time with average mass fraction of N in samples h...The reaction kinetics between nitrogen gas and Nd(Fe, Mo)_(12) intermetallic compound has been studied. The relationship between the reaction temperature, the reaction time with average mass fraction of N in samples have been measured. The activation energy of first step reaction, E_f,(18.2 kJ/mol), is smaller than E_s (64.6 kJ /mol) of the second step during which nitrogen diffusion in the range 400～550℃ can be represented by an activated interstitial diffusion process. Heating above 550℃ leads to disproportion of the compound into NdN and α-Fe and the permanent properties will be damaged greatly.展开更多
A comprehensive insight into the evolution and molecular structure of basic and neutral nitrogen compounds during the residue hydrotreating(RHT)process was gained through ESI(+)/ESI(-)FT-ICR MS analysis of the feedsto...A comprehensive insight into the evolution and molecular structure of basic and neutral nitrogen compounds during the residue hydrotreating(RHT)process was gained through ESI(+)/ESI(-)FT-ICR MS analysis of the feedstock and its hydrogenated samples,with hydrodenitrogenation(HDN)ratios of 15.9%-70.1%.This study revealed that carbazoles,characterized by a double bond equivalent(DBE)of 9-11,were the refractory neutral nitrogen compounds during the RHT process.Their recalcitrant nature was primarily due to their low aromaticity and high steric hindrance.Conversely,quinolines(DBEs 7 to 9)were the most abundant basic nitrogen compounds.Through a meticulous analysis of DBE evolution,we revealed the intricate reaction mechanisms of benzocarbazoles and dibenzocarbazoles in residual oil,highlighting the crucial role of quinolines as key intermediates in eliminating these compounds.Interestingly,nitrogen compounds with either low or high carbon numbers(for a given DBE)exhibited higher reactivity than those with medium carbon numbers,which can be attributed to the low steric hindrance resulting from short alkyl chains and more naphthenic-aromatic structures,respectively.After hydrotreatment,the molecular structures of the most refractory or abundant nitrogen compounds could consist of two main types:those with multiple naphthenic-aromatic rings and those with long side chains near the nitrogen atom.This research has revealed nitrogen compounds'evolutionary mechanisms and refractory nature,and the molecular structure of the most resistant or abundant basic and neutral nitrogen compounds,providing a deeper understanding of the HDN process and ultimately paving the way for the rational RHT catalyst design and process development.展开更多
Nitric oxide(NO)is a gaseous molecule produced by 3 different NO synthase(NOS)isoforms:Neural/brain NOS(nNOS/bNOS,type 1),endothelial NOS(eNOS,type 3)and inducible NOS(type 2).Type 1 and 3 NOS are constitutively expre...Nitric oxide(NO)is a gaseous molecule produced by 3 different NO synthase(NOS)isoforms:Neural/brain NOS(nNOS/bNOS,type 1),endothelial NOS(eNOS,type 3)and inducible NOS(type 2).Type 1 and 3 NOS are constitutively expressed.NO can serve different purposes:As a vasoactive molecule,as a neurotransmitter or as an immunomodulator.It plays a key role in cerebral ischemia/reperfusion injury(CIRI).Hypoxic episodes simulate the production of oxygen free radicals,leading to mitochondrial and phospholipid damage.Upon reperfusion,increased levels of oxygen trigger oxide synthases;whose products are associated with neuronal damage by promoting lipid peroxidation,nitrosylation and excitotoxicity.Molecular pathways in CIRI can be altered by NOS.Neuroprotective effects are observed with eNOS activity.While nNOS interplay is prone to endothelial inflammation,oxidative stress and apoptosis.Therefore,nNOS appears to be detrimental.The interaction between NO and other free radicals develops peroxynitrite;which is a cytotoxic agent.It plays a main role in the likelihood of hemorrhagic events by tissue plasminogen activator(t-PA).Peroxynitrite scavengers are currently being studied as potential targets to prevent hemorrhagic transformation in CIRI.展开更多
The increase in soil temperature associated with climate change has introduced considerable challenges to crop production.Split nitrogen application(SN)represents a potential strategy for improving crop nitrogen use e...The increase in soil temperature associated with climate change has introduced considerable challenges to crop production.Split nitrogen application(SN)represents a potential strategy for improving crop nitrogen use efficiency and enhancing crop stress resistance.Nevertheless,the precise interaction between soil warming(SW)and SN remains unclear.In order to ascertain the impact of SW on maize growth and whether SN can improve the tolerance of maize to SW,a two-year field experiment was conducted(2022-2023).The aim was to examine the influence of two SW ranges(MT,warming 1.40℃;HT,warming 2.75℃)and two nitrogen application methods(N1,one-time basal application of nitrogen fertilizer;N2,one third of base nitrogen fertilizer+two thirds of jointing stage supplemental nitrogen fertilizer)on maize root growth,photosynthetic characteristics,nitrogen use efficiency,and yield.The results demonstrated that SW impeded root growth and precipitated the premature aging of maize leaves following anthesis,particularly in the HT,which led to a notable reduction in maize yield.In comparison to N1,SN has been shown to increase root length density by 8.54%,root bleeding rate by 8.57%,and enhance root distribution ratio in the middle soil layers(20-60 cm).The interaction between SW and SN had a notable impact on maize growth and yield.The SN improved the absorption and utilization efficiency of nitrogen by promoting root development and downward canopy growth,thus improving the tolerance of maize to SW at the later stage of growth.In particular,the N2HT resulted in a 14.51%increase in the photosynthetic rate,a 18.58%increase in nitrogen absorption efficiency,and a 18.32%increase in maize yield compared with N1HT.It can be posited that the SN represents a viable nitrogen management measure with the potential to enhance maize tolerance to soil high-temperature stress.展开更多
An efficient KI catalyzed nitrogenation of aldehydes and alcohols for the direct synthesis of carbamoyl azides and ureas via a radical process has been developed. The simple operating procedures, the readily available...An efficient KI catalyzed nitrogenation of aldehydes and alcohols for the direct synthesis of carbamoyl azides and ureas via a radical process has been developed. The simple operating procedures, the readily available starting materials including aldehydes, alcohols and amines, as well as the utility of the products all make this strategy very attractive.展开更多
