In order to remove nitric oxides （NO） from flue gas, experimental studies on the photocatalytic oxidation （PCO） of NO are carried out in an efficient laboratory-scale reactor. Nano-sized TiO2 particles loading on ...In order to remove nitric oxides （NO） from flue gas, experimental studies on the photocatalytic oxidation （PCO） of NO are carried out in an efficient laboratory-scale reactor. Nano-sized TiO2 particles loading on quartz sand are prepared and used as the photocatalyst. Effects of several key operating parameters on NO conversion are investigated, including operating temperature, NO inlet concentration, oxygen percentage, relative humidity and residence time. The results illustrate that the NO inlet concentration, the oxygen percentage and the relative humidity play an important role in the oxidation of NO. A lower NO inlet concentration and a higher oxygen percentage result in a higher NO conversion efficiency. When the relative humidity is 8%, the maximum value of NO conversion efficiency is achieved. In addition, the operating temperature and the residence time have a little effect on the conversion efficiency of NO.展开更多
In this work,a new innovative absorption system containing both thiourea dioxide(TD)and FeⅡEDTA was used to NO removal.The independently influences of O2 volume concentration,TD concentration,original p H value and a...In this work,a new innovative absorption system containing both thiourea dioxide(TD)and FeⅡEDTA was used to NO removal.The independently influences of O2 volume concentration,TD concentration,original p H value and absorbent temperature on NO removal in bubbling device were examined preliminarily.The results revealed that the NO removal efficiency firstly increased and then decreased with the increasing of the three independent variables(O2 volume concentration,TD concentration and temperature).However,the NO removal efficiency monotonously increased to some extent with p H value increasing from 6.5 to 10.5.In addition,the respective effects of the four variables and the interactive function of them on NO removal were checked with the response surface methodology(RSM)by central composite design(CCD).The calculative model showed that pH value possessed a main positive independent impact on NO removal.Furthermore,the interactive effects between any two factors were expounded by the 3D surface and counter plots.Finally,the optimum absorption conditions for the maximum NO removal at 94.3%experimentally and 95.8%statistically were obtained in O2 volume content of 6.0%,TD concentration of 0.02 mol·L^-1,original p H value of 10.5 and absorption temperature of 42℃.展开更多
Nitrogen dioxide（NO2） is one of the most common and harmful air pollutants. To analyze the response of plants to NO2 stress, we investigated the morphological change, reactive oxygen species（ROS） production and an...Nitrogen dioxide（NO2） is one of the most common and harmful air pollutants. To analyze the response of plants to NO2 stress, we investigated the morphological change, reactive oxygen species（ROS） production and antioxidant enzyme activity in Arabidopsis thaliana（Col-0） exposed to 1.7, 4, 8.5, and 18.8 mg/m3NO2. The results indicate that NO2 exposure affected plant growth and chlorophyll（Chl） content, and increased oxygen free radical（O2-）production rate in Arabidopsis shoots. Furthermore, NO2 elevated the levels of lipid peroxidation and protein oxidation, accompanied by the induction of antioxidant enzyme activities and change of ascorbate（As A） and glutathione（GSH） contents. Following this, we mimicked nitric acid mist under experimental conditions, and confirmed the antioxidant mechanism of the plant to the stress. Our results imply that NO2 and its acid mist caused pollution risk to plant systems. During the process, increased ROS acted as a signal to induce a defense response, and antioxidant status played an important role in plant protection against NO2/nitric acid mist-caused oxidative damage.展开更多
Stored peanuts often need treatments to control microbial infections as well as insects to maintain postharvest quality. Nitric oxide (NO) is a recently discovered fumigant for postharvest pest control. NO fumigation ...Stored peanuts often need treatments to control microbial infections as well as insects to maintain postharvest quality. Nitric oxide (NO) is a recently discovered fumigant for postharvest pest control. NO fumigation must be conducted under ultralow oxygen condition to preserve NO and always contains NO<sub>2</sub> due to NO reaction with oxygen and NO<sub>2</sub> has antimicrobial property. Therefore, NO fumigation has potential to control both pests and pathogens. In this study, we evaluated antimicrobial effects of NO<sub>2</sub> fumigation on unpasteurized unshelled peanuts. Peanuts were fumigated with 0.3%, 1.0%, and 3.0% NO<sub>2</sub> for three days at 25<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">˚</span></span></span>C by injecting NO gas into glass jars to react with O<sub>2</sub> in the atmosphere. After fumigation, wash-off microbial samples were collected from intact peanut samples and, then, cracked open peanut samples with non-selective tryptic soy broth medium. The wash-off samples were then diluted with both the non-selective medium and a fungal-selective potato dextrose broth medium and were tested on GreenLight<span style="white-space:nowrap;"><sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">™</span></span></sup></span> rapid enumeration test based on oxygen depletion on culture medium. All three NO<sub>2</sub> fumigation treatments showed significant antibacterial and antifungal effects on intact peanuts as well as on cracked peanuts with complete inhibition with 3.0% NO<sub>2</sub>. Fumigation did not have obvious effects on appearance of skinned peanut kernels. These results suggested that NO<sub>2</sub> fumigation has potential to control microbes on stored products, and NO fumigation with the combination of NO and NO<sub>2</sub> has potential to control both insects and microbes on stored products.展开更多
