Impacts of slurry application methods and inhibitors on gaseous emissions and N2O pathways in meadow-cinnamon soil.

This study aimed to evaluate the impact of mitigation practices (slurry application methods and inhibitors applications) on gas emissions and identify the soil N2O production pathways in cattle slurry applied soil using isotopocule mapping approach. First, we compared the NH3 and N2O emissions of cattle slurry applied soil in a summer maize field experiment in north China plain (NCP) with four treatments: control (CK, no fertilization), slurry application using surface (SA-S), slurry application using band application (BA-S), and chemical fertilizer application using band application (BA-C). Then, an incubation experiment was conducted to investigate the mitigation effect of nitrification inhibitors (dicyandiamide, DCD) and denitrification inhibitors (procyanidins, PC) and their combination (DCD + PC) on gaseous N emissions with slurry applied using incorporation (IA) or surface application (SA) methods. The results showed that the total gaseous N emissions (N2O-N and NH3-N) in field were in the order of SA-S (1534 mg m-2) > BA-S (338 mg m-2) > BA-C (128 mg m-2) > CK (55 mg m-2), and the dominant N loss contributor varied from NH3 in SA-S (∼89%) to N2O in BA-S (∼94%) and BA-C (∼88%). Moreover, the isotopocule mapping approach indicated that emitted N2O of the slurry applied soil in field appeared to have lower rN2O values and led to more N2O + N2 emissions at the initial fertilization period. The incubation experiment indicated that the N2O emissions of slurry-applied soil were significantly reduced by DCD (∼45%) and DCD + PC (∼67%) application in comparison with CK (p < 0.05), and the stronger contributions of bacterial denitrification/nitrifier denitrification to N2O production were revealed by the lower δ15NSP in N2O using the isotopocule mapping approach. In conclusion, in NCP the gaseous losses of the slurry applied field can be largely reduced by using incorporation method, and greater reduction could be achieved given the simultaneous application of nitrification/denitrification inhibitors.

Dicyandiamide-assisted HKUST-1 derived Cu/N-doped porous carbon nanoarchitecture for electrochemical detection of acetaminophen.

MOFs-derived metal/carbon materials have been considered as promising candidates for the electrochemical detection of micropollutants. However, the aggregation of metal nanoparticles and structure collapse of precursor MOFs during pyrolysis significantly hamper the improvement on detecting performance. Herein, a dicyandiamide-assisted strategy is utilized to synthesize well-dispersed Cu/N-doped porous carbon nanoarchitecture (CuNC) for the electrochemical detection of acetaminophen (AP). The constructed CuNC sensor exhibits excellent electro-analytical performance for monitoring AP with linear range from 0.01 µM to 921.2 µM, and the low detection limit of 2.46 nM (S/N = 3). The improved performance of CuNC sensor is ascribed to the introduction of dicyandiamide, which can prevent HKUST-1 framework breakage and reduce the aggregation tendency of Cu, leading to the evenly distributed small Cu nanoparticles, abundant N species, hierarchical channel structure, and high conductivity carbon framework. These advantages endow predominant repeatability, stability, and selectivity of CuNC sensor. This strategy provided a novel approach to preparing MOFs-derived carbon nanoarchitectures with excellent electroanalysis performance to monitor micropollutants.

Dispersive liquid-liquid extraction based on magnetic Pickering emulsion followed by gas chromatography-tandem mass spectrometry for the simultaneous determination of aldehydes in environmental water samples.

