Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This ...Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)exposure.The results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)concentrations.Denitrifying microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 phyla.Further,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite reduction.Functional gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species.The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).展开更多
The authors regret<an error occurred regarding the spelling of the author’s name in the final published manuscript.The correct spelling is Jingtao Bi,but it was mistakenly published as Jingtai Bi.We hereby request...The authors regret<an error occurred regarding the spelling of the author’s name in the final published manuscript.The correct spelling is Jingtao Bi,but it was mistakenly published as Jingtai Bi.We hereby request to correct the name to Jingtao Bi as originally intended.>.The authors would like to apologize for any inconvenience caused.展开更多
Zirconia nanotube array films(ZNAF)prepared by anodic oxidation method were used as immobilization materials for acridine orange(AO),rhodamine B(RB)and AO-RB systems.A comparative study on their fluorescence emission ...Zirconia nanotube array films(ZNAF)prepared by anodic oxidation method were used as immobilization materials for acridine orange(AO),rhodamine B(RB)and AO-RB systems.A comparative study on their fluorescence emission intensity,fluorescence resonance energy transfer(FRET)and fluorescence detection of nitrite in aqueous solutions and on immobilization films with ZNAF as carriers was carried out.Results demonstrate that the solution pH values and immobilization on ZNAF have a great influence on the per-formance of these fluorescent molecules.Compared with aqueous solutions,the fluorescence emission in-tensity of AO and RB is considerably increased by immobilization,which is 8.0 and 4.2 times higher than the original,respectively.The energy transfer efficiency(E)of the AO-RB system increases from 40.9%to 84.8%by loading it on ZNAF.Moreover,after immobilization onto ZNAF,the fluorescence detection performance of nitrite is also significantly improved.The limit of detection decreases from 0.95 ng/mL to 0.22 ng/mL and the sensitivity increases from 939.18 to 15,031.68 mL/μg through loading AO onto ZNAF.展开更多
The electrochemical conversion of toxic nitrite(NO_(2)-)is a promising approach for the simultaneous removal of nitrogen contaminants and synthesis of ammonia(NH_(3)).In this study,we present the Er-doping-induced ele...The electrochemical conversion of toxic nitrite(NO_(2)-)is a promising approach for the simultaneous removal of nitrogen contaminants and synthesis of ammonia(NH_(3)).In this study,we present the Er-doping-induced electronic modulation of CoP integrated with nitrogen-doped carbon(CN)nanosheets supported on a titanium mesh(Er-CoP@NC/TM)for the electrocatalytic NO_(2)-reduction reaction(eNO_(2)-RR)for NH_(3)synthesis.The catalyst demonstrates a high Faraday efficiency of 97.08±2.22%and a high yield of 2087.60±17.10μmol h^(-1)cm^(-2)for NH_(3)production.Characterization and theoretical calculations revealed that Er-doping facilitated the electronic modulation of CoP in Er-CoP@NC/TM,which regulated the adsorption behaviors of intermediates and was the rate-limiting step for the eNO_(2)-RR,thereby enhancing the electrocatalytic performance.Quenching experiments and electron paramagnetic resonance tests suggest that both direct electrocatalytic reduction by active hydrogen and electron transfer are critical for the eNO_(2)-RR for NH_(3)synthesis.Furthermore,Er-CoP@NC/TM exhibited high performance across a wide range of NO_(2)-concentrations(0.05-0.1 mol L^(-1))and pH values(4-13).In addition,the catalyst demonstrated strong resistance to anions and a long cycle life in simulated wastewater environments.This study offers a powerful approach for the remediation of NO_(2)-wastewater and recovery of valuable inorganic compounds.展开更多
Ammonia(NH_(3))is a fundamental chemical in agriculture and an ideal hydrogen carrier.Consequently,NH_(3)synthesis strategies with high efficiency,energy conservation,environmental friendliness,and sustainability are ...Ammonia(NH_(3))is a fundamental chemical in agriculture and an ideal hydrogen carrier.Consequently,NH_(3)synthesis strategies with high efficiency,energy conservation,environmental friendliness,and sustainability are desired eminently.The nitrite(NO_(2)^(-))reduction reaction(NO_(2-)RR)to NH_(3)offers a feasibly low-energy consumption and continuable approach to replace industrial NH_(3)synthesis.Herein,polyethyleneimine(PEI)modified Au core Rh shell nanodendrites(Au@Rh-NDs)nanohybrid(Au@Rh-NDs/PEI)with branched structure is synthesized,which achieves the high NH_(3)yield(1.68 mg h^(-1)mg_(cat)^(-1))and Faradaic efficiency(FE)of 95.86%for NO_(2)^(-)-RR at-0.39 V potential in neutral electrolyte.Particularly,the introduction of PEI significantly enhances the electroactivity of Au@Rh-NDs at low concentration of 1 mM NaNO_(2),which originates from the enrichment function of PEI for NO_(2)^(-)-ion.In addition,the Au basement permits the sustainable solar power to expedite the NO_(2)^(-)-RR at Au@Rh-NDs/PEI owing to the localized surface plasmon resonance(LSPR)of the Au core substrate.This work may provide an admissible tactic to build excellent catalysts on account of organic molecule-mediated interfacial engineering in a variety of fields of catalysis and electrocatalysis.展开更多
To prevent bacterial growth and ensure food safety,common practice involves the use of nitrite and phosphate salts.Neverthe-less,elevated nitrite levels in the body can contribute to the development of stomach and eso...To prevent bacterial growth and ensure food safety,common practice involves the use of nitrite and phosphate salts.Neverthe-less,elevated nitrite levels in the body can contribute to the development of stomach and esophageal cancers,while excessive phosphate levels may increase the risk of kidney dysfunction and the onset of osteoporosis.Electrochemical sensing has emerged as a reliable tech-nique for detecting nitrites and phosphates.This study specifically focuses on the use of TiO_(2)-based sensing materials for such detection.The synthesis of nanoparticulate TiO_(2) and Ag-doped TiO_(2) was successfully achieved through a solution combustion technique.The com-position of the materials was examined using X-ray diffraction(XRD)and X-ray absorption near-edge structure(XANES)methods,re-vealing a predominant anatase composition.Doping resulted in particle refinement,contributing to an increased specific surface area and enhanced electron transfer efficiency,as indicated in the examination by electrochemical impedance spectroscopy(EIS).Cyclic voltam-metry(CV)assessed the electrochemical behavior,demonstrating that in nitrite detection,a significant oxidation reaction occurred at an applied voltage of approximately 1.372 V,while in phosphate detection,the main reduction peak occurred at a voltage close to-0.48 V.High sensitivity(2μA·μM^(-1)·mm^(-2) for sodium nitrite and 2.1μA·μM^(-1)·mm^(-2) for potassium phosphate)and low limits of detection(0.0052 mM for sodium nitrite and 0.0045 mM for potassium phosphate)were observed.Experimental results support the potential use of Ag-doped TiO_(2) as a sensing device for nitrites and phosphates.展开更多