The defect engineering in graphene plays a significant role for the application of gas sensors. In this work, we proposed an efficient method to prepare ultrasensitive gas sensors based on the porous reduced graphene ...The defect engineering in graphene plays a significant role for the application of gas sensors. In this work, we proposed an efficient method to prepare ultrasensitive gas sensors based on the porous reduced graphene oxide(PRGO). Photo-Fenton etching was carried out on GO nanosheets in a controlled manner to enrich their vacancy defects. The resulting porous graphene oxide(PGO) was then drop-coated on interdigital electrodes and hydrothermal reduced at 180 °C. Controllable reduction was achieved by varying the water amount. The gas sensor based on PRGO-5 min-6h exhibited superior sensing and selective performance toward nitrogen dioxide(NO2), with an exceptional high sensitivity up to 12 ppm-1.The theoretical limit of detection is down to 0.66 ppb. The excellent performance could be mainly attributed to the typical vacancy defects of PRGO. Some residue carboxylic groups on the edges could also facilitate the adsorption of polar molecules. The process has a great potential for scalable fabrication of high-performance NO2gas sensors.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
Over the last decades, nitric oxide(NO) has been definitively recognised as one of the key players involved in immunity and inflammation. NO generation was originally described in activated macrophages, which still re...Over the last decades, nitric oxide(NO) has been definitively recognised as one of the key players involved in immunity and inflammation. NO generation was originally described in activated macrophages, which still represent the prototype of NO-producing cells. Notwithstanding, additional cell subsets belonging to both innate and adaptive immunity have been documented to sustain NO propagation by means of the enzymatic activity of different nitric oxide synthase isoforms. Furthermore, due to its chemical characteristics, NO could rapidly react with other free radicals to generate different reactive nitrogen species(RNS), which have been intriguingly associated with many pathological conditions. Nonetheless, the plethora of NO/RNS-mediated effects still remains extremely puzzling. The aim of this manuscript is to dig into the broad literature on the topic to provide intriguing insights on NO-mediated circuits within immune system. We analysed NO and RNS immunological clues arising from their biochemical properties, immunomodulatory activities and finally dealing with their impact on different pathological scenarios with far prompting intriguing perspectives for their pharmacological targeting.展开更多
The inherent stability and durability of polystyrene(PS)make it a valuable material but also complicate its chemical recycling.Oxidative degradation via hydrogen atom transfer(HAT)is a promising route for PS recovery,...The inherent stability and durability of polystyrene(PS)make it a valuable material but also complicate its chemical recycling.Oxidative degradation via hydrogen atom transfer(HAT)is a promising route for PS recovery,yet existing methods suffer from insufficient selectivity toward target products.Herein,we demonstrate an efficient approach to selectively convert PS into benzoic acid(BA)with an impressive yield of 90%.The process uses nitrogen dioxide(NO_(2)),generated in situ from sodium nitrite and acetic acid,as the primary catalyst,with commercially available cobalt chloride(CoCl_(2))as a cocatalyst under mild conditions(180℃,2 bar(1 bar=101 kPa)O_(2)).Mechanistic studies revealed that NO_(2)simultaneously interacts with the Cα-H and Cβ-H bonds of the benzyl group via a HAT mechanism to form a dioxetane intermediate.This intermediate undergoes a ring-opening process,facilitating C-C bond cleavage and subsequent oxidation to BA.Furthermore,the demonstrated applicability of real-world PS waste underscores the potential of this process to advance PS recycling technologies,ultimately helping mitigate the environmental impact of plastic waste.展开更多
Nitrogen dioxide(NO_(2))is a representative toxicant in air pollution that mostly arises from the exhaust gas released by automobiles.It is related to various respiratory diseases such as pneumonia and sudden infant d...Nitrogen dioxide(NO_(2))is a representative toxicant in air pollution that mostly arises from the exhaust gas released by automobiles.It is related to various respiratory diseases such as pneumonia and sudden infant death syndrome.Additionally,because the toxicity of nitrogen dioxide is high in overpopulated areas(i.e.,a capital or metropolis),the development of simple,practical,and facile sensors is highly needed.This work presents a flexible and disposable paper-based NO_(2)sensor based on a reduced graphene oxide/chitosan(r GO/CS)composite.The synthesized r GO/CS composite can be easily flexed and deformed into various shapes,which are attributed to chitosan molecules that function as a dispersion and reduction agent and support material.In addition,this composite can be attached to paper owing to its adhesive property;hence it can be utilized in versatile applications in a disposable manner.By analyzing the conductive change of the r GO/CS composite when it reacts with NO_(2),we can detect nitrogen dioxide in a concentration range of 0–100 ppm with a detection limit of 1 ppm.Moreover,we performed NO_(2)detection in the exhaust gas released by automobiles using the r GO/CS composite for practical application.The results indicated that the r GO/CS composite has the potential to be used in feasible gas sensing as a facile and disposable sensor under various conditions.展开更多