Nitrogen(N)uptake is regulated by water availability,and a water deficit can limit crop N responses by reducing N uptake and utilization.The complex and multifaceted interplay between water availability and the crop N...Nitrogen(N)uptake is regulated by water availability,and a water deficit can limit crop N responses by reducing N uptake and utilization.The complex and multifaceted interplay between water availability and the crop N response makes it difficult to predict and quantify the effect of water deficit on crop N status.The nitrogen nutrition index(NNI)has been widely used to accurately diagnose crop N status and to evaluate the effectiveness of N application.The decline of NNI under water-limiting conditions has been documented,although the underlying mechanism governing this decline is not fully understood.This study aimed to elucidate the reason for the decline of NNI under waterlimiting conditions and to provide insights into the accurate utilization of NNI for assessing crop N status under different water-N interaction treatments.Rainout shelter experiments were conducted over three growing seasons from 2018 to 2021 under different N(75 and 225 kg N ha^(-1),low N and high N)and water(120 to 510 mm,W0 to W3)co-limitation treatments.Plant N accumulation,shoot biomass(SB),plant N concentration(%N),soil nitrate-N content,actual evapotranspiration(ET_a),and yield were recorded at the stem elongation,booting,anthesis and grain filling stages.Compared to W0,W1 to W3 treatments exhibited NNI values that were greater by 10.2 to 20.5%,12.6to 24.8%,14 to 24.8%,and 16.8 to 24.8%at stem elongation,booting,anthesis,and grain filling,respectively,across the 2018-2021 seasons.This decline in NNI under water-limiting conditions stemmed from two main factors.First,reduced ET_(a) and SB led to a greater critical N concentration(%N_(c))under water-limiting conditions,which contributed to the decline in NNI primarily under high N conditions.Second,changes in plant%N played a more significant role under low N conditions.Plant N accumulation exhibited a positive allometric relationship with SB and a negative relationship with soil nitrate-N content under water-limiting conditions,indicating co-regulation by SB and the soil nitrate-N content.However,this regulation was influenced by water availability.Plant N accumulation sourced from the soil nitrate-N content reflects soil N availability.Greater soil water availability facilitated greater absorption of soil nitrate-N into the plants,leading to a positive correlation between plant N accumulation and ET_(a)across the different water-N interaction treatments.Therefore,considering the impact of soil water availability is crucial when assessing soil N availability under water-limiting conditions.The findings of this study provide valuable insights into the factors contributing to the decline in NNI among different water-N interaction treatments and can contribute to the more accurate utilization of NNI for assessing winter wheat N status.展开更多
Amides are among the fundamental chemicals in organic chemistry.Compared to other carbonyl functional groups,the transformation of amide is relatively difficult and remains a challenge.The traditional deconstruction t...Amides are among the fundamental chemicals in organic chemistry.Compared to other carbonyl functional groups,the transformation of amide is relatively difficult and remains a challenge.The traditional deconstruction transformations of amides to other functional products are usually limited to twisted or electronically activated amides.Herein,we describe a direct nitrogenation approach to convert amides into nitriles.This chemistry provides a novel amide transformation pathway via both C–C and C–N bond cleavage.Interestingly,the simple,readily available,and inexpensive inorganic salt NaNO2 is successfully employed as a nitrogen source in this organic N-incorporation process.Applications of this study are demonstrated through the latestage modification of drug and natural product derivatives.展开更多
Nitrogen removal from domestic sewage is usually limited by insufficient carbon source and electron donor.An economical solid carbon source was developed by composition of polyvinyl alcohol,sodium alginate,and corncob...Nitrogen removal from domestic sewage is usually limited by insufficient carbon source and electron donor.An economical solid carbon source was developed by composition of polyvinyl alcohol,sodium alginate,and corncob,which was utilized as external carbon source in the anaerobic anoxic oxic(AAO)-biofilter for the treatment of low carbon-to-nitrogen ratio domestic sewage,and the nitrogen removal was remarkably improved from 63.2%to 96.5%.Furthermore,the effluent chemical oxygen demand maintained at 35 mg/L or even lower,and the total nitrogenwas reduced to less than 2mg/L.Metagenomic analysis demonstrated that the microbial communities responsible for potential denitrification and organic matter degradation in both AAO and the biofilter reactors were mainly composed of Proteobacteria and Bacteroides,respectively.The solid carbon source addition resulted in relatively high abundance of functional enzymes responsible for NO_(3)^(−)-N to NO_(2)^(−)-N con-version in both AAO and the biofilter reactors,thus enabled stable reaction.The carbon source addition during glycolysis primarily led to the increase of genes associated with the metabolic conversion of fructose 1.6P2 to glycerol-3P The reactor maintained high abun-dance of genes related to the tricarboxylic acid cycle,and then guaranteed efficient carbon metabolism.The results indicate that the composite carbon source is feasible for denitri-fication enhancement of AAO-biofilter,which contribute to the theoretical foundation for practical nitrogen removal application.展开更多
The trade-off between yield and environmental effects caused by nitrogen fertilizer application is an important issue in wheat production.A reduction in fertile florets is one of the main reasons for the lower yields ...The trade-off between yield and environmental effects caused by nitrogen fertilizer application is an important issue in wheat production.A reduction in fertile florets is one of the main reasons for the lower yields under low nitrogen application rates.Brassinosteroids(BRs)have been found to play a role in nitrogen-induced rice spikelet degeneration.However,whether BRs play a role in wheat floret development and the mechanisms involved are not clear.Therefore,a nitrogen gradient experiment and exogenous spraying experiment were conducted to investigate the role and mechanism of BRs in wheat floret development under low nitrogen stress.The results showed that as the nitrogen application decreased,the endogenous BRs content of the spikes decreased,photosynthesis weakened,and total carbon,soluble sugar and starch in the spikes decreased,leading to a reduction in the number of fertile florets.Under low nitrogen stress,exogenous spraying of 24-epibrassinolide promoted photosynthesis,and stimulated stem fructan hydrolysis and the utilization and storage of sucrose in spikes,which directed more carbohydrates to the spikes and increased the number of fertile florets.In conclusion,BRs mediate the effects of nitrogen fertilizer on wheat floret development,and under low nitrogen stress,foliar spraying of 24-epibrassinolide promotes the flow of carbohydrates from the stem to the spikes,alleviating wheat floret degeneration.展开更多