A dispersive liquid-liquid extraction based on Pickering emulsion stabilized with ferroferric oxide grafted nitrogen-doped graphitized carbon black has been developed to simultaneously determine seven aldehydes in environmental water samples, in combination with pentafluorobenzyl hydroxylamine precolumn derivatization gas chromatography-tandem mass spectrometry. The nitrogen-doped graphitized carbon was prepared from dicyandiamide waste residue with a simple acid wash process. The effects of magnetic emulsifier amount, extraction time, solution pH, and oil/water volume ratio on the formation of magnetically responsive Pickering emulsion and the extraction efficiency of the proposed dispersive liquid-liquid extraction were also investigated. Under the optimized conditions, satisfactory linearities were obtained for all aldehydes with correlation coefficients larger than 0.9984. The limits of detection and quantitation of seven aldehydes were in the range of 17.3-30.1 ng/L and 54.3-103.4 ng/L, respectively, with intra- and interday relative standard deviations less than 8.6%. The mean recoveries at three spiked levels ranged from 70.0 to 101.4%. With the Pickering emulsion as a "minimized extractor", the extraction was accomplished within 5 min. After extraction, the magnetic disperser could be recovered for reuse at least five times by an external magnetic field. The proposed method was demonstrated to be feasible, simple, and economic for the trace analysis of the aldehydes in environmental water samples.

Simultaneous quantification of N-butylthiophosphoric triamide and dicyandiamide in urea formulation by liquid chromatography with tandem mass spectrometry.

A new liquid chromatography with tandem mass spectrometry method employing a mixed-mode zwitterionic stationary phase was developed for simultaneous determination of urease inhibitor (N-butylthiophosphoric triamide) and nitrification inhibitor (dicyandiamide) in urea fertilizer. Molecular modeling based on density functional theory calculations was employed to provide an insight into the interaction mechanism of urea, dicyandiamide, and N-butylthiophosphoric triamide with zwitterionic stationary phase in chromatographic separation system. The detection of analytes was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode using positive electrospray ionization. The ion transitions monitored were m/z 85→68 for dicyandiamide and m/z 168.2→74 for N-butylthiophosphoric triamide, respectively. The standard calibration curves of dicyandiamide and N-butylthiophosphoric triamide were linear over the range of 1.0 ̶ 15 ppm (coefficient of determination = 0.9984), 0.05 ̶ 1 ppm (coefficient of determination = 0.9995), with limit of detection of 25 and 5 ppb, respectively. The recoveries of low, middle, and high concentrations were from 96.7 to 105.8% for N-butylthiophosphoric triamide and 94.4 to 105.8% for dicyandiamide with accuracy (relative error %) of ≤5.8% and ≤5.8%, the precision (coefficients of variation) was ≤2.0% and ≤2.9%, respectively. The validated method was successfully applied on real urea samples to determine N-butylthiophosphoric triamide and dicyandiamide simultaneously.

Systemic granulomatous disease in dairy cattle during a dicyandiamide feeding trial.

CASE HISTORY: Mature, in-calf, non-lactating, Friesian or Friesian-cross cows were fed dicyandiamide (DCD) at daily doses of 0.15 g/kg (Group 1; n=31), 0.45 g/kg (Group 2; n=21) and 0.75 g/kg (Group 3; n=12), as part of a safety trial, which also included a control group (n=15). Daily health observations were carried out on each cow until Day 86 of the study. On Day 28 one cow from Group 3 was observed with signs of disease, and subsequently disease was noted in other cows. CLINICAL FINDINGS: Clinical signs in the first case included depression, pyrexia (40.9°C), salivation and dehydration, in addition to progressive weight loss, followed by death on Day 32. Other cows from all treatment groups developed clinical signs of disease resulting in euthanasia of seven animals. Disease occurred in 10/12 (83%) cows in Group 3, 11/21 (52%) cows in Group 2, and 7/31 (23%) cows in Group 1. Clinical signs were variable and included dermatitis and pruritus of the head and neck, petechial haemorrhages, pyrexia, weight loss, thrombocytopenia, neutropenia, and regenerative anaemia. PATHOLOGICAL FINDINGS: Gross findings included generalised lymphadenopathy, subcutaneous oedema, petechiation of mucosal and serosal surfaces, and gastrointestinal haemorrhage. Histologically, multiple organs and tissues contained inflammatory foci characterised by infiltrates of lymphocytes, plasma cells, macrophages and occasionally prominent multinucleated giant cells and eosinophils. DIAGNOSIS: Multisystemic granulomatous and haemorrhagic syndrome resembling cell-mediated hypersensitivity, associated with DCD ingestion. CLINICAL RELEVANCE: This is the first report of toxicity in cattle associated with ingestion of DCD. The proportion of affected cows increased with increasing dose of DCD, but not all cattle in the high dose group developed disease, therefore additional factors may determine whether or not an individual cow will develop DCD-associated disease.