Acid-induced reduction of nitrites(NO_(2)-)to nitric oxide(NO)at Cu/Fe centers is one of the key steps in the nitrogen cycle and serves as an essential path to NO generation.In this study,we report the acid-catalysed ...Acid-induced reduction of nitrites(NO_(2)-)to nitric oxide(NO)at Cu/Fe centers is one of the key steps in the nitrogen cycle and serves as an essential path to NO generation.In this study,we report the acid-catalysed conversion of NO_(2)-to NO at the Cu^(II)centers in Cu^(II)-nitrito complexes,[(Me_(2)BPMEN)Cu^(II)(NO_(2)-)]+(1)and[(H_(2)BPMEN)Cu^(II)(NO_(2)-)]+(2).Both the Cu^(II)-NO_(2)-complexes showed the formation of NO(g)along with H_(2)O_(2)when reacted with one equivalent acid(H6^(+))via the N-O bond homolysis of the presumed Cu^(II)-nitrous acid([Cu-ONOH]^(2+))intermediate.However,the H_(2)O_(2)amount decreased with time or an increase in H6^(+)and completely disappeared when H6^(+)was more than about two equivalents accompanied by the generation of H_(2)O.We detected the released NO(g)by using headspace gas chromatography/mass spectrometry;moreover,the NO(g)evolution was confirmed by the formation of a significant amount of{CoNO}^(8),[(12-TMC)Co(NO)]^(2+)up to(90±5%)in the above reactions.Mechanistic investigations using^(15)N-labeled-^(15)NO_(2)-and^(18)O-labeled-^(16)O^(14)N^(18)O-revealed that the N-atom in NO is derived from the^(18)ONO-ligand,which was further confirmed by the detection of^(15)NO and N^(18)O gas in headspace gas chromatography/mass spectrometry.We also monitored and characterized the formation of H_(2)O_(2)(one equivalent of H6^(+))and H_(2)O(two equivalents of H6^(+))and the results describe the rationale behind biological NO_(2)-reduction reactions generating NO along with H_(2)O.We observed more than 90%recovery of(1)after 10 catalytic cycles of NO(g)generation.展开更多
The catalytic transferred of small molecules into high-value chemical products in green methods are highly perused,and has obtained huge attention.In this field,great progress has been achieved during the past five ye...The catalytic transferred of small molecules into high-value chemical products in green methods are highly perused,and has obtained huge attention.In this field,great progress has been achieved during the past five years.Followed by the roadmap(Chinese Chemical Letters,2019,30,2089-2109)written by us before five years,we think that it should be updated to give more insights in this field.Thus,we write the present roadmap based on the fast changed background.In this roadmap,oxygen and carbon dioxide reduction reactions(including at high temperature),photocatalytic hydrogen generation and carbon dioxide reduction reactions,(photo)electrocatalytic reduction of O_(2)to H_(2)O_(2)and NH_(3)generated from N_(2) are discussed.The progress and challenges in above catalytic processes are given.We believe this manuscript will give the researchers more suggestions and help them to obtain useful information in this field.展开更多
Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy...Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. Results Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P<0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P<0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P<0.05-0.005), the value of LPO in the WOs was increased gradually (P<0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P<0.005-0.001), but LPO increased (P<0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients?alpha (6 items) was 0.8021, P<0.0001, and that the standardized item alpha was 0.9577, P<0.0001. Conclusion Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.展开更多
Minimizing soil ammonia（NH_3） and nitrous oxide（N_2O） emission factors（EFs） has significant implications in regional air quality and greenhouse gas（GHG） emissions besides nitrogen（N） nutrient loss.The aim of...Minimizing soil ammonia（NH_3） and nitrous oxide（N_2O） emission factors（EFs） has significant implications in regional air quality and greenhouse gas（GHG） emissions besides nitrogen（N） nutrient loss.The aim of this study was to investigate the impacts of different N fertilizer treatments of conventional urea,polymer-coated urea,ammonia sulfate,urease inhibitor（NBPT,N-（n-butyl） thiophosphoric triamide）-treated urea,and nitrification inhibitor（DCD,dicyandiamide）-treated urea on emissions of NH_3 and GHGs from subtropical wheat cultivation.A field study was established in a Cancienne silt loam soil.During growth season,NH_3 emission following N fertilization was characterized using active chamber method whereas GHG emissions of N_2O,carbon dioxide（CO_2）,and methane（CH_4） were by passive chamber method.The results showed that coated urea exhibited the largest reduction（49%） in the EF of NH_3-N followed by NBPT-treated urea（39%） and DCD-treated urea（24%） over conventional urea,whereas DCD-treated urea had the greatest suppression on N_2O-N（87%） followed by coated urea（76%） and NBPT-treated urea（69%）.Split fertilization of ammonium sulfate-urea significantly lowered both NH_3-N and N_2O-N EF values but split urea treatment had no impact over one-time application of urea.Both NBPT and DCD-treated urea treatments lowered CO_2-C flux but had no effect on CH_4-C flux.Overall,application of coated urea or urea with NPBT or DCD could be used as a mitigation strategy for reducing NH_3 and N_2O emissions in subtropical wheat production in Southern USA.展开更多
Alkaloids are natural, semisynthetic or synthetic organic compounds, normally polar with basic chemical properties and containing at least one nitrogen atom in a heterocyclic ring. Some synthetic or semisynthetic subs...Alkaloids are natural, semisynthetic or synthetic organic compounds, normally polar with basic chemical properties and containing at least one nitrogen atom in a heterocyclic ring. Some synthetic or semisynthetic substances resemble the alkaloid architecture. Trivalent nitrogen in these substances is normal;however, some natural and semisynthetic alkaloids have pentavalent nitrogen. The drug pholcodine is a derivative of morphine. Pholcodine has very little addiction- developing effect. It is a semisynthetic alkaloid that was first synthesized in 1950 by Chabrier et al. Pholcodine possesses antitussive (cough relief) properties similar to codeine, morphine and ethylmorphine. The drug was used in liquid formulations as Tuxi and Tuxi Forte, and it is in present use in Tuxidrin as liquid mixture and in tablet form. Pholcodine is an Active Pharmacological Ingredient (API) in tablets and liquid mixtures. Leiras International and Weifa in Norway manufacture medical forms with pholcodine. Several impurities in pholcodine were described by J. Roe in 1997 and by Denk et al. in 2000 and 2002. In addition, several degradation products may be formed in liquid formulations under storage. Some of these products are related not to the original production of pholcodine but rather to its oxidation under storage. The appearance of degradation products strongly depends on the storage temperature and pH of the liquid phase. Pholcodine-N-oxide and pholcodine-N,N’-dioxide are among the degradation (oxidation) products;pholcodine can also degrade to morphine. There is little information about the toxicity of the N-oxide and no information on the N,N’-di- oxide of pholcodine. In this study, the fact that morphine is generated during the storage of formulations containing pholcodine is presented. Another antitussive mixture under the name Cosylan was analyzed to examine the oxidation of ethylmorphine to ethylmorphine-N-oxide. Ethylmorphine is the API in Cosylan.展开更多