Electrocatalytic reduction of nitrate pollutants to produce ammonia offers an effective approach to realizing the artificial nitrogen cycle and replacing the energyintensive Haber-Bosch process.Nitrite is an important...Electrocatalytic reduction of nitrate pollutants to produce ammonia offers an effective approach to realizing the artificial nitrogen cycle and replacing the energyintensive Haber-Bosch process.Nitrite is an important intermediate product in the reduction of nitrate to ammonia.Therefore,the mechanism of converting nitrite into ammonia warrants further investigation.Molecular cobalt catalysts are regarded as promising for nitrite reduction reactions(NO_(2)^(−)RR).However,designing and controlling the coordination environment of molecular catalysts is crucial for studying the mechanism of NO_(2)^(−)RR and catalyst design.Herein,we develop a molecular platform of cobalt porphyrin with three coordination microenvironments(Co-N_(3)X_(1),X=N,O,S).Electrochemical experiments demonstrate that cobalt porphyrin with O coordination(CoOTPP)exhibits the lowest onset potential and the highest activity for NO_(2)^(−)RR in ammonia production.Under neutral,nonbuffered conditions over a wide potential range(−1.0 to−1.5 V versus AgCl/Ag),the Faradaic efficiency of nearly 90%for ammonia was achieved and reached 94.5%at−1.4 V versus AgCl/Ag,with an ammonia yield of 6,498μgh^(−1)and a turnover number of 22,869 at−1.5V versus AgCl/Ag.In situ characterization and density functional theory calculations reveal that modulating the coordination environment alters the electron transfer mode of the cobalt active center and the charge redistribution caused by the break of the ligand field.Therefore,this results in enhanced electrochemical activity for NO_(2)^(−)RR in ammonia production.This study provides valuable guidance for designing adjustments to the coordination environment of molecular catalysts to enhance catalytic activity.展开更多
The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development ...The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development of efficient bifunctional electrocatalysts.Herein,we put forward a high-efficiency coelectrolysis system by coupling the nitrite reduction reaction(NO_(2)RR)and the glycerol oxidation reaction(GOR)over a novel heterogeneous β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl catalyst.Theβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl shows excellent bifunctional performance with high Faradaic efficiencies of formate(90.1%)and NH_(3)(91.9%)at cell voltage of 1.5 V,high yield rate of formate(89.6 mg h^(-1)cm^(-2))and NH_(3)(36.07 mg h^(-1)cm^(-2))at cell voltage of 1.9 V,and superior stability in an anion exchange membrane co-electrolyzer.The in-situ Raman result confirms the unique Co/Cu-based bimetallic synergistic sites of β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl towards superior GOR performance,while the operando Fourier transform infrared spectroscopy demonstrates the improved protonation kinetics of key intermediates and optimized water dissociation ability ofβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl for high NO_(2)RR activity.Our work illuminates alternative avenues to exploit the innovative and energy-saving technology for the co-production of high-added chemicals.展开更多
The nitrite(NO_(2)^(−))to ammonia(NH3)electroreduction reaction(NO_(2)^(−)RR)would be impeded by sluggish proton-coupled electron transfer kinetics and competitive hydrogen evolution reaction(HER).A key to improving t...The nitrite(NO_(2)^(−))to ammonia(NH3)electroreduction reaction(NO_(2)^(−)RR)would be impeded by sluggish proton-coupled electron transfer kinetics and competitive hydrogen evolution reaction(HER).A key to improving the NH_(3) selectivity is to facilitate adsorption and activation of NO_(2)^(−),which is generally undesirable in unitary species.In this work,an efficient NO_(2)^(−)RR catalyst is constructed by cooperating Pd with In2O3,in which NO_(2)^(−)could adsorb on interfacial dual-site through“Pd–N–O–In”linkage,leading to strengthened NO_(2)^(−)adsorption and easier N=O bond cleavage than that on unitary Pd or In2O3.Moreover,the Pd/In_(2)O_(3)composite exhibits moderate H^(*)adsorption,which may facilitate protonation kinetics while inhibiting competitive HER.As a result,it exhibits a fairly high NH_(3)yield rate of 622.76 mmol h^(−1)g^(−1)cat with a Faradaic efficiency(FE)of 95.72%,good selectivity of 91.96%,and cycling stability towards the NO_(2)^(−)RR,surpassing unitary In_(2)O_(3)and Pd/C electrocatalysts.Besides,computed results indicate that NH_(3)production on Pd/In_(2)O_(3)follows the deoxidation to hydrogenation pathway.This work highlights the significance of H^(*)and NO_(2)^(−)adsorption modulation and N=O activation in NO_(2)^(−)RR electrochemistry by creating synergy between a mediocre catalyst with an appropriate cooperator.展开更多
Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the...Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the conventional Haber–Bosch process that operates under harsh conditions,which consumes large quantities of fossil fuels and releases a large amount of carbon dioxide.As an alternative,electrosynthesis is a prospective method for producing NH_(3)under normal temperature and pressure conditions.Although electrocatalytic nitrogen reduction to ammonia has attracted considerable attentions,the low solubility of N_(2)and high N≡N cracking energy render the achievements of high NH_(3) yield rate and Faradaic efficiency difficult.Nitrate and nitrite(NO_(x)^(-))are common N-containing pollutants.Due to their high solubilities and low dissociation energy of N=O,NO_(x)^(-)−are ideal raw materials for NH_(3) production.Therefore,electrocatalytic NO_(x)^(-)−reduction to NH_(3)(eNO_(x)RR)is a prospective strategy to simultaneously realise environmental protection and NH_(3) synthesis.This review offers a comprehensive understanding of the thriving eNO_(x)RR under ambient conditions.At first,the popular theory and mechanism of eNO_(x)RR and a summary of the measurement system and evaluation criteria are introduced.Thereafter,various strategies for developing NO_(x)−reduction catalysts are systematically presented and discussed.Finally,the challenges and possible prospects of electrocatalytic NO_(x)^(-1) reduction are outlined to facilitate energy-saving and environmentally friendly large-scale synthesis of NH_(3) in the future.展开更多