Non-destructive detection of dicyandiamide in infant formula powder using multi-spectral imaging coupled with chemometrics.

BACKGROUND: Dicyandiamide (DCD) contamination of milk and milk products has become an urgent and broadly recognised topic as a result of several food safety scares. This study investigated the potential of using multi-spectral imaging (405-970 nm) coupled with chemometrics for detection of DCD in infant formula powder. Partial least squares (PLS), least squares-support vector machines (LS-SVM), and back-propagation neural network (BPNN) were applied to develop quantitative models. RESULTS: Compared with PLS and LS-SVM, BPNN considerably improved the prediction performance with coefficient of determination in prediction (RP2) = 0.935 and 0.873, residual predictive deviation (RPD) = 3.777 and 3.060 for brand 1 and brand 2 of infant formula powders, respectively. Besides, multi-spectral imaging was able to differentiate unadulterated infant formula powder from samples containing 0.01% DCD with no misclassification using BPNN model. CONCLUSION: The study demonstrated that multi-spectral imaging combined with chemometrics enables rapid and non-destructive detection of DCD in infant formula powder. © 2016 Society of Chemical Industry.

Effect of the application of cattle urine with or without the nitrification inhibitor DCD, and dung on greenhouse gas emissions from a UK grassland soil.

Emissions of nitrous oxide (N2O) from soils from grazed grasslands have large uncertainty due to the great spatial variability of excreta deposition, resulting in heterogeneous distribution of nutrients. The contribution of urine to the labile N pool, much larger than that from dung, is likely to be a major source of emissions so efforts to determine N2O emission factors (EFs) from urine and dung deposition are required to improve the inventory of greenhouse gases from agriculture. We investigated the effect of the application of cattle urine and dung at different times of the grazing season on N2O emissions from a grassland clay loam soil. Methane emissions were also quantified. We assessed the effect of a nitrification inhibitor, dicyandiamide (DCD), on N2O emissions from urine application and also included an artificial urine treatment. There were significant differences in N2O EFs between treatments in the spring (largest from urine and lowest from dung) but not in the summer and autumn applications. We also found that there was a significant effect of season (largest in spring) but not of treatment on the N2O EFs. The resulting EF values were 2.96, 0.56 and 0.11% of applied N for urine for spring, summer and autumn applications, respectively. The N2O EF values for dung were 0.14, 0.39 and 0.10% for spring, summer and autumn applications, respectively. The inhibitor was effective in reducing N2O emissions for the spring application only. Methane emissions were larger from the dung application but there were no significant differences between treatments across season of application.

Study on Dicyandiamide-Imprinted Polymers with Computer-Aided Design.

With the aid of theoretical calculations, a series of molecularly imprinted polymers (MIPs) were designed and prepared for the recognition of dicyandiamide (DCD) via precipitation polymerization using acetonitrile as the solvent at 333 K. On the basis of the long-range correction method of M062X/6-31G(d,p), we simulated the bonding sites, bonding situations, binding energies, imprinted molar ratios, and the mechanisms of interaction between DCD and the functional monomers. Among acrylamide (AM), N,N'-methylenebisacrylamide (MBA), itaconic acid (IA), and methacrylic acid (MAA), MAA was confirmed as the best functional monomer, because the strongest interaction (the maximum number of hydrogen bonds and the lowest binding energy) occurs between DCD and MAA, when the optimal molar ratios for DCD to the functional monomers were used, respectively. Additionally, pentaerythritol triacrylate (PETA) was confirmed to be the best cross-linker among divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDMA), trimethylolpropane trimethylacrylate (TRIM), and PETA. This is due to the facts that the weakest interaction (the highest binding energy) occurs between PETA and DCD, and the strongest interaction (the lowest binding energy) occurs between PETA and MAA. Depending on the results of theoretical calculations, a series of MIPs were prepared. Among them, the ones prepared using DCD, MAA, and PETA as the template, the functional monomer, and the cross-linker, respectively, exhibited the highest adsorption capacity for DCD. The apparent maximum absorption quantity of DCD on the MIP was 17.45 mg/g.