The thermochemical non-equilibrium phenomena encountered by hypersonic vehicles present significant challenges in their design.To investigate the thermochemical reaction flow behind shock waves,the non-equilibrium rad...The thermochemical non-equilibrium phenomena encountered by hypersonic vehicles present significant challenges in their design.To investigate the thermochemical reaction flow behind shock waves,the non-equilibrium radiation in the visible range using a shock tube was studied.Experiments were conducted with a shock velocity of 4.7 km/s,using nitrogen at a pressure of 20 Pa.To address measurement difficulties associated with weak radiation,a special square section shock tube with a side length of 380 mm was utilized.A high-speed camera characterized the shock wave’s morphology,and a spectrograph and a monochromator captured the radiation.The spectra were analyzed,and the numerical spectra were compared with experimental results,showing a close match.Temperature changes behind the shock wave were obtained and compared with numerical predictions.The findings indicate that the vibrational temperatures are overestimated,while the vibrational relaxation time is likely underestimated,due to the oversimplified portrayals of the non-equilibrium relaxation process in the models.Additionally,both experimental and simulated time-resolved profiles of radiation intensity at specific wavelengths were analyzed.The gathered data aims to enhance computational fluid dynamics codes and radiation models,improving their predictive accuracy.展开更多
Ammonia and nitric acid,versatile industrial feedstocks,and burgeoning clean energy vectors hold immense promise for sustainable development.However,Haber–Bosch and Ostwald processes,which generates carbon dioxide as...Ammonia and nitric acid,versatile industrial feedstocks,and burgeoning clean energy vectors hold immense promise for sustainable development.However,Haber–Bosch and Ostwald processes,which generates carbon dioxide as massive by-product,contribute to greenhouse effects and pose environmental challenges.Thus,the pursuit of nitrogen fixation through carbon–neutral pathways under benign conditions is a frontier of scientific topics,with the harnessing of solar energy emerging as an enticing and viable option.This review delves into the refinement strategies for scale-up mild photocatalytic nitrogen fixation,fields ripe with potential for innovation.The narrative is centered on enhancing the intrinsic capabilities of catalysts to surmount current efficiency barriers.Key focus areas include the in-depth exploration of fundamental mechanisms underpinning photocatalytic procedures,rational element selection,and functional planning,state-of-the-art experimental protocols for understanding photo-fixation processes,valid photocatalytic activity evaluation,and the rational design of catalysts.Furthermore,the review offers a suite of forward-looking recommendations aimed at propelling the advancement of mild nitrogen photo-fixation.It scrutinizes the existing challenges and prospects within this burgeoning domain,aspiring to equip researchers with insightful perspectives that can catalyze the evolution of cutting-edge nitrogen fixation methodologies and steer the development of next-generation photocatalytic systems.展开更多
Plant synthetic biology has emerged as a transformative field in agriculture,offering innovative solutions to enhance food security,provide resilience to climate change,and transition to sustainable farming practices....Plant synthetic biology has emerged as a transformative field in agriculture,offering innovative solutions to enhance food security,provide resilience to climate change,and transition to sustainable farming practices.By integrating advanced genetic tools,computational modeling,and systems biology,researchers can precisely modify plant genomes to enhance traits such as yield,stress tolerance,and nutrient use efficiency.The ability to design plants with specific characteristics tailored to diverse environmental conditions and agricultural needs holds great potential to address global food security challenges.Here,we highlight recent advancements and applications of plant synthetic biology in agriculture,focusing on key areas such as photosynthetic efficiency,nitrogen fixation,drought tolerance,pathogen resistance,nutrient use efficiency,biofortification,climate resilience,microbiology engineering,synthetic plant genomes,and the integration of artificial intelligence with synthetic biology.These innovations aim to maximize resource use efficiency,reduce reliance on external inputs,and mitigate environmental impacts associated with conventional agricultural practices.Despite challenges related to regulatory approval and public acceptance,the integration of synthetic biology in agriculture holds immense promise for creating more resilient and sustainable agricultural systems,contributing to global food security and environmental sustainability.Rigorous multi-field testing of these approaches will undoubtedly be required to ensure reproducibility.展开更多
HONO is a critical precursor of•OH,but its sources are controversial due to its complex formation mechanism.This study conducted comprehensive observations in Zhengzhou from April 26 to May 11,2022.Low NO_(x)concentra...HONO is a critical precursor of•OH,but its sources are controversial due to its complex formation mechanism.This study conducted comprehensive observations in Zhengzhou from April 26 to May 11,2022.Low NO_(x)concentrations were observed during the Covid epidemic period(EP)(10.4±3.0 ppb),compared to the pre-epidemic period(PEP)(12.5±3.8 ppb).The mean HONO concentration during EP(0.53±0.34 ppb)was 0.09 ppb lower than that during PEP(0.62±0.53 ppb).The decrease in HONO concentration during EP came mainly at night due to the reduction in the direct emission(P_(emi))(0.03 ppb/hr),the homogeneous reaction between•OHandNO(P_(OH+NO))(0.02 ppb/hr),and the heterogeneous conversion of NO_(2)on the ground(0.01 ppb/hr).Notably,there was no significant change in daytime HONO concentration.The daytime HONO budget indicated that the primary HONO sources during PEP were the nitrate photolysis(P_(nitrate)),followed by the P_(OH+NO),Pemi,the photo-enhanced reaction of NO_(2)on the ground(P_(ground+hv))and aerosol surface(Paerosol+hv).The primary HONO sources were Pnitrate,POH+NO,P_(emi),and_(Paerosol+hv)during EP,respectively.The missing source has a high correlation with solar radiation,there might be other photo-related HONO sources or the contributions of photosensitized reactions were underestimated.In the extremely underestimated cases,HONO production rates fromthe P_(nitrate),P_(ground+hv),and Paerosol+hv increased by 0.17,0.10,and 0.10 ppb/hr during PEP,0.23,0.13,and 0.16 ppb/hr during EP,and P_(nitrate)was still the primary source during both PEP and EP.展开更多