Electrochemical nitrite reduction reaction(NO_(2)^(-)RR) is a potential sustainable route for regulating the nitrogen cycle and ambient ammonia(NH_(3)) synthesis.However,it remains a challenge to precisely regulate th...Electrochemical nitrite reduction reaction(NO_(2)^(-)RR) is a potential sustainable route for regulating the nitrogen cycle and ambient ammonia(NH_(3)) synthesis.However,it remains a challenge to precisely regulate the reaction pathways and inhibit competing reactions(e.g.hydrogenolysis) for efficient and selective NH_(3) production in an aqueous solution environment.Here,we utilize the Schottky barrier-induced surface electric field to construct high-density electron-deficient Pd nanoparticles by modulating the N content in the carbon carrier to promote the enrichment and immobilization of NO_(2)^(-)on the electrode surface,which ensures the ultimate selectivity for NH_(3).With these properties,Pd@N_(0.14)C with the highest N content achieved excellent catalytic performance for the reduction of NO_(2)^(-)to NH_(3) with the 100% Faraday efficiency at-0.5 and-0.6 V vs,reversible hydrogen electrode(RHE) for NH_(3) production,which was significantly better than Pd/C and Pd@N_(x)C samples with lower N content.This study opens new avenues for rational construction of efficient electrocatalysts for nitrite removal and NH_(3) electrosynthesis.展开更多
In this study,the environmentally friendly precursor,tartaric acid(TA),was employed for the generation of CO_(2)anion radical(CO_(2)^(·-))in an advanced UV/TA/Fe^(3+)system to reduce the hazardous NO_(2)^(-)-N in...In this study,the environmentally friendly precursor,tartaric acid(TA),was employed for the generation of CO_(2)anion radical(CO_(2)^(·-))in an advanced UV/TA/Fe^(3+)system to reduce the hazardous NO_(2)^(-)-N in wastewater.To optimize this process,various factors,including the dosage of Fe^(3+),TA,and p H,were systematically investigated for their impact on the reduction process.Under the conditions of 3 mmol/L Fe^(3+)dosage,10 mmol/L TA dosage,and a pH of 2.5,NO_(2)^(-)-N was effectively removed from the water within 60 min,selectively transformed into N_(2),with a remarkable N_(2)selectivity of 91.2%.In the optimal conditions,the NO_(2)^(-)-N reduction mechanism in the UV/TA/Fe^(3+)system and the critical role of CO_(2)^(·-)were illustrated.Finally,this study explored the reduction of real nitrified seawater using the UV/TA/Fe^(3+)system.The results demonstrated that the UV/TA/Fe^(3+)system could completely eliminate NO_(2)^(-)-N and achieve a N_(2)selectivity of up to 90%,with minimal interference from coexisting ions.This work holds promising implications for the environmentally benign treatment of nitrite-polluted wastewater.展开更多
A highly efficient and concise bromocyclization has been successfully achieved,in which tryptamine/tryptophol derivates can be transformed to valuable HPI/TFI scaffolds with economic and green manners.Moreover,a contr...A highly efficient and concise bromocyclization has been successfully achieved,in which tryptamine/tryptophol derivates can be transformed to valuable HPI/TFI scaffolds with economic and green manners.Moreover,a controllable cascade transformation of bromocyclization and aromatic bromination has also been smoothly achieved to form dibrominated HPIs and TFIs.Production could be successfully scaled up under both the batch process and a continuous flow fashion.The most remarkable peculiarity of our process over all previous methods is that the generated water is the major waste.Notably,successful application of this new protocol has been demonstrated by the pharmaceutical and natural products syntheses.展开更多
Long-term excessive intake of nitrite(NO_(2)^(-))poses a great threat to human health,needing a simple and fast method to detect NO_(2)-in food.Herein,via a simple and feasible strategy,Mn/Yb/Er triple-doped CeO_(2) n...Long-term excessive intake of nitrite(NO_(2)^(-))poses a great threat to human health,needing a simple and fast method to detect NO_(2)-in food.Herein,via a simple and feasible strategy,Mn/Yb/Er triple-doped CeO_(2) nanozyme(Mn/Yb/Er/CeO_(2))was synthesized for highly sensitive ratiometric detection of nitrite.By doping Mn,Yb,Er into CeO_(2) lattice structure,Mn/Yb/Er/CeO_(2) nanozyme showed enhanced oxidase-like activity,obtaining a higher density of oxygen vacancy and a higher ratio of Ce^(3+)to Ce~(4+)than that of CeO_(2).The 3,3,5,5-tetramethylbenzidine(TMB)can be effectively oxidized by Mn/Yb/Er/CeO_(2) to produce the oxidized TMB(ox TMB),showing a significant absorption signal at 652 nm.Additionally,nitrite can react with ox TMB to produce yellow diazotized ox TMB,which is accompanied by an elevated absorption signal at 445 nm and a decreased absorption signal at 652 nm.Thus,based on the oxidase-mimetic activity of Mn/Yb/Er/CeO_(2) and the diazotization reaction between NO_(2)^(-)and ox TMB,a ratiometric colorimetric assay was established for NO_(2)^(-)detection in food.Furthermore,by integrating Mn/Yb/Er/CeO_(2) with a smartphone,a colorimetric smartphone-sensing platform was successfully fabricated for visualization and quantitative detection of NO_(2)^(-).Notably,this two-detection mode showed excellent sensitivity,selectivity,reliability and practicability in monitoring the NO_(2)^(-)in real samples,impling its great potential for food safety.展开更多
BACKGROUND The common cause of sodium nitrite poisoning has shifted from previous accidental intoxication by exposure or ingestion of contaminated water and food to recent alarming intentional intoxication as an emplo...BACKGROUND The common cause of sodium nitrite poisoning has shifted from previous accidental intoxication by exposure or ingestion of contaminated water and food to recent alarming intentional intoxication as an employed method of suicide/exit.The subsequent formation of methemoglobin(MetHb)restricts oxygen transport and utilization in the body,resulting in functional hypoxia at the tissue level.In clinical practice,a mismatch of cyanotic appearance and oxygen partial pressure usually contributes to the identification of methemoglobinemia.Prompt recognition of characteristic mismatch and accurate diagnosis of sodium nitrite poisoning are prerequisites for the implementation of standardized systemic interventions.CASE SUMMARY A pregnant woman was admitted to the Department of Critical Care Medicine at the First Affiliated Hospital of Harbin Medical University due to consciousness disorders and drowsiness 2 h before admission.Subsequently,she developed vomiting and cyanotic skin.The woman underwent orotracheal intubation,invasive mechanical ventilation(IMV),and correction of internal environment disturbance in the ICU.Her premature infant was born with a higher-than-normal MetHb level of 3.3%,and received detoxification with methylene blue and vitamin C,supplemental vitamin K1,an infusion of fresh frozen plasma,as well as respiratory support via orotracheal intubation and IMV.On day 3 after admission,the puerpera regained consciousness,evacuated the IMV,and resumed enteral nutrition.She was then transferred to the maternity ward 24 h later.On day 7 after admission,the woman recovered and was discharged without any sequelae.CONCLUSION MetHb can cross through the placental barrier.Level of MetHb both reflects severity of the sodium nitrite poisoning and serves as feedback on therapeutic effectiveness.展开更多