Objective:To examine the effects of hydroalcoholic extract and fractions of Hordeum vulgare Linn.(H.vulgare,Da Mai)on streptozotocin(STZ)-induced diabetic nephropathy in Sprague-Dawley rat models.Methods:The study inv...Objective:To examine the effects of hydroalcoholic extract and fractions of Hordeum vulgare Linn.(H.vulgare,Da Mai)on streptozotocin(STZ)-induced diabetic nephropathy in Sprague-Dawley rat models.Methods:The study involved preliminary phytochemical screening of extract and fractions,estimation of secondary metabolites,chromatographic studies using high performance liquid chromatography(HPLC),antioxidant potential using 1,1-diphenyl-2-picrylhydrazyl(DPPH),nitric oxide radical scavenging and reducing power methods along with the determination of potential against diabetic nephropathy in STZ-induced rat models.Results:The phytochemical evaluation of the hydroalcoholic extract of H.vulgare and fractions revealed the presence of various phytoconstituents such as alkaloids,saponins,tannins,flavonoids,and glycosides.The chromatographic analysis indicated the peak complementing marker compound epicatechin and significant antioxidant activity in the extract and aqueous fraction.STZ-induced rats showed abnormal levels of serum albumin,creatinine,total cholesterol,blood urea nitrogen(BUN),and triglycerides,and urine albumin and creatinine,which returned to normal after 8 weeks of treatment with hydroalcoholic extract(400 mg/kg)and aqueous fraction(50 mg/kg)of H.vulgare.Conclusion:Hydroalcoholic extract(400 mg/kg)and aqueous fraction(50 mg/kg)of H.vulgare have significant antioxidant potential and positive effects on diabetic nephropathy.The fractionation and optimization increase the concentration of polyphenols in aqueous extract,causing a decrease in the dose required for effects against diabetic nephropathy.展开更多
Traditional NH_(3) production based on the Haber–Bosch process is usually accompanied by high energy consumption and a large amount of carbon dioxide emission,which are not conducive to the realization of global carb...Traditional NH_(3) production based on the Haber–Bosch process is usually accompanied by high energy consumption and a large amount of carbon dioxide emission,which are not conducive to the realization of global carbon neutralization.Electrochemical N_(2) reduction is regarded as a clean strategy to deal with this problem.In this work,porous LiFe_(5)O_(8) nanoparticle–reduced graphene oxide (rGO) is proposed as an efficient electrocatalyst for artificial N_(2)-to-NH_(3) fixation with excellent selectivity under ambient conditions.Electrochemical tests in 0.1 M HCl show that such a hybrid achieves a high NH_(3) yield of 36.025 mg h^(-1) mg_(cat.)^(-1) and a high faradaic efficiency of 13.08% at −0.2 V vs.the reversible hydrogen electrode.Furthermore,it also exhibits structural stability.Theoretical calculations reveal that LiFe_(5)O_(8)–rGO can efficiently catalyze NH_(3) synthesis with a low energy barrier.展开更多
【目的】豆科植物与根瘤菌形成的共生根瘤系统是自然界最典型的互利共生体系之一,也是豆科作物高效利用生物固氮的核心机制。黄腐酸作为一种天然有机小分子活性物质,能够显著提高豆科植物的结瘤数量、固氮效率以及产量,但其具体作用机...【目的】豆科植物与根瘤菌形成的共生根瘤系统是自然界最典型的互利共生体系之一,也是豆科作物高效利用生物固氮的核心机制。黄腐酸作为一种天然有机小分子活性物质,能够显著提高豆科植物的结瘤数量、固氮效率以及产量,但其具体作用机制仍不清楚。本研究从氮代谢方面探讨黄腐酸促进大豆结瘤固氮的作用机制。【方法】大豆盆栽试验在双层杯中进行,上层塑料杯中加入蛭石作为栽培基质,下层玻璃杯中加入低氮营养液。大豆幼苗移栽后,在基质中接种根瘤菌,在营养液中分别加入0、300、500、1000 mg/L黄腐酸,作为CK、H300、H500、H1000处理。在大豆生长后不同时间,测定了幼苗生长和叶绿素含量,根瘤数以及根瘤中的豆血红蛋白含量。采用黄腐酸处理第16天和第25天对照(CK)与H500处理组的大豆根瘤样品进行转录组测序,并将质量控制后获得的数据读数(clean reads)与大豆基因组匹配,并通过GO(gene ontology)和KEGG(Kyoto encyclopedia of genes and genomes)进行功能注释和富集分析,鉴定出与氮代谢通路相关的差异基因(DEGs)。以500 mg/L黄腐酸处理为基础,设置加入NO抑制剂(cPTIO)处理,同样进行幼苗和根瘤相关指标测定,分析了大豆根部氮代谢途径中的关键产物和关键酶活性。【结果】与CK相比,在黄腐酸处理16和25天,H500处理大豆的单株根瘤数量分别增加了73.12%和46.51%,根瘤中豆血红蛋白含量分别提高了45.38%和25.50%,叶绿素含量在黄腐酸处理5、9和14天分别增加了45.36%、27.86%以及12.64%。H300处理单株根瘤数量与CK无显著差异,H1000处理抑制了大豆结瘤。与CK相比,H500处理第16和25天的根瘤样本中,共获得428、2406个DEGs,其中分别注释到15和27个氮代谢通路相关的差异基因(DEGs)。与HA相比,HA+cPTIO处理显著降低大豆幼苗生长、根系结瘤数量和叶绿素含量,降低了根系NO、硝态氮和游离氨基酸含量。与CK相比,黄腐酸刺激了硝酸还原酶(NR)的活性,抑制了谷氨酸脱氢酶(GDH)活性以及降低了游离氨基酸含量,加速了NO_(3)^(-)-N的还原,减少了硝态氮和亚硝态氮的含量。【结论】适宜的黄腐酸浓度可有效上调大豆根瘤中豆血红蛋白、硝酸还原酶、天冬酰胺合成酶(AS)等氮代谢相关酶基因的表达,下调GDH基因表达量,进而调控谷氨酰胺合成酶/谷氨酸合成酶(GS/GOGAT)循环系统,提高豆血红蛋白含量和硝酸还原酶活性,加速了NO的清除,减少了NO_(3)^(-)-N含量,增强了氨基酸的转运能力,进而提高了大豆植株生长和结瘤能力,提高了根瘤固氮效率。展开更多
基金The National High Technology Research Program of China (863 Program) (No. 2008AA05Z303)the Science and Technology Program of Jiangsu Province (No. BE2010184)the Environmental Protection Scientific Research Subject of Jiangsu Province (No.201031)
文摘In order to remove nitric oxides （NO） from flue gas, experimental studies on the photocatalytic oxidation （PCO） of NO are carried out in an efficient laboratory-scale reactor. Nano-sized TiO2 particles loading on quartz sand are prepared and used as the photocatalyst. Effects of several key operating parameters on NO conversion are investigated, including operating temperature, NO inlet concentration, oxygen percentage, relative humidity and residence time. The results illustrate that the NO inlet concentration, the oxygen percentage and the relative humidity play an important role in the oxidation of NO. A lower NO inlet concentration and a higher oxygen percentage result in a higher NO conversion efficiency. When the relative humidity is 8%, the maximum value of NO conversion efficiency is achieved. In addition, the operating temperature and the residence time have a little effect on the conversion efficiency of NO.