The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by deposit...The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by depositing Pt and RuO_(2)particles onto g-C_(3)N_(4).The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and UV–vis diffuse reflectance spectrometer(UV–vis DRS).The photocatalysts were then applied to the removal of both NH_(4)^(+)-N and bacteria from simulated mariculture wastewater.The results clarified that the removals of both NH_(4)^(+)-N and bacteria were in the sequence of g-C_(3)N_(4)<RuO_(2)/g-C_(3)N_(4)<Pt/g-C_(3)N_(4)<Pt/RuO_(2)/g-C_(3)N_(4).This magnificent photocatalytic ability of Pt/RuO_(2)/g-C_(3)N_(4)can be interpreted by the transfer of holes from g-C_(3)N_(4)to RuO_(2)to facilitate the in situ generation of HClO from Cl^(−)in wastewater,while Pt extracts photogenerated electrons for H_(2)formation to enhance the reaction.The removal of NH_(4)^(+)-N and disinfection effect were more pronounced in simulated seawater than in purewater.The removal efficiency ofNH_(4)^(+)-N increases with an increase in pH of wastewater,while the bactericidal effect was more significant under a lower pH in a pH range of 6–9.In actual seawater aquaculture wastewater,Pt/RuO_(2)/g-C_(3)N_(4)still exhibits effective removal efficiency of NH_(4)^(+)-N and bactericidal performance under sunlight.This study provides an alternative avenue for removement of NH_(4)^(+)-N and bacteria from saline waters under sunlight.展开更多
In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-dept...In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-depth exploration of photocatalytic reaction systems with fewer constraints imposed by surface chemistry.Typically,the isotropy of a specific facet provides a perfect support for studying heteroatom doping.Herein,this work delves into the intrinsic catalytic sites for photocatalytic nitrogen fixation in iron-doped lithium tantalate single crystals.The presence of iron not only modifies the electronic structure of lithium tantalate,improving its light absorption capacity,but also functions as an active site for the nitrogen adsorption and activation.The photocatalytic ammonia production rate of the iron-doped lithium tantalate in pure water is maximum 26.95μg cm^(−2)h^(−1),which is three times higher than that of undoped lithium tantalate.The combination of first-principles simulations with in situ characterizations confirms that iron doping promotes the rate-determining step and changes the pathway of hydrogenation to associative alternating.This study provides a new perspective on in-depth investigation of intrinsic catalytic active sites in photocatalysis and other catalytic processes.展开更多
To promote the growth of cutting seeding of poplar(Populus L.),nitrogen(N)fertilizer and surface weed managements were required.We here conducted a pot experiment to examine the effects of natural vegetation,barnyardg...To promote the growth of cutting seeding of poplar(Populus L.),nitrogen(N)fertilizer and surface weed managements were required.We here conducted a pot experiment to examine the effects of natural vegetation,barnyardgrass(Echinochloa Beauv.),and sesbania(Sesbania cannabina pers.)on the growth of poplar cutting seedlings,soil properties,and ammonia(NH3)volatilization under three N inputs(0,0.5,and 1.5 g/pot,i.e.,N0,N0.5,and N1,respectively).Results showed that N application promoted the growth of poplar cutting seedlings,including plant height,ground diameter,and biomass,compared with N0 treatment.Moreover,under N0,sesbania significantly increased the plant height by 87.1%,barnyardgrass and sesbania significantly increased the ground diameter(16.2%and 51.5%),and biomass(67.4%and 74.7%)of poplar cutting seedlings,compared with natural vegetation management.Compared to natural vegetation,soil organic matter(SOM)of barnyardgrass and sesbania covered soil significantly increased by 12.4%and 18.7%at N1,respectively.In addition,soil total N(TN)content was significantly increased by 15.8%in barnyardgrass planted at N0.The soil ammonium N(NH_(4)^(+)-N)content decreased with the planting of barnyardgrass and sesbania across all levels of N application.At N0.5,the nitrate N(NO_(3)^(−)-N)content of soil planted with barnyardgrass significantly increased compared to both the natural vegetation and the sesbania groups.Compared to the natural vegetation,the soil available phosphorus(AP)content of the barnyardgrass group significantly increasing by 78.8%at N0.5,soil available potassium(AK)content was significantly reduced by 12.5%in the sesbania group at N0 and increased by 24.1%in the barnyardgrass group at N1.We found that cumulative NH3 emissions were significantly higher in all treatment groups at the N1 level than that at the N0.5 level,while the differences among the three plants treated were not significant.The results suggest that both barnyardgrass and sesbania promote seedling growth in the short term,while also increase certain properties.Therefore,effective herb management during the seedling stage is recommended in nurseries to support seedling growth and retain soil fertility.展开更多
A four-year field experiment was conducted with two cultivars and four N rate to investigate the spatiotemporal characteristics of leaf senescence in maize after silking and its response to N fertilizer rates on them,...A four-year field experiment was conducted with two cultivars and four N rate to investigate the spatiotemporal characteristics of leaf senescence in maize after silking and its response to N fertilizer rates on them,as well as to reveal the differences in post-silking chlorophyll degradation between low-N-tolerant cultivars.The results showed that the order of leaf senescence after silking in maize was lower leaf>upper leaf>ear leaf,leaf tip>middle>base.Increasing N fertilizer down-regulated the expression of ZmCLH2 and ZmPPH in the leaves at 10-30 d after silking,reducing CLH and PPH activities,thereby delaying the leaf senescence.These effects were more prominent in low-N-sensitive cultivar Xianyu 508(XY508)than in low-N-tolerant cultivar Zhenghong 311(ZH311),especially in the lower leaves and leaf tip.Under low N condition,leaf yellowing and chlorophyll degradation occurred later and slower in ZH311 than in XY508.This resulted in a higher post-silking dry matter accumulation and grain yield in ZH311,which may be one of the important physiological bases of low nitrogen tolerant cultivars.Future research should focus on developing low-N-tolerant maize cultivars with slower leaf senescence near the ear after silking.展开更多
基金Project supported by Natural Science Foundation of Ningbo,China(2017A610079)Technology Innovation&Achievement Industrialization Project of Ningbo China(2014B11010)
文摘Sm_2 Fe_(17) prepared by reduction-diffusion method needs to be washed with water to remove calcium oxide. Electrochemical corrosion occurs when Sm_2 Fe_(17) powder is in contact with liquid water. Corrosion mechanism of H_2 O on Sm_2 Fe_(17) powder and nitrogenation process of corroded Sm_2 Fe_(17) were studied by analyzing the structure and morphology. It is indicated that the metallic hydroxide forms and deposits on the Sm_2 Fe_(17) powder surfaces during water corrosion. At the same time, oxygen and hydrogen enter the unit cell of Sm2 Fe_(17), causing a slight increase in Curie temperature. In the subsequent nitriding process,the hydroxide is dehydrated and hydrogen is desorbed. The resulting oxide reacts with Sm_2 Fe_(17)N_x to form a-Fe and Sm_2 O_3. Thermodynamic calculations using the HSC Chemistry 6.0 software indicate that the reaction can occur spontaneously. The effect of water corrosion on the magnetic properties of the nitride can be eliminated by hydrogen reduction prior to nitriding.