Impact of dicyandiamide on emissions of nitrous oxide, nitric oxide and ammonia from agricultural field in the North China Plain.

Nitrous oxide (N2O), nitric oxide (NO) and ammonia (NH3) emissions from an agricultural field in the North China Plain were compared for three treatments during a whole maize growing period from 26 June to 11 October, 2012. Compared with the control treatment (without fertilization, designated as CK), remarkable pulse emissions of N2O, NO and NH3 were observed from the normal fertilization treatment (designated as NP) just after fertilization, whereas only N2O and NH3 pulse emissions were evident from the nitrification inhibitor treatment (designated as ND). The reduction proportions of N2O and NO emissions from the ND treatment compared to those from the NP treatment during the whole maize growing period were 31% and 100%, respectively. A measurable increase of NH3 emission from the ND treatment was found with a cumulative NH3 emission of 3.8 ± 1.2 kg N/ha, which was 1.4 times greater than that from the NP treatment (2.7 ± 0.7 kg N/ha).

Analysis of trace dicyandiamide in stream water using solid phase extraction and liquid chromatography UV spectrometry.

An improved method for trace level quantification of dicyandiamide in stream water has been developed. This method includes sample pretreatment using solid phase extraction. The extraction procedure (including loading, washing, and eluting) used a flow rate of 1.0mL/min, and dicyandiamide was eluted with 20mL of a methanol/acetonitrile mixture (V/V=2:3), followed by pre-concentration using nitrogen evaporation and analysis with high performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV). Sample extraction was carried out using a Waters Sep-Pak AC-2 Cartridge (with activated carbon). Separation was achieved on a ZIC(®)-Hydrophilic Interaction Liquid Chromatography (ZIC-HILIC) (50mm×2.1mm, 3.5µm) chromatography column and quantification was accomplished based on UV absorbance. A reliable linear relationship was obtained for the calibration curve using standard solutions (R(2)>0.999). Recoveries for dicyandiamide ranged from 84.6% to 96.8%, and the relative standard deviations (RSDs, n=3) were below 6.1% with a detection limit of 5.0ng/mL for stream water samples.

Core Soil Microorganisms and Abiotic Properties as Key Mechanisms of Complementary Nanoscale Zerovalent Iron and Nitrification Inhibitors in Decreasing Paclobutrazol Residues and Nitrous Oxide Emissions.

Agrochemical residues and nitrous oxide (N2O) emissions have caused considerable threats to agricultural soil ecology. Nanoscale zerovalent iron (nZVI) and nitrification inhibitors might be complementary to each other to diminish soil agrochemical residues and N2O emissions and enhance soil bacterial community diversities. Compared to the control, the nZVI application declined soil paclobutrazol residues by 5.9% but also decreased the bacterial community co-occurrence network node. Combined nZVI and Dicyandiamide applications significantly decreased soil N2O emission rates and paclobutrazol residues but promoted Shannon diversity of the bacterial community. The increased soil pH, ammonium nitrogen, and Actinobacteriota could promote soil paclobutrazol dissipation. The nZVI generated double-edged sword effects of positively decreasing paclobutrazol residues and N2O emissions but negatively influencing soil multifunctionalities. The nZVI and Dicyandiamide could be complementary to each other in diminishing soil agrochemical residues and N2O emission rates but promoting soil bacterial community diversities simultaneously.

Microwave-assisted extraction and determination of dicyandiamide residue in infant formula samples by liquid chromatography-tandem mass spectrometry.