基金supported by National Natural Science Foundation of China(No.21808031)。
文摘In this work,a new innovative absorption system containing both thiourea dioxide(TD)and FeⅡEDTA was used to NO removal.The independently influences of O2 volume concentration,TD concentration,original p H value and absorbent temperature on NO removal in bubbling device were examined preliminarily.The results revealed that the NO removal efficiency firstly increased and then decreased with the increasing of the three independent variables(O2 volume concentration,TD concentration and temperature).However,the NO removal efficiency monotonously increased to some extent with p H value increasing from 6.5 to 10.5.In addition,the respective effects of the four variables and the interactive function of them on NO removal were checked with the response surface methodology(RSM)by central composite design(CCD).The calculative model showed that pH value possessed a main positive independent impact on NO removal.Furthermore,the interactive effects between any two factors were expounded by the 3D surface and counter plots.Finally,the optimum absorption conditions for the maximum NO removal at 94.3%experimentally and 95.8%statistically were obtained in O2 volume content of 6.0%,TD concentration of 0.02 mol·L^-1,original p H value of 10.5 and absorption temperature of 42℃.
基金supported by the National Natural Science Foundation of China (Nos.21477070, 21377076)the Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) (Nos.20121401110003, 20131401110005)+2 种基金the Project for Science and Technology Development of Shanxi Province (No.20120313009-2)the Research Project supported by the Shanxi Scholarship Council of China (No.2012-009)the Program for the Top Young and Middle aged Innovative Talents of Higher Learning Institutions of Shanxi (TYMIT, No.20120201)
文摘Nitrogen dioxide（NO2） is one of the most common and harmful air pollutants. To analyze the response of plants to NO2 stress, we investigated the morphological change, reactive oxygen species（ROS） production and antioxidant enzyme activity in Arabidopsis thaliana（Col-0） exposed to 1.7, 4, 8.5, and 18.8 mg/m3NO2. The results indicate that NO2 exposure affected plant growth and chlorophyll（Chl） content, and increased oxygen free radical（O2-）production rate in Arabidopsis shoots. Furthermore, NO2 elevated the levels of lipid peroxidation and protein oxidation, accompanied by the induction of antioxidant enzyme activities and change of ascorbate（As A） and glutathione（GSH） contents. Following this, we mimicked nitric acid mist under experimental conditions, and confirmed the antioxidant mechanism of the plant to the stress. Our results imply that NO2 and its acid mist caused pollution risk to plant systems. During the process, increased ROS acted as a signal to induce a defense response, and antioxidant status played an important role in plant protection against NO2/nitric acid mist-caused oxidative damage.
文摘Stored peanuts often need treatments to control microbial infections as well as insects to maintain postharvest quality. Nitric oxide (NO) is a recently discovered fumigant for postharvest pest control. NO fumigation must be conducted under ultralow oxygen condition to preserve NO and always contains NO<sub>2</sub> due to NO reaction with oxygen and NO<sub>2</sub> has antimicrobial property. Therefore, NO fumigation has potential to control both pests and pathogens. In this study, we evaluated antimicrobial effects of NO<sub>2</sub> fumigation on unpasteurized unshelled peanuts. Peanuts were fumigated with 0.3%, 1.0%, and 3.0% NO<sub>2</sub> for three days at 25<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">˚</span></span></span>C by injecting NO gas into glass jars to react with O<sub>2</sub> in the atmosphere. After fumigation, wash-off microbial samples were collected from intact peanut samples and, then, cracked open peanut samples with non-selective tryptic soy broth medium. The wash-off samples were then diluted with both the non-selective medium and a fungal-selective potato dextrose broth medium and were tested on GreenLight<span style="white-space:nowrap;"><sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">™</span></span></sup></span> rapid enumeration test based on oxygen depletion on culture medium. All three NO<sub>2</sub> fumigation treatments showed significant antibacterial and antifungal effects on intact peanuts as well as on cracked peanuts with complete inhibition with 3.0% NO<sub>2</sub>. Fumigation did not have obvious effects on appearance of skinned peanut kernels. These results suggested that NO<sub>2</sub> fumigation has potential to control microbes on stored products, and NO fumigation with the combination of NO and NO<sub>2</sub> has potential to control both insects and microbes on stored products.
基金financially supported by National Natural Science Foundation of China (No. 52073302)。
文摘The defect engineering in graphene plays a significant role for the application of gas sensors. In this work, we proposed an efficient method to prepare ultrasensitive gas sensors based on the porous reduced graphene oxide(PRGO). Photo-Fenton etching was carried out on GO nanosheets in a controlled manner to enrich their vacancy defects. The resulting porous graphene oxide(PGO) was then drop-coated on interdigital electrodes and hydrothermal reduced at 180 °C. Controllable reduction was achieved by varying the water amount. The gas sensor based on PRGO-5 min-6h exhibited superior sensing and selective performance toward nitrogen dioxide(NO2), with an exceptional high sensitivity up to 12 ppm-1.The theoretical limit of detection is down to 0.66 ppb. The excellent performance could be mainly attributed to the typical vacancy defects of PRGO. Some residue carboxylic groups on the edges could also facilitate the adsorption of polar molecules. The process has a great potential for scalable fabrication of high-performance NO2gas sensors.