基金financially supported by the National Natural Science Foundation of China (No. 51261001)Liaoning Provincial Natural Science Foundation (No. 2013020105)Shenyang Science and Technology Foundation (No. F13-316-139)
文摘Nitrogenation of SmFelolVIo2 powders was performed in a self-made furnace under a high-purity N2 atmo- sphere up to 40 MPa at 500 ℃. Upon nitrogenation at atmospheric pressure, the lattice parameters a and c increase by 0.5% and 2.7%, respectively, whereas the Curie temperature Tc increases from 519 to 633 K. With further increasing the nitrogenation pressure to 20 and 40 MPa, the 1：12 main phase starts to decompose and a large amount of Mo and a-Fe precipitates. This leads to variation of Mo concentration in the 1：12 phase and causes a sharp decrease in Tc and in the coercivity. The relative complex permittivity and permeability of paraffin-SmFeloMO2 composites show multi-resonant behavior. After nitrogenation, the magnetic loss of the powders decreases, which may originate from the influence of eddy currents due to the increase in the particle size.
文摘The reaction kinetics between nitrogen gas and Nd(Fe, Mo)_(12) intermetallic compound has been studied. The relationship between the reaction temperature, the reaction time with average mass fraction of N in samples have been measured. The activation energy of first step reaction, E_f,(18.2 kJ/mol), is smaller than E_s (64.6 kJ /mol) of the second step during which nitrogen diffusion in the range 400～550℃ can be represented by an activated interstitial diffusion process. Heating above 550℃ leads to disproportion of the compound into NdN and α-Fe and the permanent properties will be damaged greatly.
基金the financial support from the National Key Research and Development Program of China(2021YFA1501204)the project of SINOPEC RIPP Co.Ltd(PR20230230)。
文摘A comprehensive insight into the evolution and molecular structure of basic and neutral nitrogen compounds during the residue hydrotreating(RHT)process was gained through ESI(+)/ESI(-)FT-ICR MS analysis of the feedstock and its hydrogenated samples,with hydrodenitrogenation(HDN)ratios of 15.9%-70.1%.This study revealed that carbazoles,characterized by a double bond equivalent(DBE)of 9-11,were the refractory neutral nitrogen compounds during the RHT process.Their recalcitrant nature was primarily due to their low aromaticity and high steric hindrance.Conversely,quinolines(DBEs 7 to 9)were the most abundant basic nitrogen compounds.Through a meticulous analysis of DBE evolution,we revealed the intricate reaction mechanisms of benzocarbazoles and dibenzocarbazoles in residual oil,highlighting the crucial role of quinolines as key intermediates in eliminating these compounds.Interestingly,nitrogen compounds with either low or high carbon numbers(for a given DBE)exhibited higher reactivity than those with medium carbon numbers,which can be attributed to the low steric hindrance resulting from short alkyl chains and more naphthenic-aromatic structures,respectively.After hydrotreatment,the molecular structures of the most refractory or abundant nitrogen compounds could consist of two main types:those with multiple naphthenic-aromatic rings and those with long side chains near the nitrogen atom.This research has revealed nitrogen compounds'evolutionary mechanisms and refractory nature,and the molecular structure of the most resistant or abundant basic and neutral nitrogen compounds,providing a deeper understanding of the HDN process and ultimately paving the way for the rational RHT catalyst design and process development.
文摘Nitric oxide(NO)is a gaseous molecule produced by 3 different NO synthase(NOS)isoforms:Neural/brain NOS(nNOS/bNOS,type 1),endothelial NOS(eNOS,type 3)and inducible NOS(type 2).Type 1 and 3 NOS are constitutively expressed.NO can serve different purposes:As a vasoactive molecule,as a neurotransmitter or as an immunomodulator.It plays a key role in cerebral ischemia/reperfusion injury(CIRI).Hypoxic episodes simulate the production of oxygen free radicals,leading to mitochondrial and phospholipid damage.Upon reperfusion,increased levels of oxygen trigger oxide synthases;whose products are associated with neuronal damage by promoting lipid peroxidation,nitrosylation and excitotoxicity.Molecular pathways in CIRI can be altered by NOS.Neuroprotective effects are observed with eNOS activity.While nNOS interplay is prone to endothelial inflammation,oxidative stress and apoptosis.Therefore,nNOS appears to be detrimental.The interaction between NO and other free radicals develops peroxynitrite;which is a cytotoxic agent.It plays a main role in the likelihood of hemorrhagic events by tissue plasminogen activator(t-PA).Peroxynitrite scavengers are currently being studied as potential targets to prevent hemorrhagic transformation in CIRI.
基金supported by the Natural Science Fund of China(31771724)the Key Research and Development Project of Shaanxi Province(2024NC-ZDCYL-01-10).
文摘The increase in soil temperature associated with climate change has introduced considerable challenges to crop production.Split nitrogen application(SN)represents a potential strategy for improving crop nitrogen use efficiency and enhancing crop stress resistance.Nevertheless,the precise interaction between soil warming(SW)and SN remains unclear.In order to ascertain the impact of SW on maize growth and whether SN can improve the tolerance of maize to SW,a two-year field experiment was conducted(2022-2023).The aim was to examine the influence of two SW ranges(MT,warming 1.40℃;HT,warming 2.75℃)and two nitrogen application methods(N1,one-time basal application of nitrogen fertilizer;N2,one third of base nitrogen fertilizer+two thirds of jointing stage supplemental nitrogen fertilizer)on maize root growth,photosynthetic characteristics,nitrogen use efficiency,and yield.The results demonstrated that SW impeded root growth and precipitated the premature aging of maize leaves following anthesis,particularly in the HT,which led to a notable reduction in maize yield.In comparison to N1,SN has been shown to increase root length density by 8.54%,root bleeding rate by 8.57%,and enhance root distribution ratio in the middle soil layers(20-60 cm).The interaction between SW and SN had a notable impact on maize growth and yield.The SN improved the absorption and utilization efficiency of nitrogen by promoting root development and downward canopy growth,thus improving the tolerance of maize to SW at the later stage of growth.In particular,the N2HT resulted in a 14.51%increase in the photosynthetic rate,a 18.58%increase in nitrogen absorption efficiency,and a 18.32%increase in maize yield compared with N1HT.It can be posited that the SN represents a viable nitrogen management measure with the potential to enhance maize tolerance to soil high-temperature stress.
基金Financial support from National Basic Research Program of China （973 Program） （No. 2015CB856600）, the National Natural Science Foundation of China （Nos. 21325206, 21632001）, National Young Top-notch Talent Support Program, CAS Interdisciplinary Innovation Team, and Peking University Health Science Center （Nos. BMU20150505, BMU20160541） is greatly ap- preciated. We thank Bencong Zhu and Ao Sun in this group for reproducing the results of 2a and 2k.
文摘An efficient KI catalyzed nitrogenation of aldehydes and alcohols for the direct synthesis of carbamoyl azides and ureas via a radical process has been developed. The simple operating procedures, the readily available starting materials including aldehydes, alcohols and amines, as well as the utility of the products all make this strategy very attractive.