This study aimed to evaluate the quality of water from village boreholes by measuring physicochemical parameters such as nitrates, nitrites, and total organic carbon (TOC). Forty-five (45) village pumps from the South...This study aimed to evaluate the quality of water from village boreholes by measuring physicochemical parameters such as nitrates, nitrites, and total organic carbon (TOC). Forty-five (45) village pumps from the Southern (Basse Côte) and the Northern (Korhogo) region of Cte d’Ivoire (west Africa) were sampled. Physicochemical parameters such as temperature, pH, conductivity at 25˚C, and turbidity were determined in situ, while nitrite and nitrate were analyzed according to ISO 10304-1 (2007) standard and total organic carbon (TOC) by NF EN 1484 (1997) standard. The results showed that the borehole waters of the Basse Côte and Korhogo analyzed are acidic, with an average temperature of 27.51˚C ± 0.16˚C and 29.95˚C ± 0.51˚C respectively for the Basse Côte and Korhogo regions. The borehole waters of the Basse Côtedo not contain nitrites, while those of Korhogo have average nitrite contents of 0.32 mg/l. The average nitrate rate in the waters of the Basse Côte and Korhogo are 12.08 ± 2.11 mg/l and 11.03 ± 3.18 mg/l respectively. The average TOC concentration of the waters of the Basse Côte is 1.28 ± 0.32 mg/l and that of Korhogo is 0.56 ± 0.09 mg/L. The study showed that the borehole waters of the Basse Côte and Korhogo have average temperatures between 27.4˚C and 29.95˚C with a slightly acidic pH value and acceptable salinity. The TOC concentrations obtained at the different sampling points were all below the French standard (2 mg/L) except for certains pumps of the Basse Côte. The water samples from the Basse Côte were devoid of nitrite. On the other hand, those from Korhogo revealed the presence of nitrite. Also, the borehole waters of the regions of the Basse Côte and Korhogo contain relatively high nitrate contents, presumably due to anthropometric activity. Overall, our study on the quality of drinking water showed that the waters analyzed are in compliance with international standards and safe for consumption.展开更多
Food safety problems caused by excessive nitrite addition have been frequently reported and the detection of nitrite in food is particularly important. The standing time during the pretreatment of primary sample has a...Food safety problems caused by excessive nitrite addition have been frequently reported and the detection of nitrite in food is particularly important. The standing time during the pretreatment of primary sample has a great influence on the concentration of nitrite tested by spectrophotometric method. In this context, three kinds of food samples are prepared, including canned mustard, canned fish and home-made pickled water. A series of standing times are placed during the sample pretreatments and the corresponding nitrite contents in these samples are detected by spectrophotometric method based on N-ethylenediamine dihydrochloride. This study aims to find out a reasonable standing time during the pretreatment of food sample, providing influence factor for precise detection of nitrite.展开更多
The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments...The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments applying the sequencing batch reactor（SBR） activated sludge process to domestic wastewater with low C/N ratio. The addition of sodium chloride（NaCI） to influent was established to achieve nitrite build-up. The high nitrite accumulation, depending on the salinity in influent and the application duration of salt, was obtained in SBRs treating saline wastewater. The maintenance results indicated that the real-time SBRs can maintain stable nitrite accumulation, but conversion from shorter nitrification-denitrification to full nitrification-denitrification was observed after some operation cycles in the other SBR with fixed-time control. The presented method is valuable to offer a solution to realize and to maintain nitrogen removal via nitrite under normal conditions.展开更多
Two artificial intelligence techniques, artificial neural network and genetic algorithm, were applied to optimize the fermentation medium for improving the nitrite oxidization rate of nitrite oxidizing bacteria. Exper...Two artificial intelligence techniques, artificial neural network and genetic algorithm, were applied to optimize the fermentation medium for improving the nitrite oxidization rate of nitrite oxidizing bacteria. Experiments were conducted with the composition of medium components obtained by genetic algorithm, and the experimental data were used to build a BP (back propagation) neural network model. The concentrations of six medium components were used as input vectors, and the nitrite oxidization rate was used as output vector of the model. The BP neural network model was used as the objective function of genetic algorithm to find the optimum medium composition for the maximum nitrite oxidization rate. The maximum nitrite oxidization rate was 0.952 g 2 NO-2-N·(g MLSS)-1·d-1 , obtained at the genetic algorithm optimized concentration of medium components (g·L-1 ): NaCl 0.58, MgSO 4 ·7H 2 O 0.14, FeSO 4 ·7H 2 O 0.141, KH 2 PO 4 0.8485, NaNO 2 2.52, and NaHCO 3 3.613. Validation experiments suggest that the experimental results are consistent with the best result predicted by the model. A scale-up experiment shows that the nitrite degraded completely after 34 h when cultured in the optimum medium, which is 10 h less than that cultured in the initial medium.展开更多
The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end product was studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibi...The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end product was studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibited and very high levels of nitrite accumulation at different salinities were achieved under the conditions of 25—28℃, pH 7.5? ?.0 , and the influent ammonia nitrogen of 40—70 mg/L when seawater flow used to flush toilet was less than 35%(salinity 12393 mg/L, Cl - 6778 mg/L) of total domestic wastewater flow, which is mainly ascribed to much high chlorine concentration of seawater. Results showed that high seawater salinity is available for short-range nitrification to nitrite as the end product. When the seawater flow used to flush toilet accounting for above 70% of the total domestic wastewater flow, the removal efficiency of ammonia was still above 80% despite the removal of organics declined obviously(less than 60%). It was found that the effect of seawater salinity on the removal of organics was negative rather than positive one as shown for ammonia removal.展开更多
基金supported by the National Natural Science Foundation of China(No.41977029).
文摘Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)exposure.The results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)concentrations.Denitrifying microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 phyla.Further,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite reduction.Functional gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species.The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).