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 Grant from the Italian Ministry of Health,BANDO GIOVANI RICERCATORI,No.2009-GR-2009-1558698Agnellini AHR was granted by Cariparo Fundation Fellowship
文摘Over the last decades, nitric oxide(NO) has been definitively recognised as one of the key players involved in immunity and inflammation. NO generation was originally described in activated macrophages, which still represent the prototype of NO-producing cells. Notwithstanding, additional cell subsets belonging to both innate and adaptive immunity have been documented to sustain NO propagation by means of the enzymatic activity of different nitric oxide synthase isoforms. Furthermore, due to its chemical characteristics, NO could rapidly react with other free radicals to generate different reactive nitrogen species(RNS), which have been intriguingly associated with many pathological conditions. Nonetheless, the plethora of NO/RNS-mediated effects still remains extremely puzzling. The aim of this manuscript is to dig into the broad literature on the topic to provide intriguing insights on NO-mediated circuits within immune system. We analysed NO and RNS immunological clues arising from their biochemical properties, immunomodulatory activities and finally dealing with their impact on different pathological scenarios with far prompting intriguing perspectives for their pharmacological targeting.
基金supported by the National Natural Science Foundation of China(22376183 and 22209146)the Key Research and Development Program of Zhejiang Province(2024C03112)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20230633)。
文摘The inherent stability and durability of polystyrene(PS)make it a valuable material but also complicate its chemical recycling.Oxidative degradation via hydrogen atom transfer(HAT)is a promising route for PS recovery,yet existing methods suffer from insufficient selectivity toward target products.Herein,we demonstrate an efficient approach to selectively convert PS into benzoic acid(BA)with an impressive yield of 90%.The process uses nitrogen dioxide(NO_(2)),generated in situ from sodium nitrite and acetic acid,as the primary catalyst,with commercially available cobalt chloride(CoCl_(2))as a cocatalyst under mild conditions(180℃,2 bar(1 bar=101 kPa)O_(2)).Mechanistic studies revealed that NO_(2)simultaneously interacts with the Cα-H and Cβ-H bonds of the benzyl group via a HAT mechanism to form a dioxetane intermediate.This intermediate undergoes a ring-opening process,facilitating C-C bond cleavage and subsequent oxidation to BA.Furthermore,the demonstrated applicability of real-world PS waste underscores the potential of this process to advance PS recycling technologies,ultimately helping mitigate the environmental impact of plastic waste.
基金supported by the National Research Foundation of Korea(NRF)under Grant Nos.NRF-2017M3A9F1031229,NRF2017R1E1A1A01075439,and NRF-2019R1C1C1005668The Korea Environment Industry&Technology Institute(KEITI)through its Ecological Imitation-based Environmental Pollution Management Technology Development Project+1 种基金funded by the Korea Ministry of Environment(MOE)(2019002800009)And Korea University(Grant No.K2111511)。
文摘Nitrogen dioxide(NO_(2))is a representative toxicant in air pollution that mostly arises from the exhaust gas released by automobiles.It is related to various respiratory diseases such as pneumonia and sudden infant death syndrome.Additionally,because the toxicity of nitrogen dioxide is high in overpopulated areas(i.e.,a capital or metropolis),the development of simple,practical,and facile sensors is highly needed.This work presents a flexible and disposable paper-based NO_(2)sensor based on a reduced graphene oxide/chitosan(r GO/CS)composite.The synthesized r GO/CS composite can be easily flexed and deformed into various shapes,which are attributed to chitosan molecules that function as a dispersion and reduction agent and support material.In addition,this composite can be attached to paper owing to its adhesive property;hence it can be utilized in versatile applications in a disposable manner.By analyzing the conductive change of the r GO/CS composite when it reacts with NO_(2),we can detect nitrogen dioxide in a concentration range of 0–100 ppm with a detection limit of 1 ppm.Moreover,we performed NO_(2)detection in the exhaust gas released by automobiles using the r GO/CS composite for practical application.The results indicated that the r GO/CS composite has the potential to be used in feasible gas sensing as a facile and disposable sensor under various conditions.
基金supported by Grants-in-Aid(CRG/2021/003371)from SERB-DST.P.B.Kulbir,thank IISER Tirupati for their fellowship.
文摘Acid-induced reduction of nitrites(NO_(2)-)to nitric oxide(NO)at Cu/Fe centers is one of the key steps in the nitrogen cycle and serves as an essential path to NO generation.In this study,we report the acid-catalysed conversion of NO_(2)-to NO at the Cu^(II)centers in Cu^(II)-nitrito complexes,[(Me_(2)BPMEN)Cu^(II)(NO_(2)-)]+(1)and[(H_(2)BPMEN)Cu^(II)(NO_(2)-)]+(2).Both the Cu^(II)-NO_(2)-complexes showed the formation of NO(g)along with H_(2)O_(2)when reacted with one equivalent acid(H6^(+))via the N-O bond homolysis of the presumed Cu^(II)-nitrous acid([Cu-ONOH]^(2+))intermediate.However,the H_(2)O_(2)amount decreased with time or an increase in H6^(+)and completely disappeared when H6^(+)was more than about two equivalents accompanied by the generation of H_(2)O.We detected the released NO(g)by using headspace gas chromatography/mass spectrometry;moreover,the NO(g)evolution was confirmed by the formation of a significant amount of{CoNO}^(8),[(12-TMC)Co(NO)]^(2+)up to(90±5%)in the above reactions.Mechanistic investigations using^(15)N-labeled-^(15)NO_(2)-and^(18)O-labeled-^(16)O^(14)N^(18)O-revealed that the N-atom in NO is derived from the^(18)ONO-ligand,which was further confirmed by the detection of^(15)NO and N^(18)O gas in headspace gas chromatography/mass spectrometry.We also monitored and characterized the formation of H_(2)O_(2)(one equivalent of H6^(+))and H_(2)O(two equivalents of H6^(+))and the results describe the rationale behind biological NO_(2)-reduction reactions generating NO along with H_(2)O.We observed more than 90%recovery of(1)after 10 catalytic cycles of NO(g)generation.