基金supported by the National Natural Science Foundation of China(51609247)the Henan Provincial Natural Science Foundation,China(222300420589,202300410553)+4 种基金the Central Public-interest Scientific Institution Basal Research Fund,China(FIRI2022-22)the Science&Technology Fundamental Resources Investigation Program,China(2022FY101601)the Science and Technology Project of Xinxiang City,Henan Province,China(GG2021024)the Major Special Science and Technology Project of Henan Province,China(221100110700)the Joint Fund of Science and Technology Research and Development Plan of Henan Province,China(Superior Discipline Cultivation)(222301420104)。
文摘Nitrogen(N)uptake is regulated by water availability,and a water deficit can limit crop N responses by reducing N uptake and utilization.The complex and multifaceted interplay between water availability and the crop N response makes it difficult to predict and quantify the effect of water deficit on crop N status.The nitrogen nutrition index(NNI)has been widely used to accurately diagnose crop N status and to evaluate the effectiveness of N application.The decline of NNI under water-limiting conditions has been documented,although the underlying mechanism governing this decline is not fully understood.This study aimed to elucidate the reason for the decline of NNI under waterlimiting conditions and to provide insights into the accurate utilization of NNI for assessing crop N status under different water-N interaction treatments.Rainout shelter experiments were conducted over three growing seasons from 2018 to 2021 under different N(75 and 225 kg N ha^(-1),low N and high N)and water(120 to 510 mm,W0 to W3)co-limitation treatments.Plant N accumulation,shoot biomass(SB),plant N concentration(%N),soil nitrate-N content,actual evapotranspiration(ET_a),and yield were recorded at the stem elongation,booting,anthesis and grain filling stages.Compared to W0,W1 to W3 treatments exhibited NNI values that were greater by 10.2 to 20.5%,12.6to 24.8%,14 to 24.8%,and 16.8 to 24.8%at stem elongation,booting,anthesis,and grain filling,respectively,across the 2018-2021 seasons.This decline in NNI under water-limiting conditions stemmed from two main factors.First,reduced ET_(a) and SB led to a greater critical N concentration(%N_(c))under water-limiting conditions,which contributed to the decline in NNI primarily under high N conditions.Second,changes in plant%N played a more significant role under low N conditions.Plant N accumulation exhibited a positive allometric relationship with SB and a negative relationship with soil nitrate-N content under water-limiting conditions,indicating co-regulation by SB and the soil nitrate-N content.However,this regulation was influenced by water availability.Plant N accumulation sourced from the soil nitrate-N content reflects soil N availability.Greater soil water availability facilitated greater absorption of soil nitrate-N into the plants,leading to a positive correlation between plant N accumulation and ET_(a)across the different water-N interaction treatments.Therefore,considering the impact of soil water availability is crucial when assessing soil N availability under water-limiting conditions.The findings of this study provide valuable insights into the factors contributing to the decline in NNI among different water-N interaction treatments and can contribute to the more accurate utilization of NNI for assessing winter wheat N status.
基金the National Key R&D Program of China(grant no.2021YFA1501700)the NSFC(grant nos.22131002,22161142019,81821004),and the Tencent Foundation for financial support.
文摘Amides are among the fundamental chemicals in organic chemistry.Compared to other carbonyl functional groups,the transformation of amide is relatively difficult and remains a challenge.The traditional deconstruction transformations of amides to other functional products are usually limited to twisted or electronically activated amides.Herein,we describe a direct nitrogenation approach to convert amides into nitriles.This chemistry provides a novel amide transformation pathway via both C–C and C–N bond cleavage.Interestingly,the simple,readily available,and inexpensive inorganic salt NaNO2 is successfully employed as a nitrogen source in this organic N-incorporation process.Applications of this study are demonstrated through the latestage modification of drug and natural product derivatives.
基金supported by the Special Funds for Chengde national innovation demonstration area construction of science and technology special project sustainable development agenda(No.202104F001)the National Basic Research Program of China(No.2019YFC0408602).
文摘Nitrogen removal from domestic sewage is usually limited by insufficient carbon source and electron donor.An economical solid carbon source was developed by composition of polyvinyl alcohol,sodium alginate,and corncob,which was utilized as external carbon source in the anaerobic anoxic oxic(AAO)-biofilter for the treatment of low carbon-to-nitrogen ratio domestic sewage,and the nitrogen removal was remarkably improved from 63.2%to 96.5%.Furthermore,the effluent chemical oxygen demand maintained at 35 mg/L or even lower,and the total nitrogenwas reduced to less than 2mg/L.Metagenomic analysis demonstrated that the microbial communities responsible for potential denitrification and organic matter degradation in both AAO and the biofilter reactors were mainly composed of Proteobacteria and Bacteroides,respectively.The solid carbon source addition resulted in relatively high abundance of functional enzymes responsible for NO_(3)^(−)-N to NO_(2)^(−)-N con-version in both AAO and the biofilter reactors,thus enabled stable reaction.The carbon source addition during glycolysis primarily led to the increase of genes associated with the metabolic conversion of fructose 1.6P2 to glycerol-3P The reactor maintained high abun-dance of genes related to the tricarboxylic acid cycle,and then guaranteed efficient carbon metabolism.The results indicate that the composite carbon source is feasible for denitri-fication enhancement of AAO-biofilter,which contribute to the theoretical foundation for practical nitrogen removal application.
基金supported by the Key Research and Development Program of Shaanxi,China(2021NY-083)the National Natural Science Foundation of China(31871567)。
文摘The trade-off between yield and environmental effects caused by nitrogen fertilizer application is an important issue in wheat production.A reduction in fertile florets is one of the main reasons for the lower yields under low nitrogen application rates.Brassinosteroids(BRs)have been found to play a role in nitrogen-induced rice spikelet degeneration.However,whether BRs play a role in wheat floret development and the mechanisms involved are not clear.Therefore,a nitrogen gradient experiment and exogenous spraying experiment were conducted to investigate the role and mechanism of BRs in wheat floret development under low nitrogen stress.The results showed that as the nitrogen application decreased,the endogenous BRs content of the spikes decreased,photosynthesis weakened,and total carbon,soluble sugar and starch in the spikes decreased,leading to a reduction in the number of fertile florets.Under low nitrogen stress,exogenous spraying of 24-epibrassinolide promoted photosynthesis,and stimulated stem fructan hydrolysis and the utilization and storage of sucrose in spikes,which directed more carbohydrates to the spikes and increased the number of fertile florets.In conclusion,BRs mediate the effects of nitrogen fertilizer on wheat floret development,and under low nitrogen stress,foliar spraying of 24-epibrassinolide promotes the flow of carbohydrates from the stem to the spikes,alleviating wheat floret degeneration.