A simple, precise, accurate, and validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of dicyandiamide residue in infant formula samples. Following microwave-assisted extraction with 5% formic acid and clean-up on a Sep-Pak AC-2 SPE cartridge, samples were separated on a ZIC-HILIC HPLC column (150 × 2.1mm i.d., 5-µm film thickness; Merck KGaA, Darmstadt, Germany) with 20mM ammonium acetate solution-acetonitrile as mobile phase at a flow rate of 0.25 mL/min. A linear calibration curve was obtained in the concentration range from 1.0 to 50 ng/mL. Infant formula samples were fortified with dicyandiamide at 3 levels, producing average recovery yields of 83.6 to 95.7%. The limits of detection and quantification of dicyandiamide were 3 and 10 µg/kg, respectively. Due to its simplicity and accuracy, the straightforward method is particularly suitable for routine dicyandiamide detection.

Combined effects of spent mushroom substrate and dicyandiamide on carbendazim dissipation in soils: Double-edged sword effects and potential risk controls.

Repeated and high-dose carbendazim applications have caused serious soil carbendazim contamination, and eco-friendly and economical approaches have been suggested to promote carbendazim removal in agricultural soil. Spent mushroom substrate (SMS) is a special recycled resource after harvesting mushrooms and can be utilized in contaminated soil amendment. The SMS application into agricultural soil might increase antibiotic resistance gene abundances, and the health risks of SMS application might be reduced with reasonable management to adjust the related electron transport of soil nitrification or denitrification. In this study, the SMS and nitrification inhibitor dicyandiamide were used to remediate agricultural soil contaminated with the carbendazim, and the carbendazim contents, soil microbial biomass, activities and community and human disease genes were determined. Compared to the control treatment, the combined applications of SMS and dicyandiamide significantly decreased soil carbendazim content by 38.14% but significantly enhanced soil ß-glucosidase, chitinase, arylsulfatase, urease and electron transfer system activities. The relative abundances of Proteobacteria and Actinobacteria were increased by 11.0% and 8.2% with the SMS application, respectively. The carbendazim residues were negatively correlated with the soil pH, electron transfer system activities and relative abundances of Proteobacteria and Actinobacteria. The relative abundances of human disease genes were also dramatically increased with the SMS application, but compared to the SMS alone, extra dicyandiamide application significantly reduced the relative abundances of human disease genes in soils. The SMS applications into fungicide-contaminated soils could generate double-edged sword effects of facilitating fungicide dissipation but leading to potential health risk increase, while applying the dicyandiamide with SMS might be an effective strategy to decrease the negative effect of health risk.

Detection of nitrification inhibitor dicyandiamide: A direct electrochemical approach.

A single run approach for rapid detection of nitrification inhibitor, dicyandiamide (DCD) using electrogenerated chlorine assisted polymerization through azo bond, under acidic conditions and at a preanodized screen printed carbon electrode (SPCE*) is presented. The role of chloride containing support electrolyte in acidic medium along with oxygen functionalities/edge sites are found to be crucial for the successful oxidative polymerization and subsequent adsorption of oxidized products on the electrode surface. The SEM, cyclic voltammetry and X-ray photoelectron spectroscopy studies were used to characterize the polymer film formation. The system exhibited a linear range between 20 and 170 µM with a detection limit of 3 µM (S/N = 3). The method was successfully tested for the detection of DCD in dairy and water samples. Simultaneous detection of DCD in the presence of melamine has also been demonstrated.

Linking Carbendazim Accumulation with Soil and Endophytic Microbial Community Diversities, Compositions, Functions, and Assemblies: Effects of Urea-hydrogen Peroxide and Nitrification Inhibitors.

Fungicide carbendazim accumulation in soils and plants is a wide concern. Nitrogen (N) is a substantial nutrient limiting crop growth and affecting soil microbial activity and the community in degrading fungicides. We investigated the effects of urea-hydrogen peroxide (UHP) and nitrification inhibitors Dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) on carbendazim accumulation and soil and endophytic microbial communities. The UHP application had negligible influences on soil and plant carbendazim accumulation, but the combined UHP and DCD decreased soil carbendazim accumulation by 5.31% and the combined UHP and DMPP decreased plant carbendazim accumulation by 44.36%. The combined UHP and nitrification inhibitor significantly decreased the ratios of soil Firmicutes and endophytic Ascomycota. Soil microbial community assembly was governed by the stochastic process, while the stochastic and deterministic processes governed the endophyte. Our findings could provide considerable methods to reduce fungicide accumulation in soil-plant systems with agricultural N management strategies.