文摘The authors regret<an error occurred regarding the spelling of the author’s name in the final published manuscript.The correct spelling is Jingtao Bi,but it was mistakenly published as Jingtai Bi.We hereby request to correct the name to Jingtao Bi as originally intended.>.The authors would like to apologize for any inconvenience caused.
基金supported by the National Natural Science Foundation of China(No.51972095).
文摘Zirconia nanotube array films(ZNAF)prepared by anodic oxidation method were used as immobilization materials for acridine orange(AO),rhodamine B(RB)and AO-RB systems.A comparative study on their fluorescence emission intensity,fluorescence resonance energy transfer(FRET)and fluorescence detection of nitrite in aqueous solutions and on immobilization films with ZNAF as carriers was carried out.Results demonstrate that the solution pH values and immobilization on ZNAF have a great influence on the per-formance of these fluorescent molecules.Compared with aqueous solutions,the fluorescence emission in-tensity of AO and RB is considerably increased by immobilization,which is 8.0 and 4.2 times higher than the original,respectively.The energy transfer efficiency(E)of the AO-RB system increases from 40.9%to 84.8%by loading it on ZNAF.Moreover,after immobilization onto ZNAF,the fluorescence detection performance of nitrite is also significantly improved.The limit of detection decreases from 0.95 ng/mL to 0.22 ng/mL and the sensitivity increases from 939.18 to 15,031.68 mL/μg through loading AO onto ZNAF.
文摘The electrochemical conversion of toxic nitrite(NO_(2)-)is a promising approach for the simultaneous removal of nitrogen contaminants and synthesis of ammonia(NH_(3)).In this study,we present the Er-doping-induced electronic modulation of CoP integrated with nitrogen-doped carbon(CN)nanosheets supported on a titanium mesh(Er-CoP@NC/TM)for the electrocatalytic NO_(2)-reduction reaction(eNO_(2)-RR)for NH_(3)synthesis.The catalyst demonstrates a high Faraday efficiency of 97.08±2.22%and a high yield of 2087.60±17.10μmol h^(-1)cm^(-2)for NH_(3)production.Characterization and theoretical calculations revealed that Er-doping facilitated the electronic modulation of CoP in Er-CoP@NC/TM,which regulated the adsorption behaviors of intermediates and was the rate-limiting step for the eNO_(2)-RR,thereby enhancing the electrocatalytic performance.Quenching experiments and electron paramagnetic resonance tests suggest that both direct electrocatalytic reduction by active hydrogen and electron transfer are critical for the eNO_(2)-RR for NH_(3)synthesis.Furthermore,Er-CoP@NC/TM exhibited high performance across a wide range of NO_(2)-concentrations(0.05-0.1 mol L^(-1))and pH values(4-13).In addition,the catalyst demonstrated strong resistance to anions and a long cycle life in simulated wastewater environments.This study offers a powerful approach for the remediation of NO_(2)-wastewater and recovery of valuable inorganic compounds.
基金supported by the National Natural Science Foundation of China(22273056)the National Training Program of Innovation and Entrepreneurship for Undergraduates(202410718010)+2 种基金the Natural Science Basic Research Project of Shaanxi Province(2024JC-YBQN-0092)the Scientific research project of Shaanxi Institute of Basic Sciences(23JHQ003)the Scientific Research Program Funded by Education Department of Shaanxi Provincial Government(23JK0694)。
文摘Ammonia(NH_(3))is a fundamental chemical in agriculture and an ideal hydrogen carrier.Consequently,NH_(3)synthesis strategies with high efficiency,energy conservation,environmental friendliness,and sustainability are desired eminently.The nitrite(NO_(2)^(-))reduction reaction(NO_(2-)RR)to NH_(3)offers a feasibly low-energy consumption and continuable approach to replace industrial NH_(3)synthesis.Herein,polyethyleneimine(PEI)modified Au core Rh shell nanodendrites(Au@Rh-NDs)nanohybrid(Au@Rh-NDs/PEI)with branched structure is synthesized,which achieves the high NH_(3)yield(1.68 mg h^(-1)mg_(cat)^(-1))and Faradaic efficiency(FE)of 95.86%for NO_(2)^(-)-RR at-0.39 V potential in neutral electrolyte.Particularly,the introduction of PEI significantly enhances the electroactivity of Au@Rh-NDs at low concentration of 1 mM NaNO_(2),which originates from the enrichment function of PEI for NO_(2)^(-)-ion.In addition,the Au basement permits the sustainable solar power to expedite the NO_(2)^(-)-RR at Au@Rh-NDs/PEI owing to the localized surface plasmon resonance(LSPR)of the Au core substrate.This work may provide an admissible tactic to build excellent catalysts on account of organic molecule-mediated interfacial engineering in a variety of fields of catalysis and electrocatalysis.
基金Kasetsart University Research and Development Institute(KURDI,Grant No.FF(KU)51.67)ASEAN University Network/Southeast Asia Engineering Education Development Network(AUN/SEED-Net)for financial support+2 种基金financially supported by the Office of the Ministry of Higher Education,Science,Research and Innovationthe Thailand Science Research and Innovation through the Kasetsart University Reinventing University Program 2021support from the Department of Material Engineering,Faculty of Engineering,Kasetsart University is also acknowledged.
文摘To prevent bacterial growth and ensure food safety,common practice involves the use of nitrite and phosphate salts.Neverthe-less,elevated nitrite levels in the body can contribute to the development of stomach and esophageal cancers,while excessive phosphate levels may increase the risk of kidney dysfunction and the onset of osteoporosis.Electrochemical sensing has emerged as a reliable tech-nique for detecting nitrites and phosphates.This study specifically focuses on the use of TiO_(2)-based sensing materials for such detection.The synthesis of nanoparticulate TiO_(2) and Ag-doped TiO_(2) was successfully achieved through a solution combustion technique.The com-position of the materials was examined using X-ray diffraction(XRD)and X-ray absorption near-edge structure(XANES)methods,re-vealing a predominant anatase composition.Doping resulted in particle refinement,contributing to an increased specific surface area and enhanced electron transfer efficiency,as indicated in the examination by electrochemical impedance spectroscopy(EIS).Cyclic voltam-metry(CV)assessed the electrochemical behavior,demonstrating that in nitrite detection,a significant oxidation reaction occurred at an applied voltage of approximately 1.372 V,while in phosphate detection,the main reduction peak occurred at a voltage close to-0.48 V.High sensitivity(2μA·μM^(-1)·mm^(-2) for sodium nitrite and 2.1μA·μM^(-1)·mm^(-2) for potassium phosphate)and low limits of detection(0.0052 mM for sodium nitrite and 0.0045 mM for potassium phosphate)were observed.Experimental results support the potential use of Ag-doped TiO_(2) as a sensing device for nitrites and phosphates.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFC2105800National Natural Science Foundation of China,Grant/Award Numbers:21901084,21905106,22279041+2 种基金Higher Education Discipline Innovation Project,Grant/Award Number:B17020Specific Research Fund of the Innovation Platform for Academicians of Hainan Province,China,Grant/Award Number:YSPTZX202321Natural Science Foundation of Jilin Province,Grant/Award Number:SKL202302017.