基金supported by the Key-Area Research and Development Program of Guangdong Province(Grant No.2021B0909060004)the National Natural Science Foundation of China(Grant Nos.12072355 and 92271117)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0620202).
文摘The thermochemical non-equilibrium phenomena encountered by hypersonic vehicles present significant challenges in their design.To investigate the thermochemical reaction flow behind shock waves,the non-equilibrium radiation in the visible range using a shock tube was studied.Experiments were conducted with a shock velocity of 4.7 km/s,using nitrogen at a pressure of 20 Pa.To address measurement difficulties associated with weak radiation,a special square section shock tube with a side length of 380 mm was utilized.A high-speed camera characterized the shock wave’s morphology,and a spectrograph and a monochromator captured the radiation.The spectra were analyzed,and the numerical spectra were compared with experimental results,showing a close match.Temperature changes behind the shock wave were obtained and compared with numerical predictions.The findings indicate that the vibrational temperatures are overestimated,while the vibrational relaxation time is likely underestimated,due to the oversimplified portrayals of the non-equilibrium relaxation process in the models.Additionally,both experimental and simulated time-resolved profiles of radiation intensity at specific wavelengths were analyzed.The gathered data aims to enhance computational fluid dynamics codes and radiation models,improving their predictive accuracy.
基金financially supported by the National Natural Science Foundation of China(No.21675131)the Volkswagen Foundation(Freigeist Fellowship No.89592)+1 种基金the Natural Science Foundation of Chongqing(No.2020jcyj-zdxmX0003,CSTB2023NSCQ-MSX0924)the National Research Foundation,Singapore,and A*STAR(Agency for Science Technology and Research)under its LCER Phase 2 Programme Hydrogen&Emerging Technologies FI,Directed Hydrogen Programme(Award No.U2305D4003).
文摘Ammonia and nitric acid,versatile industrial feedstocks,and burgeoning clean energy vectors hold immense promise for sustainable development.However,Haber–Bosch and Ostwald processes,which generates carbon dioxide as massive by-product,contribute to greenhouse effects and pose environmental challenges.Thus,the pursuit of nitrogen fixation through carbon–neutral pathways under benign conditions is a frontier of scientific topics,with the harnessing of solar energy emerging as an enticing and viable option.This review delves into the refinement strategies for scale-up mild photocatalytic nitrogen fixation,fields ripe with potential for innovation.The narrative is centered on enhancing the intrinsic capabilities of catalysts to surmount current efficiency barriers.Key focus areas include the in-depth exploration of fundamental mechanisms underpinning photocatalytic procedures,rational element selection,and functional planning,state-of-the-art experimental protocols for understanding photo-fixation processes,valid photocatalytic activity evaluation,and the rational design of catalysts.Furthermore,the review offers a suite of forward-looking recommendations aimed at propelling the advancement of mild nitrogen photo-fixation.It scrutinizes the existing challenges and prospects within this burgeoning domain,aspiring to equip researchers with insightful perspectives that can catalyze the evolution of cutting-edge nitrogen fixation methodologies and steer the development of next-generation photocatalytic systems.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Category B,XDB1090000).
文摘Plant synthetic biology has emerged as a transformative field in agriculture,offering innovative solutions to enhance food security,provide resilience to climate change,and transition to sustainable farming practices.By integrating advanced genetic tools,computational modeling,and systems biology,researchers can precisely modify plant genomes to enhance traits such as yield,stress tolerance,and nutrient use efficiency.The ability to design plants with specific characteristics tailored to diverse environmental conditions and agricultural needs holds great potential to address global food security challenges.Here,we highlight recent advancements and applications of plant synthetic biology in agriculture,focusing on key areas such as photosynthetic efficiency,nitrogen fixation,drought tolerance,pathogen resistance,nutrient use efficiency,biofortification,climate resilience,microbiology engineering,synthetic plant genomes,and the integration of artificial intelligence with synthetic biology.These innovations aim to maximize resource use efficiency,reduce reliance on external inputs,and mitigate environmental impacts associated with conventional agricultural practices.Despite challenges related to regulatory approval and public acceptance,the integration of synthetic biology in agriculture holds immense promise for creating more resilient and sustainable agricultural systems,contributing to global food security and environmental sustainability.Rigorous multi-field testing of these approaches will undoubtedly be required to ensure reproducibility.
基金supported by China Postdoctoral Science Foundation(2023M733220)Zhengzhou PM_(2.5)and O_(3)Collaborative Control and Monitoring Project(20220347A)the National Key Research and Development Program of China(No.2017YFC0212403).
文摘HONO is a critical precursor of•OH,but its sources are controversial due to its complex formation mechanism.This study conducted comprehensive observations in Zhengzhou from April 26 to May 11,2022.Low NO_(x)concentrations were observed during the Covid epidemic period(EP)(10.4±3.0 ppb),compared to the pre-epidemic period(PEP)(12.5±3.8 ppb).The mean HONO concentration during EP(0.53±0.34 ppb)was 0.09 ppb lower than that during PEP(0.62±0.53 ppb).The decrease in HONO concentration during EP came mainly at night due to the reduction in the direct emission(P_(emi))(0.03 ppb/hr),the homogeneous reaction between•OHandNO(P_(OH+NO))(0.02 ppb/hr),and the heterogeneous conversion of NO_(2)on the ground(0.01 ppb/hr).Notably,there was no significant change in daytime HONO concentration.The daytime HONO budget indicated that the primary HONO sources during PEP were the nitrate photolysis(P_(nitrate)),followed by the P_(OH+NO),Pemi,the photo-enhanced reaction of NO_(2)on the ground(P_(ground+hv))and aerosol surface(Paerosol+hv).The primary HONO sources were Pnitrate,POH+NO,P_(emi),and_(Paerosol+hv)during EP,respectively.The missing source has a high correlation with solar radiation,there might be other photo-related HONO sources or the contributions of photosensitized reactions were underestimated.In the extremely underestimated cases,HONO production rates fromthe P_(nitrate),P_(ground+hv),and Paerosol+hv increased by 0.17,0.10,and 0.10 ppb/hr during PEP,0.23,0.13,and 0.16 ppb/hr during EP,and P_(nitrate)was still the primary source during both PEP and EP.