基金supported by the National Natural Science Foundation of China(Nos.22268003,22102095,52204320,U20A20246 and 12275199,U22A20418,22075196,21972110,52202208)National Key Research and Development Program of China(Nos.2023YFA1507903,2022YFB3803600,2022YFB4002501)+9 种基金SINOPEC(Beijing)Research Institute of Chemical Industry Co.,Ltd.(No.223239)the Fundamental Research Funds for the Central Universities(No.CCNU22JC017)the Postdoctoral Science Foundation of China(No.2021M692535)the Natural Science Foundation of Shaanxi Province(No.2022JQ-095)the Basic Research Project Foundation of Xi’an Jiaotong University(No.xzy012024012)the Youth Foundation of State Key Laboratory of Electrical Insulation and Power Equipment(No.EIPE2131)the Russian Science Foundation(No.22-13-00035)the Ministry of Science and Higher Education within the framework of a State Assignment of the Ioffe Institute,Russian Academy of Sciences(No.FFUG-2024-0036)Yunnan Fundamental Research Projects(No.202305AF150116)the Research Project Supported by Shanxi Scholarship Council of China(No.2022-050)。
文摘The catalytic transferred of small molecules into high-value chemical products in green methods are highly perused,and has obtained huge attention.In this field,great progress has been achieved during the past five years.Followed by the roadmap(Chinese Chemical Letters,2019,30,2089-2109)written by us before five years,we think that it should be updated to give more insights in this field.Thus,we write the present roadmap based on the fast changed background.In this roadmap,oxygen and carbon dioxide reduction reactions(including at high temperature),photocatalytic hydrogen generation and carbon dioxide reduction reactions,(photo)electrocatalytic reduction of O_(2)to H_(2)O_(2)and NH_(3)generated from N_(2) are discussed.The progress and challenges in above catalytic processes are given.We believe this manuscript will give the researchers more suggestions and help them to obtain useful information in this field.
文摘Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. Results Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P<0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P<0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P<0.05-0.005), the value of LPO in the WOs was increased gradually (P<0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P<0.005-0.001), but LPO increased (P<0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients?alpha (6 items) was 0.8021, P<0.0001, and that the standardized item alpha was 0.9577, P<0.0001. Conclusion Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.
基金supported,in part,by a scholarship from the China Scholarship Council(CSC)
文摘Minimizing soil ammonia（NH_3） and nitrous oxide（N_2O） emission factors（EFs） has significant implications in regional air quality and greenhouse gas（GHG） emissions besides nitrogen（N） nutrient loss.The aim of this study was to investigate the impacts of different N fertilizer treatments of conventional urea,polymer-coated urea,ammonia sulfate,urease inhibitor（NBPT,N-（n-butyl） thiophosphoric triamide）-treated urea,and nitrification inhibitor（DCD,dicyandiamide）-treated urea on emissions of NH_3 and GHGs from subtropical wheat cultivation.A field study was established in a Cancienne silt loam soil.During growth season,NH_3 emission following N fertilization was characterized using active chamber method whereas GHG emissions of N_2O,carbon dioxide（CO_2）,and methane（CH_4） were by passive chamber method.The results showed that coated urea exhibited the largest reduction（49%） in the EF of NH_3-N followed by NBPT-treated urea（39%） and DCD-treated urea（24%） over conventional urea,whereas DCD-treated urea had the greatest suppression on N_2O-N（87%） followed by coated urea（76%） and NBPT-treated urea（69%）.Split fertilization of ammonium sulfate-urea significantly lowered both NH_3-N and N_2O-N EF values but split urea treatment had no impact over one-time application of urea.Both NBPT and DCD-treated urea treatments lowered CO_2-C flux but had no effect on CH_4-C flux.Overall,application of coated urea or urea with NPBT or DCD could be used as a mitigation strategy for reducing NH_3 and N_2O emissions in subtropical wheat production in Southern USA.
文摘Alkaloids are natural, semisynthetic or synthetic organic compounds, normally polar with basic chemical properties and containing at least one nitrogen atom in a heterocyclic ring. Some synthetic or semisynthetic substances resemble the alkaloid architecture. Trivalent nitrogen in these substances is normal;however, some natural and semisynthetic alkaloids have pentavalent nitrogen. The drug pholcodine is a derivative of morphine. Pholcodine has very little addiction- developing effect. It is a semisynthetic alkaloid that was first synthesized in 1950 by Chabrier et al. Pholcodine possesses antitussive (cough relief) properties similar to codeine, morphine and ethylmorphine. The drug was used in liquid formulations as Tuxi and Tuxi Forte, and it is in present use in Tuxidrin as liquid mixture and in tablet form. Pholcodine is an Active Pharmacological Ingredient (API) in tablets and liquid mixtures. Leiras International and Weifa in Norway manufacture medical forms with pholcodine. Several impurities in pholcodine were described by J. Roe in 1997 and by Denk et al. in 2000 and 2002. In addition, several degradation products may be formed in liquid formulations under storage. Some of these products are related not to the original production of pholcodine but rather to its oxidation under storage. The appearance of degradation products strongly depends on the storage temperature and pH of the liquid phase. Pholcodine-N-oxide and pholcodine-N,N’-dioxide are among the degradation (oxidation) products;pholcodine can also degrade to morphine. There is little information about the toxicity of the N-oxide and no information on the N,N’-di- oxide of pholcodine. In this study, the fact that morphine is generated during the storage of formulations containing pholcodine is presented. Another antitussive mixture under the name Cosylan was analyzed to examine the oxidation of ethylmorphine to ethylmorphine-N-oxide. Ethylmorphine is the API in Cosylan.