Measurement of grass uptake of the urease inhibitor NBPT and of the nitrification inhibitor dicyandiamide co-applied with granular urea.

Grass uptake and phytoaccumulation factors of N-(n-butyl) thiophosphoric triamide (NBPT) and dicyandiamide (DCD) were quantified. Following the application of urea fertilizer treated with the inhibitors in Irish grassland, grass samples were collected at 5, 10, 15, 20, and 30 day time intervals following five application cycles. Uptake of NBPT by grass was below the limit of quantitation of the analytical method (0.010 mg NBPT kg-1). Dicyandiamide concentrations in grass ranged from 0.004 to 28 mg kg-1 with the highest concentrations measured on days 5 and 10. A reducing trend in concentration was found after day 15. The DCD phytoaccumulation factor was ranged from 0.004% to 1.1% showing that DCD can be taken up by grass at low levels when co-applied with granular urea. In contrast, NBPT was not detected indicating that grass uptake is unlikely when co-applied with granular urea fertilizer. The contrasting results are likely due to very different longevity of DCD and NBPT along with the much lower rate of NBPT, which is used compared with DCD.

Effects of dicyandiamide, phosphogypsum and superphosphate on greenhouse gas emissions during pig manure composting.

This study investigated the effects of dicyandiamide, phosphogypsum and superphosphate on greenhouse gas emissions and compost maturity during pig manure composting. The results indicated that the addition of dicyandiamide and phosphorus additives had no negative effect on organic matter degradation, and could improve the compost maturity. Adding dicyandiamide alone reduced the emissions of ammonia (NH3), methane (CH4) and nitrous oxide (N2O) by 9.37 %, 9.60 % and 31.79 %, respectively, which was attributed that dicyandiamide effectively inhibited nitrification to reduce the formation of N2O. Dicyandiamide combined with phosphogypsum or superphosphate could enhance mitigation of the total greenhouse gas (29.55 %-37.46 %) and NH3 emission (18.28 %-21.48 %), which was mainly due to lower pH value and phosphoric acid composition. The combination of dicyandiamide and phosphogypsum exhibited the most pronounced emission reduction effect, simultaneously decreasing the NH3, CH4 and N2O emissions by 18.28 %, 38.58 % and 36.14 %, respectively. The temperature and C/N content of the compost were significantly positively correlated with greenhouse gas emissions.

[Field-amplified sample injection and graphene quantum dot dual preconcentration in the analysis of melamine and dicyandiamide by capillary electrophoresis].

Sulfur-doped graphene quantum dots (S-GQDs) were prepared by the pyrolysis of citric acid and mercaptopropionic acid. Compared with graphene quantum dots (GQDs), the S-GQDs have improved surface state and chemical reactivity, and thus, exhibited stronger interaction with cations. Based on its excellent affinity for cations, a dual preconcentration technique combining field-amplified sample injection (FASI) and S-GQDs as multianalyte carriers was developed for the determination of melamine and dicyandiamide by capillary electrophoresis (CE). During the FASI process, a large quantity of analytes was introduced into the capillary and accumulated at the capillary inlet. Concurrently, the S-GQDs migrated to the anode and captured the analytes on its surface at the boundary of the sample and buffer solution. The use of S-GQDs allows the capture of abundant analytes, which can amplify the detection signal. This new protocol was evaluated by the quantitative determination of melamine and dicyandiamide in metformin hydrochloride preparations. The effect of volume fraction of the S-GQDs in the buffer solution, the composition and pH of the buffer, and the sample injection time on the preconcentration and separation were investigated. By controlling the pH at 4.6, the sample injection time was prolonged to 450 s. A very large amount of melamine and dicyandiamide, bearing positive electric charges, were injected into the capillary and were captured by S-GQDs. The assay using FASI preconcentration and S-GQDs as enhancer resulted in a 1.6×105-fold improved sensitivity compared with that obtained with traditional 10-kV electrokinetic injection for 10 s. The calibration curves of melamine and dicyandiamide were obtained in the concentration range from 1.0×10-14 to 1.0×10-8mol/L, with correlation coefficients (r2) >0.999. The detection limits (S/N=3) were 2.6×10-15mol/L for melamine and 5.7×10-15mol/L for dicyandiamide. The recoveries of the two analytes were 95.9%-102.4% and 92.0%-106.0%, respectively, with relative standard deviations (RSDs) of no more than 5%. The RSD values of peak height, peak area, and migration time were all less than 5.6%. This method is reliable, easy, and exhibits a good separation effect. This proves that the S-GQD-enhanced CE method could be developed into a new and sensitive technique for the determination of melamine and dicyandiamide in different preparations of metformin hydrochloride.