基金supported by the Science and Technology Planning Project of Fujian Province(No.2023Y4015)the Marine and Fishery Development Special Fund of Xiamen(No.23YYST064QCB36)the Natural Science Foundation of Fujian Province(No.2021J011210).
文摘The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by depositing Pt and RuO_(2)particles onto g-C_(3)N_(4).The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and UV–vis diffuse reflectance spectrometer(UV–vis DRS).The photocatalysts were then applied to the removal of both NH_(4)^(+)-N and bacteria from simulated mariculture wastewater.The results clarified that the removals of both NH_(4)^(+)-N and bacteria were in the sequence of g-C_(3)N_(4)<RuO_(2)/g-C_(3)N_(4)<Pt/g-C_(3)N_(4)<Pt/RuO_(2)/g-C_(3)N_(4).This magnificent photocatalytic ability of Pt/RuO_(2)/g-C_(3)N_(4)can be interpreted by the transfer of holes from g-C_(3)N_(4)to RuO_(2)to facilitate the in situ generation of HClO from Cl^(−)in wastewater,while Pt extracts photogenerated electrons for H_(2)formation to enhance the reaction.The removal of NH_(4)^(+)-N and disinfection effect were more pronounced in simulated seawater than in purewater.The removal efficiency ofNH_(4)^(+)-N increases with an increase in pH of wastewater,while the bactericidal effect was more significant under a lower pH in a pH range of 6–9.In actual seawater aquaculture wastewater,Pt/RuO_(2)/g-C_(3)N_(4)still exhibits effective removal efficiency of NH_(4)^(+)-N and bactericidal performance under sunlight.This study provides an alternative avenue for removement of NH_(4)^(+)-N and bacteria from saline waters under sunlight.
基金supported by Natural Science Foundation of Shandong Province(Nos.ZR2022YQ42,ZR2021JQ15,ZR2021QE011,ZR2021ZD20,2022GJJLJRC-01)Innovative Team Project of Jinan(No.2021GXRC019)the National Natural Science Foundation of China(Nos.52022037,52202366).
文摘In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-depth exploration of photocatalytic reaction systems with fewer constraints imposed by surface chemistry.Typically,the isotropy of a specific facet provides a perfect support for studying heteroatom doping.Herein,this work delves into the intrinsic catalytic sites for photocatalytic nitrogen fixation in iron-doped lithium tantalate single crystals.The presence of iron not only modifies the electronic structure of lithium tantalate,improving its light absorption capacity,but also functions as an active site for the nitrogen adsorption and activation.The photocatalytic ammonia production rate of the iron-doped lithium tantalate in pure water is maximum 26.95μg cm^(−2)h^(−1),which is three times higher than that of undoped lithium tantalate.The combination of first-principles simulations with in situ characterizations confirms that iron doping promotes the rate-determining step and changes the pathway of hydrogenation to associative alternating.This study provides a new perspective on in-depth investigation of intrinsic catalytic active sites in photocatalysis and other catalytic processes.
基金funded by the Science and Technology Innovation Programof Jiangsu Province,China for“Carbon Dioxide Emission Peaking and Carbon Neutrality”(BE2022307).
文摘To promote the growth of cutting seeding of poplar(Populus L.),nitrogen(N)fertilizer and surface weed managements were required.We here conducted a pot experiment to examine the effects of natural vegetation,barnyardgrass(Echinochloa Beauv.),and sesbania(Sesbania cannabina pers.)on the growth of poplar cutting seedlings,soil properties,and ammonia(NH3)volatilization under three N inputs(0,0.5,and 1.5 g/pot,i.e.,N0,N0.5,and N1,respectively).Results showed that N application promoted the growth of poplar cutting seedlings,including plant height,ground diameter,and biomass,compared with N0 treatment.Moreover,under N0,sesbania significantly increased the plant height by 87.1%,barnyardgrass and sesbania significantly increased the ground diameter(16.2%and 51.5%),and biomass(67.4%and 74.7%)of poplar cutting seedlings,compared with natural vegetation management.Compared to natural vegetation,soil organic matter(SOM)of barnyardgrass and sesbania covered soil significantly increased by 12.4%and 18.7%at N1,respectively.In addition,soil total N(TN)content was significantly increased by 15.8%in barnyardgrass planted at N0.The soil ammonium N(NH_(4)^(+)-N)content decreased with the planting of barnyardgrass and sesbania across all levels of N application.At N0.5,the nitrate N(NO_(3)^(−)-N)content of soil planted with barnyardgrass significantly increased compared to both the natural vegetation and the sesbania groups.Compared to the natural vegetation,the soil available phosphorus(AP)content of the barnyardgrass group significantly increasing by 78.8%at N0.5,soil available potassium(AK)content was significantly reduced by 12.5%in the sesbania group at N0 and increased by 24.1%in the barnyardgrass group at N1.We found that cumulative NH3 emissions were significantly higher in all treatment groups at the N1 level than that at the N0.5 level,while the differences among the three plants treated were not significant.The results suggest that both barnyardgrass and sesbania promote seedling growth in the short term,while also increase certain properties.Therefore,effective herb management during the seedling stage is recommended in nurseries to support seedling growth and retain soil fertility.
基金supported by the National Key Research and Development Program of China(2022YFD190160304 and 2018YFD0301206)Natural Science Foundation of Sichuan Province(2022NSFSC0013)Sichuan Provincial Maize Innovation Team Construction Project(SCCXTD-2023-02).
文摘A four-year field experiment was conducted with two cultivars and four N rate to investigate the spatiotemporal characteristics of leaf senescence in maize after silking and its response to N fertilizer rates on them,as well as to reveal the differences in post-silking chlorophyll degradation between low-N-tolerant cultivars.The results showed that the order of leaf senescence after silking in maize was lower leaf>upper leaf>ear leaf,leaf tip>middle>base.Increasing N fertilizer down-regulated the expression of ZmCLH2 and ZmPPH in the leaves at 10-30 d after silking,reducing CLH and PPH activities,thereby delaying the leaf senescence.These effects were more prominent in low-N-sensitive cultivar Xianyu 508(XY508)than in low-N-tolerant cultivar Zhenghong 311(ZH311),especially in the lower leaves and leaf tip.Under low N condition,leaf yellowing and chlorophyll degradation occurred later and slower in ZH311 than in XY508.This resulted in a higher post-silking dry matter accumulation and grain yield in ZH311,which may be one of the important physiological bases of low nitrogen tolerant cultivars.Future research should focus on developing low-N-tolerant maize cultivars with slower leaf senescence near the ear after silking.