基金supported by Rashtrsant Tukadoji Maharaj Memorial Fellowship from Rashtrasant Tukadoji Maharaj Nagpur University。
文摘Objective:To examine the effects of hydroalcoholic extract and fractions of Hordeum vulgare Linn.(H.vulgare,Da Mai)on streptozotocin(STZ)-induced diabetic nephropathy in Sprague-Dawley rat models.Methods:The study involved preliminary phytochemical screening of extract and fractions,estimation of secondary metabolites,chromatographic studies using high performance liquid chromatography(HPLC),antioxidant potential using 1,1-diphenyl-2-picrylhydrazyl(DPPH),nitric oxide radical scavenging and reducing power methods along with the determination of potential against diabetic nephropathy in STZ-induced rat models.Results:The phytochemical evaluation of the hydroalcoholic extract of H.vulgare and fractions revealed the presence of various phytoconstituents such as alkaloids,saponins,tannins,flavonoids,and glycosides.The chromatographic analysis indicated the peak complementing marker compound epicatechin and significant antioxidant activity in the extract and aqueous fraction.STZ-induced rats showed abnormal levels of serum albumin,creatinine,total cholesterol,blood urea nitrogen(BUN),and triglycerides,and urine albumin and creatinine,which returned to normal after 8 weeks of treatment with hydroalcoholic extract(400 mg/kg)and aqueous fraction(50 mg/kg)of H.vulgare.Conclusion:Hydroalcoholic extract(400 mg/kg)and aqueous fraction(50 mg/kg)of H.vulgare have significant antioxidant potential and positive effects on diabetic nephropathy.The fractionation and optimization increase the concentration of polyphenols in aqueous extract,causing a decrease in the dose required for effects against diabetic nephropathy.
基金supported by the National Natural Science Foundation of China(No.21575137).
文摘Traditional NH_(3) production based on the Haber–Bosch process is usually accompanied by high energy consumption and a large amount of carbon dioxide emission,which are not conducive to the realization of global carbon neutralization.Electrochemical N_(2) reduction is regarded as a clean strategy to deal with this problem.In this work,porous LiFe_(5)O_(8) nanoparticle–reduced graphene oxide (rGO) is proposed as an efficient electrocatalyst for artificial N_(2)-to-NH_(3) fixation with excellent selectivity under ambient conditions.Electrochemical tests in 0.1 M HCl show that such a hybrid achieves a high NH_(3) yield of 36.025 mg h^(-1) mg_(cat.)^(-1) and a high faradaic efficiency of 13.08% at −0.2 V vs.the reversible hydrogen electrode.Furthermore,it also exhibits structural stability.Theoretical calculations reveal that LiFe_(5)O_(8)–rGO can efficiently catalyze NH_(3) synthesis with a low energy barrier.
文摘【目的】豆科植物与根瘤菌形成的共生根瘤系统是自然界最典型的互利共生体系之一,也是豆科作物高效利用生物固氮的核心机制。黄腐酸作为一种天然有机小分子活性物质,能够显著提高豆科植物的结瘤数量、固氮效率以及产量,但其具体作用机制仍不清楚。本研究从氮代谢方面探讨黄腐酸促进大豆结瘤固氮的作用机制。【方法】大豆盆栽试验在双层杯中进行,上层塑料杯中加入蛭石作为栽培基质,下层玻璃杯中加入低氮营养液。大豆幼苗移栽后,在基质中接种根瘤菌,在营养液中分别加入0、300、500、1000 mg/L黄腐酸,作为CK、H300、H500、H1000处理。在大豆生长后不同时间,测定了幼苗生长和叶绿素含量,根瘤数以及根瘤中的豆血红蛋白含量。采用黄腐酸处理第16天和第25天对照(CK)与H500处理组的大豆根瘤样品进行转录组测序,并将质量控制后获得的数据读数(clean reads)与大豆基因组匹配,并通过GO(gene ontology)和KEGG(Kyoto encyclopedia of genes and genomes)进行功能注释和富集分析,鉴定出与氮代谢通路相关的差异基因(DEGs)。以500 mg/L黄腐酸处理为基础,设置加入NO抑制剂(cPTIO)处理,同样进行幼苗和根瘤相关指标测定,分析了大豆根部氮代谢途径中的关键产物和关键酶活性。【结果】与CK相比,在黄腐酸处理16和25天,H500处理大豆的单株根瘤数量分别增加了73.12%和46.51%,根瘤中豆血红蛋白含量分别提高了45.38%和25.50%,叶绿素含量在黄腐酸处理5、9和14天分别增加了45.36%、27.86%以及12.64%。H300处理单株根瘤数量与CK无显著差异,H1000处理抑制了大豆结瘤。与CK相比,H500处理第16和25天的根瘤样本中,共获得428、2406个DEGs,其中分别注释到15和27个氮代谢通路相关的差异基因(DEGs)。与HA相比,HA+cPTIO处理显著降低大豆幼苗生长、根系结瘤数量和叶绿素含量,降低了根系NO、硝态氮和游离氨基酸含量。与CK相比,黄腐酸刺激了硝酸还原酶(NR)的活性,抑制了谷氨酸脱氢酶(GDH)活性以及降低了游离氨基酸含量,加速了NO_(3)^(-)-N的还原,减少了硝态氮和亚硝态氮的含量。【结论】适宜的黄腐酸浓度可有效上调大豆根瘤中豆血红蛋白、硝酸还原酶、天冬酰胺合成酶(AS)等氮代谢相关酶基因的表达,下调GDH基因表达量,进而调控谷氨酰胺合成酶/谷氨酸合成酶(GS/GOGAT)循环系统,提高豆血红蛋白含量和硝酸还原酶活性,加速了NO的清除,减少了NO_(3)^(-)-N含量,增强了氨基酸的转运能力,进而提高了大豆植株生长和结瘤能力,提高了根瘤固氮效率。