Nitrogen-Doped Hierarchical Porous Activated Carbon Derived from Paddy for High-Performance Supercapacitors.

A facile and environmentally friendly fabrication is proposed to prepare nitrogen-doped hierarchical porous activated carbon via normal-pressure popping, one-pot activation and nitrogen-doping process. The method adopts paddy as carbon precursor, KHCO3 and dicyandiamide as the safe activating agent and nitrogen dopant. The as-prepared activated carbon presents a large specific surface area of 3025 m2·g-1 resulting from the synergistic effect of KHCO3 and dicyandiamide. As an electrode material, it shows a maximum specific capacitance of 417 F·g-1 at a current density of 1 A·g-1 and very good rate performance. Furthermore, the assembled symmetric supercapacitor presents a large specific capacitance of 314.6 F·g-1 and a high energy density of 15.7 Wh·Kg-1 at 1 A·g-1, maintaining 14.4 Wh·Kg-1 even at 20 A·g-1 with the energy density retention of 91.7%. This research demonstrates that nitrogen-doped hierarchical porous activated carbon derived from paddy has a significant potential for developing a high-performance renewable supercapacitor and provides a new route for economical and large-scale production in supercapacitor application.

Measuring Responses of Dicyandiamide-, 3,4-Dimethylpyrazole Phosphate-, and Allylthiourea-Induced Nitrification Inhibition to Soil Abiotic and Biotic Factors.

Nitrification inhibitors (NIs) such as dicyandiamide (DCD), 3,4-dimethylpyrazole phosphate (DMPP), and allylthiourea (AT) are commonly used to suppress ammonia oxidization at different time scales varying from a few hours to several months. Although the responses of NIs to edaphic and temperature conditions have been studied, the influence of the aforementioned factors on their inhibitory effect remains unknown. In this study, laboratory-scale experiments were conducted to assess the short-term (24 h) influence of eight abiotic and biotic factors on the inhibitory effects of DCD, DMPP, and AT across six cropped and non-cropped soils at two temperature conditions with three covariates of soil texture. Simultaneously, the dominant contributions of ammonia-oxidizing archaea (AOA) and bacteria (AOB) to potential ammonia oxidization (PAO) were distinguished using the specific inhibitor 2 phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO). Our results revealed that AT demonstrated a considerably greater inhibitory effect (up to 94.9% for an application rate of 75 mg of NI/kg of dry soil) than DCD and DMPP. The inhibitory effect of AT was considerably affected by the relative proportions of silt, sand, and clay in the soil and total PAO. In contrast to previous studies, the inhibitory effects of all three NIs remained largely unaffected by the landcover type and temperature conditions for the incubation period of 24 h. Furthermore, the efficacy of all three tested NIs was not affected by the differential contributions of AOA and AOB to PAO. Collectively, our results suggested a limited influence of temperature on the inhibitory effects of all three NIs but a moderate dependence of AT on the soil texture and PAO. Our findings can enhance the estimation of the inhibitory effect in soil, and pure cultures targeting the AOA and AOB supported ammonia oxidization and, hence, nitrogen dynamics under NI applications.