文摘Electrocatalytic reduction of nitrate pollutants to produce ammonia offers an effective approach to realizing the artificial nitrogen cycle and replacing the energyintensive Haber-Bosch process.Nitrite is an important intermediate product in the reduction of nitrate to ammonia.Therefore,the mechanism of converting nitrite into ammonia warrants further investigation.Molecular cobalt catalysts are regarded as promising for nitrite reduction reactions(NO_(2)^(−)RR).However,designing and controlling the coordination environment of molecular catalysts is crucial for studying the mechanism of NO_(2)^(−)RR and catalyst design.Herein,we develop a molecular platform of cobalt porphyrin with three coordination microenvironments(Co-N_(3)X_(1),X=N,O,S).Electrochemical experiments demonstrate that cobalt porphyrin with O coordination(CoOTPP)exhibits the lowest onset potential and the highest activity for NO_(2)^(−)RR in ammonia production.Under neutral,nonbuffered conditions over a wide potential range(−1.0 to−1.5 V versus AgCl/Ag),the Faradaic efficiency of nearly 90%for ammonia was achieved and reached 94.5%at−1.4 V versus AgCl/Ag,with an ammonia yield of 6,498μgh^(−1)and a turnover number of 22,869 at−1.5V versus AgCl/Ag.In situ characterization and density functional theory calculations reveal that modulating the coordination environment alters the electron transfer mode of the cobalt active center and the charge redistribution caused by the break of the ligand field.Therefore,this results in enhanced electrochemical activity for NO_(2)^(−)RR in ammonia production.This study provides valuable guidance for designing adjustments to the coordination environment of molecular catalysts to enhance catalytic activity.
基金financially supported by the National Natural Science Foundation of China(22205205)the Science Foundation of Zhejiang Sci-Tech University(ZSTU)under Grant No.21062337-Y。
文摘The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development of efficient bifunctional electrocatalysts.Herein,we put forward a high-efficiency coelectrolysis system by coupling the nitrite reduction reaction(NO_(2)RR)and the glycerol oxidation reaction(GOR)over a novel heterogeneous β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl catalyst.Theβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl shows excellent bifunctional performance with high Faradaic efficiencies of formate(90.1%)and NH_(3)(91.9%)at cell voltage of 1.5 V,high yield rate of formate(89.6 mg h^(-1)cm^(-2))and NH_(3)(36.07 mg h^(-1)cm^(-2))at cell voltage of 1.9 V,and superior stability in an anion exchange membrane co-electrolyzer.The in-situ Raman result confirms the unique Co/Cu-based bimetallic synergistic sites of β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl towards superior GOR performance,while the operando Fourier transform infrared spectroscopy demonstrates the improved protonation kinetics of key intermediates and optimized water dissociation ability ofβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl for high NO_(2)RR activity.Our work illuminates alternative avenues to exploit the innovative and energy-saving technology for the co-production of high-added chemicals.
基金supported by the National Key R&D Program of China(Nos.2022YFA1503104 and 2022YFA1503102)the Natural Science Foundation of Shandong Province(No.2022HWYQ-009)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK20230243)Taishan Scholars Project(No.tspd20230601)Qilu Young Scholars Program of Shandong University.
文摘The nitrite(NO_(2)^(−))to ammonia(NH3)electroreduction reaction(NO_(2)^(−)RR)would be impeded by sluggish proton-coupled electron transfer kinetics and competitive hydrogen evolution reaction(HER).A key to improving the NH_(3) selectivity is to facilitate adsorption and activation of NO_(2)^(−),which is generally undesirable in unitary species.In this work,an efficient NO_(2)^(−)RR catalyst is constructed by cooperating Pd with In2O3,in which NO_(2)^(−)could adsorb on interfacial dual-site through“Pd–N–O–In”linkage,leading to strengthened NO_(2)^(−)adsorption and easier N=O bond cleavage than that on unitary Pd or In2O3.Moreover,the Pd/In_(2)O_(3)composite exhibits moderate H^(*)adsorption,which may facilitate protonation kinetics while inhibiting competitive HER.As a result,it exhibits a fairly high NH_(3)yield rate of 622.76 mmol h^(−1)g^(−1)cat with a Faradaic efficiency(FE)of 95.72%,good selectivity of 91.96%,and cycling stability towards the NO_(2)^(−)RR,surpassing unitary In_(2)O_(3)and Pd/C electrocatalysts.Besides,computed results indicate that NH_(3)production on Pd/In_(2)O_(3)follows the deoxidation to hydrogenation pathway.This work highlights the significance of H^(*)and NO_(2)^(−)adsorption modulation and N=O activation in NO_(2)^(−)RR electrochemistry by creating synergy between a mediocre catalyst with an appropriate cooperator.
基金supported by the National Natural Science Foundation of China[Nos.U21A20332,52103226,52202275,52203314,and 12204253]the Distinguished Young Scholars Fund of Jiangsu Province[No.BK20220061]the Fellowship of China Postdoctoral Science Foundation[No.2021M702382]。
文摘Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the conventional Haber–Bosch process that operates under harsh conditions,which consumes large quantities of fossil fuels and releases a large amount of carbon dioxide.As an alternative,electrosynthesis is a prospective method for producing NH_(3)under normal temperature and pressure conditions.Although electrocatalytic nitrogen reduction to ammonia has attracted considerable attentions,the low solubility of N_(2)and high N≡N cracking energy render the achievements of high NH_(3) yield rate and Faradaic efficiency difficult.Nitrate and nitrite(NO_(x)^(-))are common N-containing pollutants.Due to their high solubilities and low dissociation energy of N=O,NO_(x)^(-)−are ideal raw materials for NH_(3) production.Therefore,electrocatalytic NO_(x)^(-)−reduction to NH_(3)(eNO_(x)RR)is a prospective strategy to simultaneously realise environmental protection and NH_(3) synthesis.This review offers a comprehensive understanding of the thriving eNO_(x)RR under ambient conditions.At first,the popular theory and mechanism of eNO_(x)RR and a summary of the measurement system and evaluation criteria are introduced.Thereafter,various strategies for developing NO_(x)−reduction catalysts are systematically presented and discussed.Finally,the challenges and possible prospects of electrocatalytic NO_(x)^(-1) reduction are outlined to facilitate energy-saving and environmentally friendly large-scale synthesis of NH_(3) in the future.
文摘Electrochemical nitrite reduction reaction(NO_(2)^(-)RR) is a potential sustainable route for regulating the nitrogen cycle and ambient ammonia(NH_(3)) synthesis.However,it remains a challenge to precisely regulate the reaction pathways and inhibit competing reactions(e.g.hydrogenolysis) for efficient and selective NH_(3) production in an aqueous solution environment.Here,we utilize the Schottky barrier-induced surface electric field to construct high-density electron-deficient Pd nanoparticles by modulating the N content in the carbon carrier to promote the enrichment and immobilization of NO_(2)^(-)on the electrode surface,which ensures the ultimate selectivity for NH_(3).With these properties,Pd@N_(0.14)C with the highest N content achieved excellent catalytic performance for the reduction of NO_(2)^(-)to NH_(3) with the 100% Faraday efficiency at-0.5 and-0.6 V vs,reversible hydrogen electrode(RHE) for NH_(3) production,which was significantly better than Pd/C and Pd@N_(x)C samples with lower N content.This study opens new avenues for rational construction of efficient electrocatalysts for nitrite removal and NH_(3) electrosynthesis.
基金financially supported by National Natural Science Foundation of China(No.22208081)Central Guidance on Local Science and Technology Development Fund of Hebei Province(No.226Z3102G)Fundamental Research Funds of Hebei University of Technology(No.JBKYTD2001)。
文摘In this study,the environmentally friendly precursor,tartaric acid(TA),was employed for the generation of CO_(2)anion radical(CO_(2)^(·-))in an advanced UV/TA/Fe^(3+)system to reduce the hazardous NO_(2)^(-)-N in wastewater.To optimize this process,various factors,including the dosage of Fe^(3+),TA,and p H,were systematically investigated for their impact on the reduction process.Under the conditions of 3 mmol/L Fe^(3+)dosage,10 mmol/L TA dosage,and a pH of 2.5,NO_(2)^(-)-N was effectively removed from the water within 60 min,selectively transformed into N_(2),with a remarkable N_(2)selectivity of 91.2%.In the optimal conditions,the NO_(2)^(-)-N reduction mechanism in the UV/TA/Fe^(3+)system and the critical role of CO_(2)^(·-)were illustrated.Finally,this study explored the reduction of real nitrified seawater using the UV/TA/Fe^(3+)system.The results demonstrated that the UV/TA/Fe^(3+)system could completely eliminate NO_(2)^(-)-N and achieve a N_(2)selectivity of up to 90%,with minimal interference from coexisting ions.This work holds promising implications for the environmentally benign treatment of nitrite-polluted wastewater.
基金supported by the National Natural Science Foundation of China(No.22208302)the Natural Science Foundation of Zhejiang Province of China(Nos.LQ21B020006,ZJ2022039)。
文摘A highly efficient and concise bromocyclization has been successfully achieved,in which tryptamine/tryptophol derivates can be transformed to valuable HPI/TFI scaffolds with economic and green manners.Moreover,a controllable cascade transformation of bromocyclization and aromatic bromination has also been smoothly achieved to form dibrominated HPIs and TFIs.Production could be successfully scaled up under both the batch process and a continuous flow fashion.The most remarkable peculiarity of our process over all previous methods is that the generated water is the major waste.Notably,successful application of this new protocol has been demonstrated by the pharmaceutical and natural products syntheses.
基金supported by the National Natural Science Foundation of China(Nos.22004111 and 21974125)the Tackle Key Problems in Science and Technology Project of Henan Province,China(No.222102310386)+3 种基金China Postdoctoral Science Foundation(No.2020M682327)Henan Postdoctoral Foundation(No.202002009)Program for Innovative Research Team(in Science and Technology)in University of Henan Province(No.22TRTSTHN002)Excellent Youth Foundation of Henan Scientific Committee(No.232300421021)。
文摘Long-term excessive intake of nitrite(NO_(2)^(-))poses a great threat to human health,needing a simple and fast method to detect NO_(2)-in food.Herein,via a simple and feasible strategy,Mn/Yb/Er triple-doped CeO_(2) nanozyme(Mn/Yb/Er/CeO_(2))was synthesized for highly sensitive ratiometric detection of nitrite.By doping Mn,Yb,Er into CeO_(2) lattice structure,Mn/Yb/Er/CeO_(2) nanozyme showed enhanced oxidase-like activity,obtaining a higher density of oxygen vacancy and a higher ratio of Ce^(3+)to Ce~(4+)than that of CeO_(2).The 3,3,5,5-tetramethylbenzidine(TMB)can be effectively oxidized by Mn/Yb/Er/CeO_(2) to produce the oxidized TMB(ox TMB),showing a significant absorption signal at 652 nm.Additionally,nitrite can react with ox TMB to produce yellow diazotized ox TMB,which is accompanied by an elevated absorption signal at 445 nm and a decreased absorption signal at 652 nm.Thus,based on the oxidase-mimetic activity of Mn/Yb/Er/CeO_(2) and the diazotization reaction between NO_(2)^(-)and ox TMB,a ratiometric colorimetric assay was established for NO_(2)^(-)detection in food.Furthermore,by integrating Mn/Yb/Er/CeO_(2) with a smartphone,a colorimetric smartphone-sensing platform was successfully fabricated for visualization and quantitative detection of NO_(2)^(-).Notably,this two-detection mode showed excellent sensitivity,selectivity,reliability and practicability in monitoring the NO_(2)^(-)in real samples,impling its great potential for food safety.
基金Supported by the National Natural Science Foundation of China,No.82372172the Key Research and Development Plan Project of Heilongjiang Province,No.GA23C007+3 种基金the Heilongjiang Province Postdoctoral Start-up Fund,No.LBH-Q20037the Research Project of Heilongjiang Provincial Health Commission,No.20231717010461the Special Fund for Clinical Research of Wu Jie-ping Medical Foundation,No.320.6750.2022-02-16the Scientific Research Innovation Fund of the First Affiliated Hospital of Harbin Medical University,No.2021M08.
文摘BACKGROUND The common cause of sodium nitrite poisoning has shifted from previous accidental intoxication by exposure or ingestion of contaminated water and food to recent alarming intentional intoxication as an employed method of suicide/exit.The subsequent formation of methemoglobin(MetHb)restricts oxygen transport and utilization in the body,resulting in functional hypoxia at the tissue level.In clinical practice,a mismatch of cyanotic appearance and oxygen partial pressure usually contributes to the identification of methemoglobinemia.Prompt recognition of characteristic mismatch and accurate diagnosis of sodium nitrite poisoning are prerequisites for the implementation of standardized systemic interventions.CASE SUMMARY A pregnant woman was admitted to the Department of Critical Care Medicine at the First Affiliated Hospital of Harbin Medical University due to consciousness disorders and drowsiness 2 h before admission.Subsequently,she developed vomiting and cyanotic skin.The woman underwent orotracheal intubation,invasive mechanical ventilation(IMV),and correction of internal environment disturbance in the ICU.Her premature infant was born with a higher-than-normal MetHb level of 3.3%,and received detoxification with methylene blue and vitamin C,supplemental vitamin K1,an infusion of fresh frozen plasma,as well as respiratory support via orotracheal intubation and IMV.On day 3 after admission,the puerpera regained consciousness,evacuated the IMV,and resumed enteral nutrition.She was then transferred to the maternity ward 24 h later.On day 7 after admission,the woman recovered and was discharged without any sequelae.CONCLUSION MetHb can cross through the placental barrier.Level of MetHb both reflects severity of the sodium nitrite poisoning and serves as feedback on therapeutic effectiveness.
文摘This study aimed to evaluate the quality of water from village boreholes by measuring physicochemical parameters such as nitrates, nitrites, and total organic carbon (TOC). Forty-five (45) village pumps from the Southern (Basse Côte) and the Northern (Korhogo) region of Cte d’Ivoire (west Africa) were sampled. Physicochemical parameters such as temperature, pH, conductivity at 25˚C, and turbidity were determined in situ, while nitrite and nitrate were analyzed according to ISO 10304-1 (2007) standard and total organic carbon (TOC) by NF EN 1484 (1997) standard. The results showed that the borehole waters of the Basse Côte and Korhogo analyzed are acidic, with an average temperature of 27.51˚C ± 0.16˚C and 29.95˚C ± 0.51˚C respectively for the Basse Côte and Korhogo regions. The borehole waters of the Basse Côtedo not contain nitrites, while those of Korhogo have average nitrite contents of 0.32 mg/l. The average nitrate rate in the waters of the Basse Côte and Korhogo are 12.08 ± 2.11 mg/l and 11.03 ± 3.18 mg/l respectively. The average TOC concentration of the waters of the Basse Côte is 1.28 ± 0.32 mg/l and that of Korhogo is 0.56 ± 0.09 mg/L. The study showed that the borehole waters of the Basse Côte and Korhogo have average temperatures between 27.4˚C and 29.95˚C with a slightly acidic pH value and acceptable salinity. The TOC concentrations obtained at the different sampling points were all below the French standard (2 mg/L) except for certains pumps of the Basse Côte. The water samples from the Basse Côte were devoid of nitrite. On the other hand, those from Korhogo revealed the presence of nitrite. Also, the borehole waters of the regions of the Basse Côte and Korhogo contain relatively high nitrate contents, presumably due to anthropometric activity. Overall, our study on the quality of drinking water showed that the waters analyzed are in compliance with international standards and safe for consumption.
文摘Food safety problems caused by excessive nitrite addition have been frequently reported and the detection of nitrite in food is particularly important. The standing time during the pretreatment of primary sample has a great influence on the concentration of nitrite tested by spectrophotometric method. In this context, three kinds of food samples are prepared, including canned mustard, canned fish and home-made pickled water. A series of standing times are placed during the sample pretreatments and the corresponding nitrite contents in these samples are detected by spectrophotometric method based on N-ethylenediamine dihydrochloride. This study aims to find out a reasonable standing time during the pretreatment of food sample, providing influence factor for precise detection of nitrite.
基金The Hi_Tech Research and Development Program(863) of China(2004AA601020) the National Natural Science Foundation of China(No.50478047)andthe Open Grant of Beijing Key Laboratory
文摘The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments applying the sequencing batch reactor（SBR） activated sludge process to domestic wastewater with low C/N ratio. The addition of sodium chloride（NaCI） to influent was established to achieve nitrite build-up. The high nitrite accumulation, depending on the salinity in influent and the application duration of salt, was obtained in SBRs treating saline wastewater. The maintenance results indicated that the real-time SBRs can maintain stable nitrite accumulation, but conversion from shorter nitrification-denitrification to full nitrification-denitrification was observed after some operation cycles in the other SBR with fixed-time control. The presented method is valuable to offer a solution to realize and to maintain nitrogen removal via nitrite under normal conditions.
基金Supported by the National Natural Science Foundation of China (21076090)
文摘Two artificial intelligence techniques, artificial neural network and genetic algorithm, were applied to optimize the fermentation medium for improving the nitrite oxidization rate of nitrite oxidizing bacteria. Experiments were conducted with the composition of medium components obtained by genetic algorithm, and the experimental data were used to build a BP (back propagation) neural network model. The concentrations of six medium components were used as input vectors, and the nitrite oxidization rate was used as output vector of the model. The BP neural network model was used as the objective function of genetic algorithm to find the optimum medium composition for the maximum nitrite oxidization rate. The maximum nitrite oxidization rate was 0.952 g 2 NO-2-N·(g MLSS)-1·d-1 , obtained at the genetic algorithm optimized concentration of medium components (g·L-1 ): NaCl 0.58, MgSO 4 ·7H 2 O 0.14, FeSO 4 ·7H 2 O 0.141, KH 2 PO 4 0.8485, NaNO 2 2.52, and NaHCO 3 3.613. Validation experiments suggest that the experimental results are consistent with the best result predicted by the model. A scale-up experiment shows that the nitrite degraded completely after 34 h when cultured in the optimum medium, which is 10 h less than that cultured in the initial medium.
文摘The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end product was studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibited and very high levels of nitrite accumulation at different salinities were achieved under the conditions of 25—28℃, pH 7.5? ?.0 , and the influent ammonia nitrogen of 40—70 mg/L when seawater flow used to flush toilet was less than 35%(salinity 12393 mg/L, Cl - 6778 mg/L) of total domestic wastewater flow, which is mainly ascribed to much high chlorine concentration of seawater. Results showed that high seawater salinity is available for short-range nitrification to nitrite as the end product. When the seawater flow used to flush toilet accounting for above 70% of the total domestic wastewater flow, the removal efficiency of ammonia was still above 80% despite the removal of organics declined obviously(less than 60%). It was found that the effect of seawater salinity on the removal of organics was negative rather than positive one as shown for ammonia removal.
